That strange and mysterious phenomenon in the life of birds, their migratory journeys, repeated at fixed

intervals, and with unerring exactness, has for thousands of years

called forth the astonishment and admiration of mankind.

(H. Gätke 1895.)

Stopover site ecology

of Montagu´s Harrier (Circus pygargus)

in East-Morocco

Almut Schlaich

@ Rob Buiter

Carl von Ossietzky Universität Oldenburg Master of Science in Biology

MASTER´S THESIS

Stopover site ecology of Montagu´s Harrier ( Circus pygargus) in

East-Morocco Submitted by: Almut E. Schlaich Conducted at: Institute of Avian Research „Vogelwarte Helgoland“, Wilhelmshaven

and Dutch Montagu´s Harrier Foundation, The Netherlands 1st Examiner: Dr. Klaus-Michael Exo 2nd Examiner: Prof. Dr. Franz Bairlein Supervisors: Dr. Christiane Trierweiler, Ben J. Koks Oldenburg, 28 March 2011

1

Table of Contents

1. Introduction ............................................................................................................... 3

1.1 Bird migration ....................................................................................................... 3

1.2 Stopovers during bird migrations .......................................................................... 4

1.3 Study species: Montagu´s Harrier (Circus pygargus) ........................................... 6

1.4 Study area: stopover site East-Morocco ............................................................. 11

1.5 Research goals .................................................................................................. 12

2. Materials and Methods ............................................................................................ 13

2.1 Satellite telemetry data ...................................................................................... 13

2.2 Location of the study area East-Morocco ........................................................... 14

2.3 Habitat characteristics of the study area East-Morocco ...................................... 15

2.4 Loose observations and localization of roosts .................................................... 17

2.5 Road transect counts ......................................................................................... 17

2.6 Habitat selection ................................................................................................ 18

2.7 Prey transect counts .......................................................................................... 19

2.8 Pellet analysis .................................................................................................... 23

2.9 Spatial and statistical analyses .......................................................................... 25

3. Results .................................................................................................................... 26

3.1 Montagu´s Harriers´ stopover sites in East-Morocco and their use as revealed

by satellite telemetry ................................................................................................ 26

3.2 Distribution and abundance of Montagu´s Harriers in East-Morocco: field data .. 35

3.3 Habitat selection during stopover ....................................................................... 40

2

3.4 Prey abundance and prey choice ....................................................................... 47

4. Discussion ............................................................................................................... 57

5. Summary ................................................................................................................. 64

6. Zusammenfassung .................................................................................................. 66

7. Samenvatting .......................................................................................................... 68

8. Acknowledgements ................................................................................................. 71

9. Literature ................................................................................................................. 72

10. Appendix ............................................................................................................... 77

3

1. Introduction

1.1 Bird migration

An estimated 50 billion birds worldwide migrate twice a year between their breeding

and non-breeding grounds (Berthold 1993). The phenomenon of seasonal use of

different areas, often on two continents, is the result of changing food availability at

higher latitudes. Whereas food is abundant on the breeding grounds in summer,

seasonal environments suffer from scarcity in winter. By migrating to areas closer to

the equator, often on the other hemisphere, birds avoid periods with low food

supplies in their breeding range. In the Palaearctic-Afrotropical migration system,

millions of birds are travelling every year between their breeding grounds in Europe

and the wintering areas in Africa, often south of the Sahara (Newton 2008; Zwarts et

al. 2009).

Migration to and from places visited in subsequent years by the same

individual bird requires great navigational skills. Birds covering thousands of

kilometers on their migratory routes use compass information as well as landscape

characteristics and other environmental cues for orientation (Alerstam 1990; Able

2001). Migration patterns are partly under genetic control, allowing juveniles to

perform the journey on their own, controlling the timing of migration and leading the

birds on the right routes (Helbig 1996). Nevertheless, migration systems can be

modified even within relatively short time intervals, as shown e.g. by migration

patterns in Blackcaps (Sylvia atricapilla) changing within 30 years to wintering in

Britain instead of the Mediterranean (Berthold & Querner 1995).

There are different strategies in birds to cover large distances. Birds can

either migrate as fast as possible to minimize the time spent on migration (‘time

minimization model’), which requires large fuel stores, or save energy due to lower

fat load if they have the possibility to stop and feed at multiple places on the route

(‘energy minimization model’; Alerstam & Lindström 1990). Observed strategies are

mostly a mixture of these models, depending on the species considered, on

conditions that vary e.g. between years, or on individual performance.

Migration is one of the most important stages of the yearly life cycle of

migratory birds, involving many hazards. Beside the direct costs of migratory flight,

journeying through various, often unknown landscapes can lead to additional costs.

Weather conditions, confrontation with diseases, competition and predation pressure

4

en route and at wintering sites can have effects on individuals and their survival and

eventually on population dynamics.

Most raptor species are soaring birds, making use of thermals to gain height

and of gliding flight to cover inter-thermal distances (Alerstam 1990; Newton 2008).

Since the effectiveness of soaring flight is related to wing surface, species with

narrower and tipped wings use more flapping flight than species with broader wings.

Soaring flight requires the least energy of all forms of flight, hence some migratory

raptor species accept much longer routes than the direct connection between

breeding and wintering areas, avoiding barriers like open water (Newton 2008).

1.2 Stopovers during bird migrations

Regardless of the migration strategy followed by a species or an individual, often the

whole distance cannot be covered in a single flight. Birds may have to stop during

migration to refuel their energy stores. This is especially the case before and after

crossing large ecological barriers like deserts and oceans.

A recent review on the terminology of stopover vs. staging (Warnock 2010)

concluded that the term stopover relates to sites used for several days and by few

individuals of a population at any one time, whereas staging sites are used by

thousands of individuals for a longer period (for details see Table 1 in Warnock

2010). In this thesis, I investigate the stopover site ecology of the study species,

Montagu´s Harrier (Circus pygargus), in an area in East-Morocco that is used during

several days and not in high numbers at the same time (see results). Therefore, the

term stopover is used throughout the text.

Conditions at stopover sites can have an impact on migration speeds,

reproduction and survival rates of individual migrants through food availability,

competition, predation and disturbance, sometimes also affecting population size

(Newton 2008). Timing and success of migration may be strongly influenced by food

supply at stopover sites, where birds have to refuel in limited time (Newton 2008).

Food availability at stopover sites can influence the condition of individuals, which in

turn determines the frequency and duration of stopovers, and finally migration speed.

Interference and depletion competition might limit weight gain rates of birds at

stopover sites. Competitive interactions with conspecifics and inter-specific

competition can lead to differences in refueling rates, stopover duration and survival,

5

especially in species holding short-time territories (Newton 2008). Nevertheless, the

quality of a stopover site is not only influenced by food availability and competition,

but also by predation risk and other hazards (Newton 2008). For instance,

disturbances and parasites may influence the migratory performance of individual

birds by weakening the organism and lowering food intake rates (Newton 2008). Also

other factors like illegal persecution may play a role. All the factors mentioned above

can have impacts on the survival of an individual and on performance and success

during following breeding seasons, so called carry-over effects.

Kerlinger (2009) stated that “long-term survival of many species is linked to success

during migration, and thus to the preservation of stopover sites”. One factor that

potentially limits populations of migrants is the availability of stopover sites (Newton

2008). This holds especially true for waders, which have to stop over at adequate

coastal sites that are often far from each other. In contrast, land bird species may

have the possibility to stop over at various sites on their route, which also reduces

competition. Conditions at stopover sites and during migration may also have effects

on the population level due to additional mortality, as well as on the individual

through carry-over effects (Newton 2008; Bauchinger et al. 2009). This was shown

for White Storks (Ciconia ciconia) and Barn Swallows (Hirundo rustica), where

population changes correlated with conditions during stopover (Robinson et al. 2003;

Schaub et al. 2005). It was shown for several bird species that body condition at

migration sites corresponds to re-sighting rates and thus survival (Newton 2008,

Table 27.1), indicating the importance of favorable ecological conditions at stopover

sites.

Although a lot of information is available on migrations and stopovers in birds, most

studies refer to songbird species. Raptors differ in their migration ecology in many

points, because they are mostly heavier, often use soaring flight and, as predators,

depend on adequate prey. However, they face similar challenges and limitations at

stopover sites as other taxonomic groups of birds.

For many raptor species not much is known about the precise routes they

travel or the sites they use for stopover. At some migration bottlenecks, e.g.

Gibraltar, where amazing numbers of raptors pass by at the same time, regular

migration counts are carried out (Bensusan et al. 2007). In more remote places

6

however, little is known about the whereabouts of these birds. Recently, new insights

were gained by satellite tracking of larger raptor species. This revealed for example

that most of the satellite-tagged Swedish Ospreys (Pandion haliaetus) made one

longer stopover of 3-4 weeks on autumn migration (Hake et al. 2001). Ospreys spent

more time on migration in autumn than in spring due to more stopover days

(Alerstam et al. 2006). Nevertheless, Ospreys seemed to minimize time spent on

autumn migration to arrive early at wintering sites for gaining a good territory (Kjellen

et al. 1997). This is possible because Ospreys are fly-and-forage migrants

(Strandberg & Alerstam 2007), which have the possibility to feed on the go.

However, the specialization in feeding only on fish limits appropriate stopover sites.

Ospreys therefore often continue migration when flying above non-optimal habitats,

because stopping over in e.g. arid areas brings no benefits (Thorup et al. 2006).

Another species employing the fly-and-forage strategy is the Marsh Harrier

(Circus aeruginosus; Klaassen et al. 2010). In a study on 17 satellite-tagged

Swedish Marsh Harriers, low migration speeds indicated stopover behavior on

autumn migration throughout Europe, but only one individual made a stopover in N-

Africa (Klaassen et al. 2010). During spring migration, however, the Marsh Harriers

made some stopovers at the northwestern coast of Africa and in Europe (Klaassen

et al. 2010).

A third example of raptor stopover behavior is shown by Bald Eagles

(Haliaeetus leucocephalus). These North American eagles are partial migrants, with

birds from populations breeding in Saskatchewan, Alberta, and the Northwest

Territories of Canada using traditional stopover sites on their migration southward

along the Rocky Mountains, where they feed on carcasses of salmon for several

weeks (Bildstein 2006).

1.3 Study species: Montagu´s Harrier ( Circus pygargus)

Of 193 bird species migrating from the West Palaearctic to sub-Saharan Africa, 24

are raptors (Newton 2008). Harriers (Circus) are raptors showing some distinct life

history traits and characteristic behaviors (Simmons 2000). All species share

morphological characteristics such as slender wings and long tails resulting in their

buoyant flight and exceptionally low wing loading (Simmons 2000). Some species of

the genus Circus are regularly polygynous, and it is possibly for this reason that

sexes are markedly dimorphic in plumage. The fact that all species are ground

breeders contributes to the separation of the genus from other raptors, as well as

their enormous acoustical abilities.

pass’ in the air between pairs of harriers.

Hen Harrier (Circus cyaneus

(C. macrourus; Simmons 2000).

or residential, the harrier species are

Montagu´s Harriers are sexually dimorphic (Fig. 1.1) with females weighing

about 345 g and males about 265 g (Table 2.2 in

distribution, their breeding range is centered in Europe, extending northward towards

Scandinavia and south to the Mediterranean and the coast of northwest Africa

(Clarke 1996). The breeding range also covers parts of Asi

Kazakhstan and the upper Yenisey

Fig. 1.1: Montagu´s Harrier (

Dutch Montagu´s Harrier Foundation.

Montagu´s Harriers are not endangered gl

countries as decreasing or endangered

sexes are markedly dimorphic in plumage. The fact that all species are ground

breeders contributes to the separation of the genus from other raptors, as well as

their enormous acoustical abilities. A special and spectacular behavior is the ‘food

pass’ in the air between pairs of harriers. Four species of harriers breed

Circus cyaneus), Marsh Harrier, Montagu´s Harrier, and Pallid Harrier

; Simmons 2000). Except for Hen Harriers, which are partial migrants

or residential, the harrier species are migrants wintering south of the Sahara.

Montagu´s Harriers are sexually dimorphic (Fig. 1.1) with females weighing

about 345 g and males about 265 g (Table 2.2 in Simmons 2000). With a Palaearctic

distribution, their breeding range is centered in Europe, extending northward towards

Scandinavia and south to the Mediterranean and the coast of northwest Africa

The breeding range also covers parts of Asia, extending eastwards to

Kazakhstan and the upper Yenisey (Del Hoyo et al. 1992).

Fig. 1.1: Montagu´s Harrier (Circus pygargus). A, C: Adult male, B, D: Adult female. Photos:

Dutch Montagu´s Harrier Foundation.

Montagu´s Harriers are not endangered globally but red-listed in some European

countries as decreasing or endangered (Burfield & Van Bommel 2004; Sudfeldt

7

sexes are markedly dimorphic in plumage. The fact that all species are ground-

breeders contributes to the separation of the genus from other raptors, as well as

A special and spectacular behavior is the ‘food-

cies of harriers breed in Europe:

), Marsh Harrier, Montagu´s Harrier, and Pallid Harrier

Except for Hen Harriers, which are partial migrants

migrants wintering south of the Sahara.

Montagu´s Harriers are sexually dimorphic (Fig. 1.1) with females weighing

Simmons 2000). With a Palaearctic

distribution, their breeding range is centered in Europe, extending northward towards

Scandinavia and south to the Mediterranean and the coast of northwest Africa

a, extending eastwards to

). A, C: Adult male, B, D: Adult female. Photos:

listed in some European

(Burfield & Van Bommel 2004; Sudfeldt et al.

8

2008; Trierweiler & Koks 2009). Over half of the world population of Montagu´s

Harriers breeds in Europe (Arroyo et al. 2004; Burfield & Van Bommel 2004), but

substantial population declines have been observed in many well monitored

breeding areas (Zijlstra & Hustings 1992; Millon et al. 2004; Illner 2007; Trierweiler &

Koks 2009). With about 400 breeding pairs, Germany has the biggest Montagu´s

Harrier breeding population in NW-Europe (Mebs & Schmidt 2006).

Natural breeding habitats as moor and heath lands decreased in availability

for breeding. Therefore, at the end of the last century, Montagu´s Harriers started to

breed in agricultural land e.g. wheat, barley and alfalfa fields (Arroyo et al. 2004;

Koks et al. 2007). Habitat loss due to intensification of agricultural land use and

human persecution are the main causes of population declines of Montagu´s

Harriers since the 1940s (Clarke 1996). However, conditions in the wintering areas

may also have contributed to the observed population decrease (Thiollay 2006;

Zwarts et al. 2009).

Today, ground-breeding birds of agricultural landscapes face several threats

due to agricultural activities (Sudfeldt et al. 2008). Clutches, nestlings and incubating

females are in danger to be killed by mowing or harvesting. The population in The

Netherlands nearly went extinct in 1987. Therefore, conservation issues such as

nest protection and habitat improvements have been employed since the 1990s.

Thanks to a large scale set aside of farmland in 1988, the population started

increasing again (Koks et al. 2007). This positive trend continued due to intensive

conservation efforts of the Dutch Montagu´s Harrier Foundation and led to a

successful increase of the breeding pairs with about 50 pairs breeding in 2010

(Dutch Montagu´s Harrier Foundation, pers. comm.).

Montagu´s Harrier breeding biology

By the end of April, Montagu´s Harriers start arriving in their breeding areas in

northwestern Europe. In the first phase, pair formation takes place induced by

courtship behavior of males, e.g. courtship feedings and spectacular flight

maneuvers called ‘skydancing’. Pairs defend only small territories around their

nesting site during the breeding season. Nests are built on the ground by the female

and contain mostly 3-4 eggs. After 28-29 days of incubation by the female, the

nestlings hatch. During this time and when the chicks are young, the male provides

food for the female and the young. In the second half of the nestling phase, the

9

female may start hunting again and may help feeding the nestlings. The nestling

period is normally 31-33 days, after fledging the young are still fed for several weeks.

Because females start incubating the clutch after laying the first egg, nestlings differ

in age and size (Clarke 1996). In autumn, females tend to leave the breeding area

about a week earlier than males and fledglings (Clarke 1996).

Montagu´s Harriers´ migrations

Because Montagu´s Harriers are long-distance migrants, they spend only four to five

months of the year in their breeding areas (see Fig. 1.2 in Trierweiler 2010). The

larger part of their life cycle is spent on migration and at wintering sites. Keeping in

mind that population dynamics are significantly influenced by ecological conditions

during migration and at wintering sites, including investigations of the whole life cycle

of a bird is of great importance (1) to deepen biological understanding and (2) to

maximize effects of conservation strategies (Bairlein 2003).

Ringing birds and analyzing ring recoveries is the oldest way of studying

migration and, along with providing large sample sizes, for many small species the

only possibility to gain insight in migration routes, stopover areas and wintering

grounds (Bairlein 2001). Up to 2008, only 47 ring recoveries of Montagu´s Harriers

were reported from Africa, thereof 15 south of the Sahara (see Fig. 180 in Trierweiler

& Koks 2009) illustrating roughly the wintering areas but not showing migration

routes.

Telemetry methods involving devices like radio tags, satellite transmitters or

GPS loggers deliver more extensive data than ringing, which do not depend on the

distribution of birdwatchers and different ring recovery probabilities. Furthermore,

these techniques deliver not one data point per bird like ringing, but up to several

thousand per individual. This also allows for studies on individual birds over years,

resulting in information on life cycle and lifetime reproductive success. Telemetry

also offers the opportunity to locate stopover sites precisely, whereas direct

observation methods can only use minimum values between first and last sighting

(Newton 2008). Nevertheless, the use of telemetry techniques is limited to species

large and heavy enough to carry the necessary transmitters or loggers.

Recently, the assumption of northwest European Montagu´s Harriers making

a loop migration via Gibraltar in autumn and returning via Italy in spring (García &

Arroyo 1998) was disproved by using telemetry data. In 2005, light enough satellite

10

transmitters were available to fit Montagu´s Harriers for the first time. Trierweiler et

al. (2007b) described for the first time the exact migration routes of Montagu´s

Harriers from the Netherlands to West Africa. They showed that about ¾ of the NW-

European population take a western route via France and Spain to winter in

Senegal, Mauretania and Mali and ¼ of the birds takes a central route via Italy to

Niger and Nigeria on spring as well as on autumn migration (Trierweiler 2010). The

satellite telemetry data revealed that for west European breeding birds the route via

Spain is of greatest overall importance (Trierweiler et al. 2007b; Exo et al. 2010;

Trierweiler 2010). On migration, Montagu´s Harriers encounter diverse hazards: they

have to cover ca. five thousand kilometers, stand sometimes unpredictable weather

conditions, cross barriers, and may be victims of illegal persecution, e.g. on Malta

(Raine 2007).

Montagu´s Harriers wintering ecology

Montagu´s Harriers from eastern breeding populations winter in India and eastern,

up to southern Africa, whereas birds from European populations migrate to the Sahel

in West Africa (Trierweiler & Koks 2009). Satellite telemetry revealed that individuals

use several traditional winter home ranges, which they revisit in consecutive years

(Trierweiler 2010). Investigations of the wintering sites in West Africa have been

conducted since 2006 by the Dutch Montagu´s Harrier Foundation (Trierweiler et al.

2006; Trierweiler et al. 2007a). In the wintering areas, Montagu´s Harriers feed

mainly on resident grasshoppers and therefore follow the green vegetation south

during winter. This was named the ‘green belt hypothesis’ (Trierweiler & Koks 2009;

Trierweiler 2010). Raptor counts in the Sahel showed an alarming decline in raptor

numbers between 1969 -73 and the beginning of the 21st century (Thiollay 2006).

Threats causing declines in resident as well as wintering raptor species are habitat

loss due to desertification and degradation, shortage of carcasses, poisoning for

predator control or persecution for trade of meat and body parts (Thiollay 2006). One

satellite tracked Montagu´s Harrier was trapped by a farmer, who believed that the

harriers endangered his chicken (Trierweiler et al. 2007b; Trierweiler & Exo 2009).

Summarizing, the Montagu´s Harrier is an appropriate study species to gain deeper

insight in the stopover ecology of raptors, because it is a long-distance migrant

wintering south of the Sahara, it is classified as threatened in some European

11

breeding areas where it is already the object of conservation practice, and it can be

fitted with satellite transmitters.

1.4 Study area: stopover site East-Morocco

Beside the detailed insights about migration routes and wintering areas mentioned

above (see 1.3., Montagu’s Harriers´ migrations and wintering ecology), satellite

tracking data yielded information on stopover sites and stopover behavior of

northwestern European individuals. Half way (ca. 2500 km) between Europe and

West Africa, the stopover area in East-Morocco is the only stopover site outside

breeding and wintering grounds (Trierweiler & Exo 2009). Other areas which are

used by Montagu´s Harriers during stopover lay in the breeding areas in Germany,

France and Spain. This can also be interpreted as prospecting (Trierweiler & Exo

2009).

During spring as well as autumn migration, noticeable concentrations of

tracked Montagu´s Harriers were found in East-Morocco and West-Algeria

(Trierweiler & Exo 2009; Trierweiler 2010; Fig. 3.2). The high plateaus of East-

Morocco were previously not known to lie on the migration route of Montagu´s

Harriers or to be an important stopover area (Clarke 1996; García & Arroyo 1998).

Thevenot et al. (2003) reported no observations of the species in this part of

Morocco, most probably due to a lack of observers. Regarding its position, the area

may be suitable for harriers that prepare themselves for the crossing of the Sahara

desert in autumn, as has been shown for trans-Sahara migrating passerines (e.g.

Bairlein 1991). An alternative function of the area may be awaiting favorable weather

conditions for the desert crossing. Supporting the latter is the observation that

Montagu´s Harriers on autumn migration returned to the stopover area after trying to

cross the Sahara and started again some days later (Trierweiler 2010), which has

also been shown for passerines (Deutschlander & Muheim 2009).

In spring, the area may act as refueling site after the crossing of the desert

and before the crossing of the Mediterranean, the migration through Europe and the

oncoming breeding season. This means that carry-over effects of ecological

conditions at this stopover site could influence the breeding success.

12

Knowing not only which areas are valuable to preserve but also why they are

important is required to give management and conservation advice. To study the

ecological function and importance of the stopover site in East-Morocco for

Montagu´s Harriers, expeditions to this site were conducted during the spring and

autumn migration periods in 2010. This is the first time that stopover ecology of a

raptor species is specifically investigated on-site. In this thesis, results from these

field data will be combined with results from satellite tracking data of Montagu’s

Harriers to investigate Montagu’s Harrier stopover ecology in Northwest-Africa.

1.5 Research goals

To understand stopover ecology of migrating birds, three processes must be

examined: habitat selection, stopover duration, and weight change (Kerlinger 2009).

The first two aspects are studied for Montagu´s Harriers in this thesis.

The following questions were to be answered by doing fieldwork (FW) in East-

Morocco and combining the results with analyses of satellite telemetry data (STD):

• Position and importance of stopover areas in Northwest-Africa (FW, STD).

• How long do Montagu´s Harriers stay in Northwest-Africa during stopover

during spring and autumn migration (STD)?

• Are they site faithful to the stopover area in Northwest-Africa (STD)?

• What is the spatial distribution of Montagu´s Harrier in East-Morocco (FW,

STD)?

• Which habitats are used by Montagu´s Harriers in East-Morocco (FW, STD)?

• What are the main food sources of Montagu´s Harriers in East-Morocco

(FW)?

• What is the spatial distribution of potential Montagu´s Harrier prey species in

East-Morocco (FW)?

• Are there differences between spring and autumn stopovers?

• Which hazards may Montagu´s Harriers encounter in East-Morocco (FW)?

• What do the present findings imply with respect to conservation strategies?

13

2. Materials and Methods

2.1 Satellite telemetry data

Since 2005 Montagu´s Harriers have been fitted with 9.5 g or 12 g solar satellite

transmitters (PTT-100, Microwave Telemetry Inc., Columbia, MD, USA) in an

international collaboration project (Trierweiler 2010). Data for analyses in this thesis

were obtained from 20 individuals using the western flyway via Spain (Appendix 1).

The data contained 50 migration tracks from 20 birds crossing Morocco between

2006 and 2010. Transmitters were programmed to either a 10:48 h on:off cycle or a

6:16 h cycle (Trierweiler et al. 2007b). The transmitters were attached using teflon-

ribbon backpacks and their weight did not exceed 5 % of total body mass of harriers

(Trierweiler et al. 2007b). Data were obtained from the Argos system via CLS

(Collecte Localisation Satellites, Toulouse, France).

For the present analyses, only fixes lying in Morocco (area see 2.2) were

selected. Bias can arise because of multiple fixes of one transmitter per day, or due

to regional differences in the frequency of satellite contact. To avoid this bias, per

individual only the best fix per day, indicated by Argos Location Class (LC; CLS

2008), was included in the analyses (Trierweiler & Klaassen in prep.). The fixes lying

in Morocco were categorized as stopover or travel days using the distance between

fixes on consecutive days as criterion. The threshold to distinguish between stopover

and travel fixes was set to a distance of 50 km between consecutive days

(Trierweiler & Klaassen in prep.; Trierweiler 2010). The resulting dataset was

checked graphically for outliers and consistency by plotting all location fixes in a

geographical information system (GIS).

The average sample size per stopover in Morocco was 6.62 ± 3.12 (SD) daily

fixes per bird for spring (n = 13 tracks) and 6.42 ± 3.73 daily fixes per bird for autumn

(n = 12). Therefore, calculation of individual home ranges - requiring a minimum of

20 fixes (Trierweiler in prep.; Trierweiler 2010) - was not possible. Instead, kernel

densities over stopover fixes of all individuals were calculated for spring and autumn,

respectively, revealing stopover areas used by multiple birds. From the kernel

volume contours the approximate size of the stopover areas was calculated. The

timing and duration of stopovers was analyzed considering the first stopover fix in

Morocco as arrival date and the last stopover fix as departure date. Site fidelity of

individual Montagu´s Harriers was determined visually.

14

2.2 Location of the study area East-Morocco

Fieldwork was conducted during spring (9 - 22 April) and autumn migration (9 - 21

September) 2010 in East-Morocco (Fig. 2.1). In the following, the term ‘Morocco’ is

used to denote the Kingdom of Morocco including the southern provinces that form

the Western Sahara (Fig. 2.1B), an area of 884,905 km² in total. Our study area (Fig.

2.1C) was approximately 46,657 km² in spring and 80,510 km² in autumn. The area

covered was situated mainly between Oujda (34°40´N, 1°55´W) in the north and

Bouarfa (32°31´N, 1°57´W) in the south. In Septembe r 2010, we also proceeded in a

southwestern direction up to Errachidia (34°55´N, 4 °26´W).

The high plateaus of East-Morocco have an elevation between 1100 and 1400 m

above sea level and are dominated by steppe vegetation (Fig. 2.1D, for details see

2.3). This rather remote area of Morocco is, apart from few villages and towns,

inhabited by farmers and herdsmen living in tents and solitary farms.

Fig. 2.1: Study area East-Morocco. A: position of Morocco (yellow) in northwestern Africa. B:

position of covered area (shaded in red) in Morocco. C: detailed view of study area East-

Morocco (shaded in black). D: Halfa steppe, a typical landscape of the high plateaus of the

Moroccan East. Source: ESRI basemaps: World Physical Map (A, B), World Street Map (C).

15

2.3 Habitat characteristics of the study area East- Morocco

North Morocco has mainly a Mediterranean climate with hot and dry summers and

winter rains (Thevenot et al. 2003). Annual rain-fall is approximately 300 mm in the

east (Thevenot et al. 2003). Climax steppe vegetation is covering East-Morocco

(Thevenot et al. 2003; García et al. 2008). The high plateaus are sparsely covered

by this steppe dominated by Halfa grass (Stipa tennacissima) which grows in

tussocks reaching heights of up to ca. 1.5 m (here referred to as Halfa steppe). We

also visited areas where the steppe vegetation was dominated by Artemisia spp.,

hereafter called Artemisia steppe (see García et al. 2008). Artemisia plants are

obviously avoided by grazing livestock due to their content of repellent chemicals

(pers. comm. of a local forester). Other parts of steppe were dominated by Fredolia

aretioides, Anabasis articulata, Hammada scoparia, Noaea mucronata or were

covered by mixed vegetation. The steppes of East-Morocco were in some parts

interspersed with small patches of farmland. These were mainly cereal fields in the

eastern steppe regions and some pastures in the region close to Oujda (for regions

see 2.7, Fig. 2.3). On cereal fields, stems were sparse, mixed with other vegetation

and containing open spots.

Due to intensive grazing by sheep and goats, great parts of the area were

degraded, suffering first from shortened vegetation and in later stages from erosion.

To counteract erosion, the government of Morocco (through Eaux et Forêts)

manages the soil structure and plants shrubs (e.g. Atriplex spec.) in some restricted

areas. We categorized these areas as ‘anti-erosion’ areas during transect counts.

To record habitat characteristics quantitatively, we noted the percentage surface

area covered by grass/herbs, crop, stones and sand, the number of trees/ha and the

number of shrubs/ha. This was done during road transect counts (see 2.5, Fig. 2.2)

to gain reference data on habitat types. During prey transect counts (see 2.7, Fig.

2.3), additionally the height of grass/herbs and crop was estimated.

16

The following habitat types were classified during transect counts:

• F – farmland (cereal fields in spring, plowed fields in autumn)

• V – villages and towns

• AE- anti-erosion (plantation of shrubs e.g. Atriplex spec., trees e.g. eucalyptus

or conifers, or working the soil for reducing erosion)

• N – natural steppe with different vegetation communities e.g. Fredolia

aretioides, Anabasis articulata

• NH – natural steppe dominated by Halfa grass Stipa tennacissima

• NA – natural steppe dominated by Artemisia spec.

• T – trees (coniferous woods in mountainous regions e.g. Juniperus spec.)

• R – rocks (stony hillsides or desert)

• S – sand

• O – oasis (only categorized as such during the autumn expedition)

• W – wadi (along or in a wadi)

• D – depression (depressed area with green vegetation, often salt tolerant

plants or farmland; called ‘ex-lac’, because they are flooded irregularly)

• Combinations of two of the habitat types in transition zones.

Whenever we noted habitat type and other habitat characteristics, we also

determined the degree of degradation according to the following broad categories:

• 0 – intact landscape, no signs of overgrazing or erosion

• 1 – little degradation, signs of overgrazing and erosion

• 2 – much degradation, strong overgrazing and erosion

• 3 – total degradation, bare soil due to overgrazing, strong erosion.

17

2.4 Loose observations and localization of roosts

All observations of Montagu´s Harriers and other raptor species, also outside

transect counts, were noted during the trips with exact geographical position and

habitat information. If possible sex and age of Montagu´s Harries were determined

and noted. Only observations where sex and age could be determined exactly were

used for sex ratio calculations and age classes.

The roost encountered in spring close to Ain Benimathar could be located by

tracking a satellite tagged Montagu´s Harrier sleeping at this roost close to real time.

An additional roost of two individuals was found northeast of Ain Benimathar on the

high plateau, also using satellite tracking information. In autumn, we observed a

roost containing about six Montagu´s and 15 Marsh Harriers located south of

Taourirt. The roost observed in autumn was found during systematic (road transect)

scans of large areas of East-Morocco. To show the distribution and abundance of

migrating Montagu´s Harriers throughout Morocco, I plotted all our observations in a

map (see 3.2, Fig. 3.5). Additionally, I plotted all observations mentioned with clear

location descriptions in Thevenot et al. (2003) in the same map.

2.5 Road transect counts

For estimating distribution and abundance, all raptor species were counted along

roads and paths while driving with a maximum speed of 80 km/h (Thiollay 2006;

Trierweiler et al. 2007a). The mean speed was considerably lower due to the quality

of roads. Additionally, the habitat type and the degradation state of the landscape

were noted every 5 km as described above (see 2.3). Habitat characteristics were

also noted when a raptor was spotted, together with noting the exact geographic

position by making a GPS waypoint. We drove 2043 and 2250 km of road transects

in spring and autumn, respectively (Fig. 2.2). We also estimated the distance of

observed birds to the road at the point they were first seen. For our standardized

forms see Appendix 2.

18

Fig. 2.2: Road transects in East-Morocco covered in spring and autumn 2010, respectively,

and Montagu´s Harriers observed during road transect counts (red symbols). Size of symbols

refers to number of harriers observed at a location. Source: ESRI basemap: World Street

Map.

2.6 Habitat selection

Satellite telemetry data and Globcover digital land cover map

To estimate habitat availability in stopover areas in comparison to a larger reference

area, a digital global land cover map was used. Globcover (Globcover Source Data:

© ESA / ESA Globcover Project, led by MEDIAS-France/Postel) is a global land

cover map with a spatial resolution of 300 m. It contains 22 global land cover classes

which are defined within the UN Land Cover Classification System (LCCS).

Globcover was derived from classification of a time series of satellite images

covering the period December 2004 - June 2006 and has an accuracy level of 67.10

% (Bicheron et al. 2008).

The digital map was intersected with home range contours from stopover

sites instead of with individual location fixes to minimize bias due to location fix

errors (Trierweiler 2010, Box D). First, Morocco was used as reference area

19

(excluding the Western Sahara or southern provinces, but including a part of Algeria

to cover the whole stopover area; see blue polygon Fig. 3.10). To test on a smaller

scale if the habitat composition at the stopover sites differs from that of a reference

area, the home range contours were intersected with two smaller reference areas:

one in western Morocco and one in eastern Morocco (see black polygons Fig. 3.10).

To estimate the goodness of inferences on habitat availability and use, ground

truthing was conducted. Therefore the habitat types noted at 1316 prey transect start

and end points from our spring and autumn trips were compared to Globcover raster

cell values.

Own observations and reference habitat classifications: Field data

To analyze habitat selection of Montagu´s Harriers during stopover in East-Morocco,

I used all observations of individuals during road and prey transect counts (see 2.7),

at roosts and loose observations. The habitats used by Montagu´s Harriers were

compared to the total amount of available habitat of each category obtained through

reference habitat classifications noted every 5 km during road transect counts. The

analysis was conducted over six habitat types for which enough references were

available (contributing >4 % to available habitat of all road transect references,

except for Artemisia steppe in autumn with only 1.8 %). The separate calculation for

roosting individuals contained only four habitat types (farmland, natural steppe,

Artemisia steppe, Halfa steppe) due to the small sample size.

2.7 Prey transect counts

To estimate the abundance of potential prey for Montagu´s Harriers in the stopover

area and in different habitat types, we conducted standard prey transect counts by

foot (Trierweiler 2006; Trierweiler et al. 2007a). This method was used in the

wintering areas by Altenburg & Wymega during transect counts in Mali, Senegal and

Guinea Bissau (Trierweiler et al. 2007a; Zwarts et al. 2009) and by now is used by B.

Arroyo in India and by V. Bretagnolle in Senegal. While walking through a

homogenous area of one habitat type, all birds 30 m left and right of the transect line

were recorded and, if possible, determined to species level. All mammals, reptiles

and amphibians were also noted in that transect. Two meters to both sides of the

imaginary transect line, all large insects (locusts < 3 cm, 3-7 cm, > 7 cm; beetles < 1

20

cm, 1-2 cm, > 2 cm) and active holes of mammals (Ø ≤ 3 cm, Ø = 4-10 cm, Ø > 10

cm) and reptile holes (only in autumn) were noted. Reptile holes could be

distinguished by their flat, squared appearance. Birds passing by over the transect

were noted separately. All songbirds and birds smaller in size than doves were

categorized as potential prey for Montagu´s Harriers, thereby excluding e.g. raptor-,

wader-, and shrike species. For each prey transect, GPS waypoints were taken at

the beginning and end of the line. Furthermore, information on the habitat type of the

transect was collected (see 2.3 for details). For our standardized forms see Appendix

3.

During the two excursions in 2010, we counted 658 prey transects with a total

length of 294.85 km (Fig. 2.3). In spring, 267 prey transects were counted with a total

length of 120.56 km. The average length was 0.45 km ± 0.28 (min: 0.06 km, max:

1.77 km). In autumn 2010, 391 prey transects were counted with a total length of

174.29 km. The average length was 0.45 ± 0.31 km (min: 0.04 km, max: 2.6 km). To

look for regional differences in prey abundance, I divided the study area in 11

regions, based on the dominant vegetation and landscape types in these areas (Fig.

2.3).

The Shannon-Weaver diversity index is a concept of diversity, i.e. of the distribution

of observations among categories (Zar 1996):

�´ = − � �� ln ���

� �

Where k is the number of species and pi is the proportion of individuals found in

species i.

Here it is used to calculate the distribution of individual potential prey birds among

species. If the individuals are evenly distributed over the species the diversity is high,

if nearly all individuals belong to the same species it is low. Normally values lie

between 1.5 and 3.5. The Shannon-Weaver diversity index was calculated for

potential prey bird species in spring and autumn to compare seasons and for the 11

regions to find spatial differences.

21

Since not only the distribution of individuals among species influences H’ but also the

number of species, the evenness was also calculated (Zar 1996):

�´ = �´ln (�)

The evenness expresses the observed diversity as a proportion of the maximum

possible diversity and may be referred to as homogeneity or relative diversity (Zar

1996). It takes a value between 0 and 1, with higher values indicating a more even

distribution of individuals among species.

The dominance structure of potential prey species is the relative abundance of a

species in comparison to other species (Townsend et al. 2002):

��������� = �� ∗ 100�

Where ni is the number of individuals of species i and N the total number of

individuals. A species is considered subrezedent if the dominance <1 %, rezedent if

it is 1 - 2 %, subdominant if it is 2 - 5 % or dominant if it is 5 - 10 %.

Shannon-Weaver diversity index, evenness and dominance were calculated

considering only individuals determined to species level inside transects, i.e. birds

flying over the transect were left out.

22

Fig. 2.3: Position of prey transects (dots) in East-Morocco in spring and autumn 2010

distributed over eleven regions (red: region number, black: region name). Regions are

separated according to common landscape characteristics. Source: ESRI basemaps: World

Physical Map.

23

2.8 Pellet analysis

To gain insight in food choice during stopovers, pellets (undigested, regurgitated

prey remains, including bones, fur, feathers, etc.) were collected at roosts. Each

pellet was stored separately in an envelope, dried and stored at room temperature

for 7 months. Each pellet was weighed to the nearest 0.01 g and length and width of

the largest fragment were measured with calipers to the nearest 0.1 mm. The

difference between pellets of Montagu´s and Marsh Harriers is mainly in size, with

Montagu´s Harriers producing smaller pellets. In the field the difference could be

clearly seen from the size of the open spot where the bird was sleeping and the

distance between pellets and droppings at the sleeping place of the bird. The mean

mass of pellets of Montagu´s Harriers (n = 21) was 1.59 g and mean length and

width were 30.9 and 15.6 mm, respectively.

For determination of contents, pellets were dissected and prey items

identified. The determination of prey to species level was not possible, but items

were sorted into higher taxon categories (mammals: hair, bones; reptiles: scales,

bones; birds: eggs, feathers, bones; beetles; plant material). We estimated the

volume percentages of each prey category of a pellet and weighed the different

fractions separately. The number of individuals of each category was determined

using countable fragments: jaws of mammals, bills of birds, heads of beetles (Arroyo

1997; Trierweiler 2010, Box A). If only uncountable remains of prey items were

present, the minimum number of individuals per pellet was set to one.

We multiplied the number of individuals of each category with a fresh (wet) weight

value of an individual for calculating the proportion of biomass each category

contributed to the diet represented in the pellets. Weight values were derived by the

following calculations and considerations.

The pellets contained many egg shell fragments. Because the most abundant

breeding birds were several lark species and we also found several lark nests,

measurements of lark eggs were used for calculations. The weight of lark eggs could

not be determined in the field.

24

Therefore, using the length and width measurements of eggs given in Harrison &

Castell (2004) for 12 lark species (Appendix 4), the weight of eggs was estimated

according to (Hoyt 1979):

� = � ∗ !"#,

where W = weight, Kw = constant, L = length and B = breadth.

Kw is a species-specific weight coefficient that must be determined empirically or

can be derived from literature values of W, L, and B (Hoyt 1979).

� = �$�%/!$�%"$�%²

For this calculation, we used mean values of four lark species from literature: Short-

toed Lark (Calandrella brachydactyla), Lesser Short-toed Lark (Calandrella

rufescens), Crested Lark (Galerida cristata) and Calandra Lark (Melanocorypha

calandra). Mean values for these were: Wlit = 2.9 g, Llit = 21.5 mm, Blit = 16.0 mm

(Glutz von Blotzheim & Bauer 1985).

According to these formulas, the mean weight of a lark egg was estimated as

3.4 g. Since the egg shell accounts for 6 % of the total weight of an egg (BTO Bird

Facts, Shore Lark: http://blx1.bto.org/birdfacts/results/bob9780.htm, 11.11.2010), the

estimated weight of the shell of one egg was considered 0.2 g. This value can also

be found for lark eggs of several individual species (Glutz von Blotzheim & Bauer

1985). Therefore, the number of eggs present in a pellet was estimated by dividing

the total weight of shell fragments by 0.2 g.

For birds, the weight was derived from the mean value of adult birds of four

lark species which were common in the area (see Fig. 3.17; Short-toed Lark, Lesser

Short-toed Lark, Crested Lark and Calandra Lark, mean = 39 g) and nestlings of two

species (Crested and Short-toed Lark, mean over whole nestling period = 11.4 g).

During the spring expedition we observed nestlings and adults with prey regularly.

Making the assumption that half of the prey birds were adults and half nestlings, the

estimated weight of a bird was 25 g.

Estimating the weight of small mammals is constrained, because we could

not confirm during fieldwork which species occur in the study area. The assumed

25

weight of small mammals was set to 23 g, the body mass of a Small Egyptian Gerbil

(Gerbillus gerbillus; http://www.gerbil.info/html/othergerbillus.htm, 03.03.2011).

Since the observed reptiles during prey transects were mainly lizards with a

length of about 7 cm, the weight of reptiles was assumed to be 3.2 g (Meiri 2010).

To define a rough estimate of beetle weights, 1 g, the weight of Calosoma

sycophanta (Coleoptera, Carabidae) from Turkey was used as a representative of

ground beetles (length of freshly emerged adult 2 cm; Kanat & Özbolat 2006).

2.9 Spatial and statistical analyses

All maps in this thesis were produced using ArcMap 9.3 (ESRI 2008) and were

projected in UTM 32N. Encounter probabilities were calculated using the Kernel

density tool of the Spatial Analyst extension in ArcMap. The h-value was estimated

using R 2.12.0 (R Development Core Team 2010).

Stopover durations in spring and autumn and between years were compared using

ANOVA. To test if the sex ratio differed from 1:1 a Chi-square Test was conducted.

Day time dependent variation in raptor observations was tested using ANOVA. The

comparisons of habitat availability in stopover areas and reference areas were

conducted using Chi-square Tests. Habitat preferences of observed Montagu´s

Harriers were calculated using the function compana in R (Callenge 2006). To test

the influence of different parameters on the number of potential prey birds a General

Linear Model (GLM) was calculated. The model contained the parameters season,

time, habitat, degradation, length, observer, the interactions of habitat and

degradation, time and length, season and habitat, and season and degradation. The

best model was fitted by removing first non-significant interactions, then non-

significant parameters. Another GLM with the parameters season, region, and length

was calculated to test for spatial variation in potential prey bird abundance. In both

cases length was kept as variable to correct for the influence of transect length. The

proportions of prey items according to estimated volume and weighed proportions in

pellets were compared using Fisher´s Exact Test. The average proportion based on

number of prey items counted in pellets and estimated biomass of the same

category was also compared using Fisher´s Exact Test.

All statistical tests were conducted in R. All tests were two-tailed. The significance

level was set to α = 0.05.

26

3. Results

3.1 Montagu´s Harriers´ stopover sites in East-Moro cco and their use as

revealed by satellite telemetry

Locations of stopovers

Analyzing satellite data of 20 tagged Montagu´s Harriers crossing Morocco between

2006 and 2010 revealed that there were several important regions for stopover

during spring and autumn migration (Fig. 3.1 and 3.2A). Satellite tracks (shortest

connections between consecutive daily satellite fixes of tracked birds) through

Morocco showed that harriers mainly travel on a northeast-southwest axis through

the country. In East-Morocco, several tracks showed high turning rates, which

indicate the use of the area as a stopover site, because birds stayed several days in

the area. This is confirmed by low travel rates (stopover days, <50 km/day covered)

in this area. On average, half of the harriers stopped over in Morocco while migrating

on a western route via Spain between the European breeding and Sahelian wintering

areas in autumn and spring (Table 1). During autumn migration, 41 % of migrating

individuals used stopover sites in Morocco. During spring migration, Morocco was

even of greater importance with 76 % of tracked Montagu´s Harriers stopping over.

Analyzing stopover fixes in detail revealed two main stopover areas of

Montagu´s Harriers in Morocco. While the western region was only important during

spring migration, East-Morocco showed high encounter probabilities in both seasons

(Fig. 3.2A). The same was true for the year 2010 analyzed separately, when the two

field trips were conducted (Fig. 3.2B). In spring 2010, three satellite tagged

Montagu´s Harriers stopped over in Morocco: Danish adult female Mathilde and

Danish adult male Michael used the western stopover region (length of stay: 14 and

5 days, respectively), whereas Dutch adult male Franz stopped over in East-

Morocco, where we also managed to observe him in the field (length of stay: 12

days). In autumn 2010, Mathilde made a 2-day stop on a plateau (altitude about

1500 m) with agricultural fields about 130 km southeast of Marrakesh and about 10

km west-southwest of Tazenakht. This stop was not in one of the major stopover

areas. Klaus-Dieter in contrast, used the region in East-Morocco, where we

observed him during his 11-day stopover.

27

Table 1: N: Number of satellite tagged northwest European Montagu´s Harriers migrating on a western migration route via Spain in

spring (season S) and autumn (season A). N stopover: number of individuals stopping over in Morocco. % stopover: percentage of all

birds (N) making stopovers in Morocco.

year 2006 2007 2007 2008 2008 2009 2009 2010 2010 2007-2010 2006-2010 all

season A S A S A S A S A S A

N 5 4 8 6 4 3 5 4 7 17 29 46

N stopover 3 3 2 4 2 3 3 3 2 13 12 25

% stopover 60 75 25 67 50 100 60 75 29 76 41 54

27

28

Fig. 3.1: Fifty tracks of 20 satellite tagged northwest European Montagu´s Harriers crossing

Morocco during spring and autumn migration between 2006 and 2010. Lines connect best

fixes per day of each track within Morocco (see methods). Different colors represent different

tracks. Inset map shows close up view of East-Morocco.

29

Fig. 3.2: Satellite fixes of tracked Montagu´s Harriers stopping over in Morocco in spring and

autumn, respectively. Included is only the best fix per day. Green and red points equal fixes. Blue

areas show encounter probabilities >0.00003 as kernel densities. Stopover areas are encircled in

green for spring and in red for autumn. A: Spring 2007 - 2010 (n = 99 fixes, N = 9 birds, n = 14

tracks) and autumn 2006 - 2010 (n = 121, N = 10, n = 13). B: Spring 2010 (n = 29 fixes, N = 3 birds)

and autumn 2010 (n = 13, N = 2).

30

Timing and duration of stopovers

Montagu´s Harriers arrived in Morocco on average on 12 April and departed on 19

April in spring (Table 2). In autumn, they arrived on average on 17 September and

departed on 23 September (Table 2). The duration of 25 stopovers during spring and

autumn migration in Morocco ranged from 2 to 20 days (data: 2006 - 2010, Table 3).

On average it was 9.2 ± 4.56 (SD) days. The stopover duration did not differ

significantly between spring (n = 13) and autumn (n = 12; 9.69 ± 3.71 (SD) days vs.

8.67 ± 5.45 (SD) days, ANOVA, F = 0.011, p = 0.891). The duration of stopovers

was not significantly different between years (2006 - 2010, F = 0.101, p = 0.754).

Examining the timing of individual Montagu´s Harriers stopping over in Morocco in

consecutive years indicated individual differences. Tracked adult male Franz for

example made stopovers in Morocco during spring migration 2007, 2009 and 2010

(Table 3). Twice, he arrived on 6 April and once on 10 April, always before the

average arrival date. On average, he stopped for ca. 11 days. In spring 2008, he

crossed Morocco but did not stop at all. This was also the case for all his 5 autumn

migrations between 2006 and 2010. In contrast, tracked adult female Merel, tagged

in 2006, made stopovers in Morocco on each of her migration trips from autumn

2006 to spring 2009 (Table 3). The duration of her stops varied between 2 and 11

days.

31

Table 2: Mean arrival date and standard deviation (number of days) of arrival and departure dates

of 20 satellite tagged northwest European Montagu´s Harriers´ stopovers in Morocco during spring

and autumn migration, 2006 - 2010 (n = number of individuals).

arrival departure arrival departure

spring mean sd mean sd n autumn mean sd mean sd n

2006 20-Sep 10 28-Sep 19 3

2007 11-Apr 13 18-Apr 8 3 2007 9-Sep 1 19-Sep 1 2

2008 12-Apr 8 21-Apr 5 4 2008 24-Sep 6 3-Oct 15 2

2009 14-Apr 15 16-Apr 3 4 2009 15-Sep 15 18-Sep 14 4

2010 12-Apr 6 21-Apr 4 3 2010 17-Sep 8 22-Sep 1 2

all 12-Apr 10 19-Apr 5 14 all 17-Sep 9 23-Sep 13 13 aSatellite tagged juvenile male Jurek arrived in spring 2009 but stayed the whole summer in East-Morocco. Therefore, the sample size for departure spring 2009 and arrival autumn 2009 was only 3. Because he arrived in spring 2009 and departed in autumn 2009, his dates are included and there the sample size is 4.

Table 3: Arrival and departure date and duration of stopover in days for 13 satellite tagged

northwest European Montagu´s Harriers stopping over in Morocco. No duration of stopover is given

for Jurek, because he stayed the whole summer 2009 in Morocco and Algeria. For details about

individual harriers see Appendix 1.

spring autumn bird arrival departure duration bird arrival departure duration

2007 2006 Franz 6-Apr 14-Apr 9 Freyr 30-Sep 19-Oct 20 Merel 16-Apr 17-Apr 2 Merel 17-Sep 22-Sep 6 Tania 2-Apr 14-Apr 13 Tania 12-Sep 13-Sep 2 2008 2007 Doris 8-Apr 17-Apr 10 Jinthe 10-Sep 20-Sep 11 Edzard 3-Apr 16-Apr 14 Merel 8-Sep 18-Sep 11 Margret 22-Apr 27-Apr 6 2008 Merel 11-Apr 21-Apr 11 Jochen 27-Sep 12-Oct 16 2009 Merel 18-Sep 21-Sep 4 Cathryn 1-Apr 13-Apr 13 2009 Franz 10-Apr 18-Apr 9 Iben 1-Oct 7-Oct 7 Jurek 5-May Jurek 8-Sep 37 Merel 8-Apr 15-Apr 8 Mathilde 2-Sep 7-Sep 6 2010 Remt 11-Sep 18-Sep 8 Franz 6-Apr 17-Apr 12 2010 Mathilde 12-Apr 25-Apr 14 Klaus-Dieter 11-Sep 21-Sep 11 Michael 17-Apr 21-Apr 5 Mathilde 22-Sep 23-Sep 2

32

Size of stopover areas

The size of the stopover area in East-Morocco calculated from kernel density volume

contours of stopover fixes was 21,400 km² (50 % volume contour) and 32,800 km²

(90 % volume contour) in spring and 17,400 km² (50 %) and 26,500 km² (90 %) in

autumn (Fig. 3.3). The area used in the west during spring migration had a size of

36,800 km² (50 %) and 51,400 km² (90 %).

Fig. 3.3: Main stopover areas of 20 satellite tracked Montagu´s Harriers in Morocco (2006 –

2010; see also Fig. 3.2). Red lines indicate 50 % (inner) and 90 % (outer) volume contours of

kernel densities. Because Montagu´s Harriers only use land for stopover, the oceanic part of

the western stopover area was cut off, resulting in an irregular shape of the 90 % kernel

density volume contour. Spring west n = 28 fixes, N = 4 birds, n = 4 tracks; spring east n =

47, N = 5, n = 7; autumn east n = 75, N = 6, n = 8.

33

Site fidelity

Ten satellite tagged Montagu´s Harriers stopped in Morocco both during spring and

autumn migration (2006 – 2010). From three of those birds, data on multiple

stopovers in different years are available (Fig. 3.4).

Dutch adult male Franz stopped over in the eastern spring stopover area in

2007, 2009 and 2010 (Fig. 3.4 left). Within this area, he used a site close to Ain

Benimathar in spring 2009 and 2010. In 2007 and 2010, he also stopped over at a

site on the Maatarka plateau. In spring 2007, he visited additionally the border area

with Algeria east of Tendrara.

Danish adult female Mathilde, on the other hand, did not use the same

stopover site in two subsequent years (Fig. 3.4 centre). She also stopped on the high

plateaus north of Maatarka in autumn 2009. In spring 2010, she stayed several days

in the western spring stopover site around Youssoufia and visited a second site near

Settat. In autumn 2010, she only made a brief stop about 10 km west-southwest of

Tazenakht.

Like Franz, Dutch adult female Merel showed great site fidelity to East-

Morocco (Fig. 3.4 right). In spring 2007, she stayed close to Ain Benimathar. In

spring 2008 as well as autumn 2006 – 2008, Merel used a stopover site west of

Tendrara. In autumn 2006, she additionally visited a site near Boudnib. In autumn

2007, she also made a second stop in western East-Morocco, 120 km north of

Errachidia and 50 km east of Midelt. Only in spring 2009, she stopped somewhere

very different, in the south of Morocco just north of the Sahara desert near Tan-Tan.

34

Fig. 3.4: Stopover areas of three satellite tagged northwest European Montagu´s Harriers stopping over during migration in Morocco.

Shown are daily best satellite fixes during stopover. Stopover areas used by several satellite tagged Montagu´s Harriers (see Fig. 3.3)

are illustrated by 50 % (inner) and 90 % (outer) volume contours of kernel densities. Green lines refer to spring and red lines to

autumn stopover areas. Note the different scales.

34

35

3.2 Distribution and abundance of Montagu´s Harrier s in East-Morocco: field

data

Knowledge of distribution and abundance of Montagu´s Harriers in Morocco has

been scarce and fragmentary with a bias to the west of Morocco (Thevenot et al.

2003; Fig. 3.5). The only scientific expedition which conducted systematic counts

investigating larks in eastern Morocco also observed Montagu´s Harriers regularly

(Jesús T. García, pers. comm.: region around Ain Benimathar 19 individuals in

spring 2010, region around Midelt, north of Errachidia, 7 individuals). During both of

our field trips to Morocco, all Montagu´s Harriers observed during prey or road

transect counts plus all the loose observations outside transects, e.g. at roosts, are

summed to show the abundance of harriers in East-Morocco during spring and

autumn migration, respectively (Fig. 3.6). The high concentration of individuals south

of Ain Benimathar in spring results from a nighttime roost visited several times. At

this roost, approximately 10 Montagu´s and 10 Marsh Harriers slept in an agricultural

field on the ground.

The number of Montagu´s Harriers observed was higher in spring (73) than in

autumn (11). The sex ratio was 0.9 in spring and 1.3 in autumn and not significantly

different from 1.0 (Chi-square Test: spring: p = 0.535; autumn: p = 0.739; Fig. 3.7). In

total, the number of adult birds observed (66 %) was higher than the number of

younger birds (15 %).

36

Fig. 3.5: Observations of breeding and migrating Montagu´s Harriers in Morocco according to

Thevenot et al. 2003 complemented with own observations made during two field trips in

spring and autumn 2010.

Fig. 3.6: Abundance of Montagu´s Harriers in East-Morocco during spring (n = 73) and

autumn (n = 11) 2010, respectively. Included are all individuals seen during road and prey

transect counts and loose observations. Blue areas show encounter probabilities as kernel

densities. Lines stand for the 90 % (outer) and 50 % (inner) volume contours of the kernel

density.

37

B

female male

num

ber

of M

onta

gu´s

Har

riers

0

2

4

6

8

10

adjuvn.a.

A

female male

num

ber

of M

onta

gu´s

Har

riers

0

10

20

30

40

Fig. 3.7: Number of Montagu´s Harriers observed in spring (A, n = 65) and autumn (B, n = 9)

2010, according to sex and age. Included are all loose observations and observations during

road and prey transect counts where the sex of individuals could be exactly determined. n.a.

= age class could not be identified. Note the different scales.

Road transects

In total, we observed 228 raptors during road transect counts (Table 4). The 91

raptors in spring belonged to 11 species, the 137 raptors in autumn belonged to 16

species. Griffon Vultures were only observed in spring, whereas Osprey, Honey

Buzzard, Sparrowhawk, Black-winged Kite and Bonelli´s Eagle were only seen in

autumn. Little Owls were not encountered during road transects in spring, but were

common in autumn. A complete list of all species seen during both trips can be found

in Appendix 5. Montagu´s Harriers were only observed three and six times during

road transect counts in spring and autumn, respectively (see Fig. 2.2).

The overall number of raptors per 100 kilometer road transect was 5.3 (Table 4). Per

100 km transect, 0.1 Montagu´s Harriers were observed in spring and 0.3 in autumn.

The average distance within which counted raptors were located from the

road was 131 ± 162 (SD) m. 92 % of observations lay at a maximum distance of 400

m from the transect line (Fig. 3.8). Raptors could be observed during the whole time

of daylight (Fig. 3.9). The high value from 7:00 – 8:00 h is based on a very few

observation minutes. Otherwise, there was no indication of daytime dependent

variations which could be expected e.g. during the hottest time of the day (ANOVA, F

= 2.27, p = 0.150).

38

Table 4: Number of raptor species seen during road transect counts and number of individuals per 100 km transect in spring and

autumn 2010.

Scientific name English name German name Dutch name spring autumn

n n/100 km n n/100 km Gyps fulvus Griffon Vulture Gänsegeier Vale Gier 2 0.1 0 0.0 Pandion haliaetus Osprey Fischadler Visarend 0 0.0 1 0.0 Aquila chrysaetos Golden Eagle Steinadler Steenarend 2 0.1 2 0.1 Circaetus gallicus Short-toed Eagle Schlangenadler Slangenarend 2 0.1 5 0.2 Hieraaetus pennatus Booted Eagle Zwergadler Dwergarend 1 0.0 10 0.4 Aquila fasciata Bonelli´s Eagle Habichtsadler Havikarend 0 0.0 2 0.1 Milvus milvus Black Kite Schwarzmilan Zwarte Wouw 2 0.1 3 0.1 Circus aeruginosus Marsh Harrier Rohrweihe Bruine Kiekendief 11 0.5 14 0.6 Circus pygargus Montagu´s Harrier Wiesenweihe Grauwe Kiekendief 3 0.1 6 0.3 Buteo rufinus Long-legged Buzzard Adlerbussard Arendbuizerd 1 0.0 25 1.1 Pernis apivorus Honey Buzzard Wespenbussard Wespendief 0 0.0 1 0.0 Accipiter nisus Sparrowhawk Sperber Sperwer 0 0.0 2 0.1 Elanus caeruleus Black-winged Kite Gleitaar Grijze Wouw 0 0.0 1 0.0 Falco tinnunculus Kestrel Turmfalke Torenvalk 20 1.0 10 0.4 Falco naumanni Lesser Kestrel Rötelfalke Kleine Torenvalk 38 1.9 21 0.9 Falco biarmicus Lanner Falcon Lannerfalke Lannervalk 6 0.3 9 0.4 F. tinnunculus/naumanni Kestrel/Lesser Kestrel Turm/Rötelfalke Toren/Kleine Torenvalk 3 0.1 7 0.3 Falco spec. 0 0.0 1 0.0 Raptor spec. 0 0.0 7 0.3 Athene noctua Little Owl Steinkauz Steenuil 0 0.0 10 0.4 sum 91 4.5 137 6.1

38

39

distance from the road [m]

0 100 200 300 400 500 600 700 800 900 1000

num

ber

of r

apto

r ob

serv

atio

ns

0

20

40

60

80

Fig. 3.8: Frequency distribution of the distance from the road transect line of raptor

observations (n = 195) in East-Morocco 2010.

Fig. 3.9: Number of raptors observed during road transects in the course of the day (local

time = UTC). Given above are the number of days during which transects were counted and

the total observation minutes per hour of the day. Dark grey bars indicate approximately

sunrise and sunset.

hours of the day

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

num

ber

of r

apto

rs/h

our

0

5

10

15

20

25

30

17

6191

17429

20550

21625

21675

21524

23840

22730

14428

797

229

number of dayssum minutes

40

3.3 Habitat selection during stopover

Satellite telemetry data and Globcover digital land cover map

A comparison of stopover sites used by Montagu´s Harriers with Morocco as

reference area (excluding southern provinces, but including a part of Algeria to cover

the whole stopover area; blue polygon in Fig. 3.10) showed that habitats (Globcover

land cover categories) were not chosen randomly (Fig. 3.11). Habitat composition in

the three stopover areas (spring west, spring east, autumn east; see Fig. 3.3)

differed significantly from the habitat composition of the reference area (Chi-squared

test for 12 habitat types with an availability in Morocco >2 %; reference area vs.

spring east: χ² = 23.923, df = 11, p = 0.013; reference area vs. spring west: χ² =

47.006, df = 11, p < 0.001; reference area vs. autumn east: χ² = 48.793, df = 11, p <

0.001; Fig. 3.10 and 3.11). In the eastern stopover area, in spring and autumn, the

land cover category ‘bare areas’ was overrepresented compared to the reference

area (Fig. 3.11B,C). All other categories were underrepresented in the stopover area

compared to the reference area. In the western spring stopover area, the vegetation

categories ‘rainfed cropland’, ‘mosaic cropland/vegetation’ and ‘sparse vegetation’

were overrepresented compared to the reference area (Fig. 3.11A). ‘Bare areas’,

‘closed to open shrubland’ and ‘mosaic vegetation/cropland’ were underrepresented

in the stopover area compared to the reference area.

To test if preferences were also consistent on a smaller scale level, I divided the

reference area in an eastern and a western part (Fig. 3.10 black polygons). The

presence of different habitat types at the spring stopover site in the west did not

differ significantly from the abundance in the western reference area (χ² = 17.370, df

= 11, p = 0.097; Fig. 3.12). Nevertheless, there was a trend of harriers using areas

with ‘rainfed cropland’, ‘mosaic cropland/vegetation’ and ‘sparse vegetation’ more

than proportionally available, unlike the other land cover categories.

The habitat composition at the spring stopover site in the east did not differ

significantly from the eastern reference area (χ² = 7.086, df = 11, p = 0.792, Fig.

3.12). In autumn, there was a significant difference between the habitat present at

the stopover site compared to the eastern reference area (χ² = 25.686, df = 11, p =

0.007; Fig. 3.12). Then, harriers used an area where the category ‘bare areas’ was

overrepresented compared to the eastern reference area. Other habitat categories

were used to a lesser extent than proportionally available in the reference area.

41

To estimate how good inferences on habitat availability and use based on the

Globcover map are, ground truthing with prey transect habitat categories was

conducted. For 1316 prey transect start and end points from our spring and autumn

trips, the value of the Globcover raster was obtained and compared to the habitat

type noted in the field (Fig. 3.13). For Globcover raster cell values denoting different

types of agricultural land, we always categorized vegetation during prey transect

counts as farmland. But these were only 6 % of transects we noted as farmland. For

94 % of what we also noted as farmland, Globcover gives values for ‘mosaic forest-

shrubland/grassland’ (1 %) ‘sparse vegetation’ (27 %) or ‘bare areas’ (65 %). ‘Mosaic

forest-shrubland/grassland’ was in the field mainly determined as ‘depression’ (64

%), as ‘farmland’ (14 %), or a mixture of both (18 %), and once as ‘natural steppe’ (5

%). In the field, we designated the Globcover category ‘closed to open shrubland’

always as our category ‘trees’. We classified ‘sparse vegetation’ mainly as ‘farmland’

(40 %), ‘Halfa steppe’ (23 %) and ‘natural steppe’ (20 %), as well as some other

categories. The Globcover type ‘bare areas’ also consisted in the field of many

categories, mainly ‘natural steppe’ (45 %), ‘Halfa steppe’ (19 %), ‘farmland’ (12 %)

and ’Artemisia steppe’ (7 %).

42

Fig. 3.10: Reference areas for comparison of habitat composition. Blue polygon: Morocco,

excluding southern provinces and including a small part of west Algeria. Reference areas

west and east Morocco are lined in black. Green lines encircle spring stopover sites and red

lines the autumn stopover site. Lines indicate 50 % (inner) and 90 % (outer) volume contours

of kernel densities of Montagu´s Harrier fixes in stopover areas between 2006 and 2010.

43

Fig. 3.11: Habitat availability in the whole reference area (black, see Fig. 3.4) compared to

habitat in the three stopover areas (grey, Fig. 3.3) for the most important Globcover land

cover types (availability in Morocco >2 %). A: spring west, B: spring east and C: autumn east.

Fig. 3.12: Habitat availability in the two reference areas east and west (black, see black lined

areas in Fig. 3.4) compared to habitat in the stopover areas (grey) in the east (spring and

autumn) and west (spring) for the most important Globcover land cover types (availability in

Morocco >2 %).

Habitat percentages [%]0 20 40 60 80 100

availableused

Habitat percentages [%]0 20 40 60 80 100

Rainfed croplands

Mosaic croplands/Vegetation

Mosaic vegetation/Croplands

Mosaic Forest-Shrubland/Grassland

Closed to open shrubland

Sparse vegetation

Bare areas

Habitat percentages [%]0 20 40 60 80 100

Rainfed croplands

Mosaic croplands/Vegetation

Mosaic vegetation/Croplands

Mosaic Forest-Shrubland/Grassland

Closed to open shrubland

Sparse vegetation

Bare areas

A B

C

East Morocco

Habitat percentages [%]

0 20 40 60 80 100

Rainfed croplands

Mosaic croplands/Vegetation

Mosaic vegetation/Croplands

Mosaic Forest-Shrubland/Grassland

Closed to open shrubland

Sparse vegetation

Bare areas

availableused springused autumn

West Morocco

Habitat percentages [%]

0 20 40 60 80 100

availableused

44

Fig. 3.13: Ground truthing of Globcover digital land cover map (Globcover Source Data: ©

ESA / ESA Globcover Project, led by MEDIAS-France/Postel) with habitat types noted in prey

transect counts in East-Morocco 2010. Of each Globcover category, the sample size (number

of prey transect reference points) is given in brackets behind the category name.

Habitat selection: field data

Compositional analysis of habitat selection of all Montagu´s Harriers observed in

spring (n = 73) revealed that farmland was the only significantly preferred habitat

(Compositional analysis: λ = 0.041, p = 0.01, Fig. 3.14A). Harriers also used natural

steppe, Halfa steppe and Artemisia steppe, but to a lower proportion than available.

Villages and anti-erosion management areas were avoided. The same trend could

be shown in autumn, where Montagu´s Harriers (n = 11) preferred farmland

(Compositional analysis: λ = 0.002, p = 0.01, Fig. 3.14B). Like in spring, no harriers

were observed in villages and anti-erosion areas.

As there were not many observations during transect counts, these preferences

reflect mainly the choice of roosting habitat. Using all birds observed at roosts in

spring and autumn together (n = 60), Montagu´s Harriers preferred farmland

significantly (Compositional analysis: λ = 0.0001, p = 0.01, Fig. 3.15A). Except for

natural steppe, which was used for roosting to a lower proportion than available, all

other habitat types were avoided as roosts. If only individuals observed outside

roosts (n = 24) for both seasons combined were considered, farmland, natural

steppe, Artemisia steppe and Halfa steppe were significantly preferred, supposedly

0 5 10 15 20 25 30 35 40 45 80 100

rainfed croplands (2)

mosaic croplands/vegetation (8)

mosaic vegetation/croplands (4)

mosaic forest-shrubland/grassland (22)

closed to open shrubland (4)

sparse vegetation (145)

bare areas (1131)

anti-erosionArtemisia steppedepressionfarmlandHalfa stepperockssteppetreeswadi

45

representing preferred hunting habitats (Compositional analysis: λ = 0.0002, p =

0.01, Fig. 3.15B). Montagu´s Harriers also avoided anti-erosion areas and villages

during the day.

Using information on habitat degradation noted with Montagu´s Harrier observations

during road transect counts, it could be shown that harriers (n = 22) significantly

preferred habitats that were not degraded (Compositional analysis: λ = 0.010, p =

0.01, Fig. 3.16).

Fig. 3.14: Habitats used by Montagu´s Harriers observed during stopover in East-Morocco

2010 (used) compared to reference habitat types noted every 5 km during road transect

counts (available). A: spring, N = 73 birds. B: autumn, N = 11. Asterisks indicate preference

based on compositional analysis.

B

habitat percentages

0 20 40 60 80

A

habitat percentages

0 20 40 60 80

anti-erosion

farmland

natural steppe

Artemisia steppe

Halfa steppe

village

availableused

***

46

Fig. 3.15: A: Habitats used by Montagu´s Harriers (N = 60) at roosts in spring and autumn in

East-Morocco 2010 (used), compared to reference habitat types noted every 5 km during

road transect counts (available). B: Habitats used by Montagu´s Harriers (N = 24) outside

roosts in spring and autumn in East-Morocco 2010 (used), compared to reference habitat

types noted every 5 km during road transect counts (available).

Fig. 3.16: Proportion of Montagu´s Harriers observed in East-Morocco 2010 (n = 22) vs. the

proportion of different degradation categories (see 2.3) of habitats available during transect

counts (reference habitat noted every 5 km). Values above line through origin (f(x) = x)

indicate preference, values below the line avoidance.

A

habitat percentages

0 20 40 60 80 100

anti-erosion

farmland

natural steppe

Artemisia steppe

Halfa steppe

village B

habitat percentages

0 20 40 60 80 100

availableused

***

Proportion of degradation categories of habitat available [%]

0 10 20 30 40 50 60 70

Pro

port

ion

of M

onta

gu´s

Har

riers

obs

erve

d [%

]

0

10

20

30

40

50

60

70

no degradation

much degradation

few degradation

47

3.4 Prey abundance and prey choice

Prey abundance in East-Morocco

In total, 7141 potential prey birds, 88 reptiles and amphibians, 20 mammals, 3054

small mammal and reptile holes and 7410 insects were observed. In autumn, we

separated small mammal and reptile holes: 351 reptile holes were identified.

The Shannon-Weaver diversity index for potential prey bird species was 2.22

(N = 2932, 39 species) in spring and 2.09 (N = 2906, 26 species) in autumn; both

reflecting medium values of diversity. The evenness was 0.61 and 0.64, respectively,

showing that individuals of potential prey birds were not evenly distributed over

species.

This was also visible in the dominance structure (relative abundance of a species in

comparison to other species) of prey bird species in spring and autumn (Fig. 3.17

and Fig. 3.18). Most species were subrezedent (dominance <1 %, spring: 28

species, autumn: 17) or rezedent (1-2 %, spring: 2, autumn: 2). In spring, 3 species

were subdominant (2-5 %). In both seasons, 5 species were dominant (5-10 %).

Among those were in both cases Temminck´s Lark, Lesser Short-toed Lark, and

Barn Swallow. In spring, Short-toed Larks were by far the most abundant

(eudominant >10 %) species. The two most abundant species in autumn were

Calandra Lark and Short-toed Lark. In spring, most of the potential prey birds that we

observed were local breeding birds. Migrating songbirds were only observed

occasionally, not contributing a lot to potential prey bird abundance in East-Morocco.

In autumn, we observed big groups of larks, mainly Calandra Lark and Short-toed

Lark, which is also reflected in the dominance structure.

48

Fig. 3.17: Dominance structure of potential prey bird species observed during prey transect

counts in East-Morocco in spring 2010. N = 39 species. For scientific names see Appendix 5.

dominance

2 4 6 8 10 40

Brown-throated MartinHouse Martin

RedstartBlackbirdGoldfinch

Serin Whitethroat

Black WheatearMotacilla spec

Tawny PipitWood WarblerZitting Cisticola

Sand MartinThick-billed LarkHouse Sparrow

WhinchatBar-tailed Lark

Red-throated PipitSeebohm s Wheatear

Bee-eaterCorn Bunting

Willow WarblerDesert Wheatear

Red-rumped WheatearTrumpeter Finch

SkylarkNorthern Wheatear

Crested LarkHoopoe Lark

Yellow WagtailThekla Lark

Calandra LarkSpanish Sparrow

Lesser Short-toed LarkBarn Swallow

Temminck s LarkCommon Swift

Short-toed Lark

49

Fig. 3.18: Dominance structure of potential prey bird species observed during prey transect

counts in East-Morocco in autumn 2010. N = 26 species. For scientific names see Appendix

5.

Temporal and spatial variation in prey abundance

In spring, significantly more potential prey birds were observed during transect

counts than in autumn (GLM, F = 9.027, p = 0.003, Fig. 3.19B). During both

seasons, we counted more transects in the morning between 7:00 – 11:00 h (Fig.

3.19A). Highest numbers of birds in spring were observed in the early morning, with

decreasing numbers towards the hotter time of the day and again an increase in the

afternoon. The same was true in autumn, where highest numbers of birds were

counted between 7:00 – 9:00 h in the morning and 15:00 – 17:00 h in the afternoon.

The peak between 12:00 – 13:00 h in spring resulted from only five transects

counted in this hour, of which four were in more profitable habitats supporting

proportionally more birds. Nevertheless, the abundance of prey birds was not

significantly influenced by time (F = 1.840, p = 0.175). There was no variation of prey

bird abundance due to a varying frequency of transect kilometers counted over the

dominance

0 5 10 15 20 35

Rufous Bush RobinSand MartinWhitethroat

Tristram s WarblerScrub Warbler

Seebohm s WheatearChaffinch

Common SwiftGoldfinch

White-crowned WheatearDupont s Lark

Desert WheatearCrested Lark

Bar-tailed LarkThick-billed Lark

Desert LarkNorthern Wheatear

Hoopoe LarkRed-rumped Wheatear

Trumpeter FinchThekla Lark

Temminck s LarkBarn Swallow

Lesser Short-toed LarkCalandra Lark

Short-toed Lark

50

day (F = 1.579, p = 0.209). Unfortunately, transect length itself influenced the

number of potential prey birds counted (F = 114.823, p < 0.001).

Fig. 3.19: A: Total length of counted prey transects per hour of the day in spring and autumn.

B: Potential prey birds per kilometer transect over the hours of the day in spring and autumn.

Local time = UTC. Dark grey bars indicate approximately sunrise and sunset.

To evaluate the spatial differences in prey abundance during spring and autumn

stopover of Montagu´s Harriers in East-Morocco 2010, we divided the study area in

11 regions, which had specific habitat and landscape characteristics in common (see

Fig. 2.3, Table 5).

The Shannon-Weaver diversity index of bird species per region varied

between 0.64 in the wooded Bni Snassen mountains (area 2) and 2.32 in the rocky

steppe around Bouarfa and Mengoub (area 9; Table 5). All regions in steppe areas

on the high plateaus showed medium values around 2, indicating that the diversity is

not poor in these regions. The evenness ranged from 0.53 in the steppe around Ain

Benimathar and in the farmland close to Oujda (area 1 and 3) to 0.92 in the Bni

Snassen mountains (area 2). Most of the areas showed high values, indicating that

individuals were not even distributed among species. The abundance of potential

prey birds differed between the regions (GLM, F = 12.629, p = < 0.001). Most

potential prey birds were observed in regions dominated by steppe vegetation

(spring: area 1, 7 and 9; autumn: area 5, 1 and 9; Fig. 3.20). Highest densities of

B

hours of the day

06 07 08 09 10 11 12 13 14 15 16 17 18 19

pote

ntia

l pre

y bi

rds/

km

0

20

40

60

80

100A

hours of the day

06 07 08 09 10 11 12 13 14 15 16 17 18 19

tota

l tra

nsec

t len

gth

[km

]

0

10

20

30

40

50

springautumn

51

insects were also counted in steppe vegetation (spring: area 1 and 5; autumn: area 5

and 1). High numbers of insects refer mainly to beetles. Small mammal holes were

more abundant in autumn, e.g. in area 4, which had the highest number with 76

holes per transect-km in autumn, and 5 holes/transect-km in spring. Reptiles,

amphibians and small mammals were only observed occasionally.

Summing up, the regions on the high plateaus, dominated by steppe vegetation,

showed a high abundance of potential prey birds in both seasons. There are several

species that may be of importance as potential prey, but most notably was the

abundance of Short-toed Larks in both seasons. Satellite tagged Montagu´s Harriers

used mainly areas in regions with higher potential prey availability (area 1, 6, 7, 8; cf.

Fig. 3.4).

52

Table 5: Prey transects per area, area name and characteristics. Sum of birds observed and numbers of bird species per area, as well

as Shannon-Weaver Index (Hs) and Evenness (E) for each area, spring and autumn combined. Positions of areas see Fig. 2.3.

area name characteristics n transects length n birds n birds/km n species Hs E

1 Ain Benimathar high plateau, steppe 230 113.75 2841 24.98 45 2.01 0.53

2 Bni Snassen mountains, trees 2 0.82 3 3.66 2 0.64 0.92

3 Oujda farmland, crop 3 1.58 121 76.47 15 1.43 0.53

4 Jerada hills, steppe, trees 11 3.81 38 9.97 10 1.83 0.79

5 Taourirt steppe 51 17.75 640 36.06 18 1.59 0.77

6 Rekkam plateau high plateau, steppe 43 16.91 254 15.02 17 2.20 0.78

7 Maatarka high plateau, steppe 45 20.07 606 30.19 18 1.64 0.57

8 Tendrara high plateau, steppe 97 38.10 438 11.50 21 2.22 0.73

9 Bouarfa-Mengoub rocky steppe 122 55.58 978 17.60 35 2.32 0.65

10 Atlas mountains 38 16.91 54 3.19 13 2.21 0.82

11 Bouanane-Errachidia sandy, rocky 12 9.58 33 3.44 12 2.12 0.85

52

53

mean number per km0 5 10 15 20

mean number per km0 20 40 60 80

mean number per km0 10 20 30 40 50 60 70 80

prey birds

insects

mammal holes

reptiles/amphibians

mammals

mean number per km0 5 10 15 20

mean number per km0 2 4 6 8

mean number per km0 20 40 60 80 100

prey birds

insects

mammal holes

reptiles/amphibians

mammals springautumn

1 32

4 5 6

mean number per km0 2 4 6 8 10 12 14 16 18

prey birds

insects

mammal holes

reptiles/amphibians

mammals

mean number per km0 5 10 15 20 25

mean number per km0 5 10 15 20 25 30

prey birds

insects

mammal holes

reptiles/amphibians

mammals springautumn

mean number per km0 10 20 30 40 50

7 8

10 11

mean number per km0 5 10 15 20 25 30 35 40

9

Fig. 3.20: Mean number of prey categories per region. Note the different scales of the x-axes.

Positions of regions see Fig. 2.3.

54

Prey abundance in different habitats

Habitat type had a significant influence on the abundance of potential prey birds

(GLM, F = 10.888, p = 0.002). In spring, highest numbers of potential prey birds per

kilometer transect were observed in farmland and depressions (Fig. 3.21A). The

abundance was also high in natural steppe, Halfa steppe and Artemisia steppe,

containing more than 20 birds/km. Fewer prey birds were counted in anti-erosion,

wooded and rocky areas. The number of insects, mostly beetles, in spring was

highest in the steppe habitats. The very high number of more than 160 insects/km in

Artemisia steppe was strongly influenced by counts in one area with many beetles.

In autumn, most birds/km transect were observed in farmland and Artemisia steppe

(Fig. 3.21B). Relatively high densities of potential prey birds were also counted in

natural steppe, Halfa steppe and close to wadis, where often small puddles of water

were available. Lowest counts in autumn were in depressions and anti-erosion

areas. Insects were most abundant in steppe habitats, as they had been in spring.

Small mammal holes were more numerous in farmland and depressions in autumn

than in spring.

The number of potential prey birds decreased in more degraded habitats (F = 4.040,

p = 0.007; Fig. 3.22). The same could be seen for the number of observed small

mammal holes and of insects in autumn (Fig. 3.22B). Only the number of insects in

spring was higher in more degraded areas than in areas that were less degraded

(Fig. 3.22A).

Satellite tagged Montagu´s Harriers preferred farmland and steppe habitats for

hunting (cf. 3.3, Fig. 3.15). Combining these results, harriers chose hunting habitats

with higher availability of potential prey birds. They also avoided heavily degraded

habitats which contain less potential prey (cf. 3.3, Fig. 3.16).

55

Fig. 3.21: Number of potential prey/km prey transect counted, in the different habitat types

during spring (A) and autumn (B) 2010. Note the different scales.

Fig. 3.22: Number of potential prey/km prey transect counted, in the different degradation

categories in spring (A) and autumn (B) 2010. Categories see 2.3. Note the different scales.

Prey choice during spring stopover

All pellets originated from a roost at a farm south of Ain Benimathar, used by

approximately 10 Montagu´s and 10 Marsh Harriers on 17 and 22 April 2010.

Analyzing 21 pellets of Montagu´s Harriers (114 prey items were identified) revealed

that the main prey were passerine eggs and birds, small mammals and reptiles (Fig.

3.23).

A

number/km

0 10 20 30 40 50 60 175

anti-erosion

depression

farmland

natural steppe

Artemisia steppe

Halfa steppe

rocks

trees prey birdsinsectsmammal holesreptiles

B

number/km

0 10 20 30 40 50

anti-erosion

depression

farmland

natural steppe

Artemisia steppe

Halfa steppe

wadi

A

degradation

0 1 2 3

num

ber/

km

0

20

40

60

80

prey birdsinsectsmammal holesreptiles

B

degradation

0 1 2 3

num

ber/

km

0

5

10

15

20

25

30

56

Egg shell remains made up nearly half of the average volume and weight of the

pellets (Fig. 3.23A). Also important proportions of bones, feathers, reptile scales,

beetles and mammal hair were found. The proportions of prey items according to

estimated volume in pellets and the weighed proportion in pellets did not differ

significantly (Fisher´s Exact Test, p = 0.815).

Referring to minimal numbers of prey categories, small prey items like

beetles and eggs made up 81 % of total numbers (Fig. 3.23B). Concerning biomass,

however, birds and eggs made up 81 %, small mammals accounted for 11 %,

reptiles and beetles added only little (Fig. 3.23B). The average proportion of prey

items based on the number counted in pellets and estimated biomass of the

categories did differ significantly (Fisher´s Exact Test, p < 0.001).

Fig. 3.23: A: Average proportion of mean estimated volume in pellets and weight of different

pellet fractions separated according to different prey categories. B: Average proportion of

(minimum) number and estimated fresh biomass of different prey categories in pellets. n = 21

pellets found at a roost south of Ain Benimathar, Morocco (used by 10 individuals) on 17 and

22 April 2010.

B

number biomass

aver

age

prop

ortio

n in

die

t [%

]

0

20

40

60

80

100

eggsbeetlesbirdsreptilesmammals

A

volume weight

aver

age

prop

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egg shellsbonesfeathersreptile scalesbeetlesmammal hairplant material

57

4. Discussion

Importance of Montagu’s Harriers’ stopover sites in West- and East-Morocco

revealed by satellite telemetry

Satellite telemetry proved to be a useful tool to analyze stopover behavior of

Montagu´s Harriers. Around ¾ of northwest-European satellite-tagged Montagu’s

Harriers reached their wintering and breeding areas, on a route via Spain (see 1.).

The “Spanish” route is thereby one of the most important migratory pathways for

Montagu’s Harriers in the Western Palaearctic (Trierweiler & Bijlsma in prep.,

Trierweiler 2010). Here, we show that on average more than half of Montagu’s

Harriers using this pathway stopped over in Morocco, with almost 80 % of individuals

in spring and around 40 % in autumn.

Supposing that the proportions of satellite-tagged Montagu’s Harriers using

the stopover site are representative for the whole western European Montagu’s

Harrier breeding populations (including southern European ones), we can conclude

that more than 8,500 breeding pairs or 28,000 individuals of the total 11,500

breeding pairs (36,800 individuals) migrating on this pathway may use Morocco as

stopover site (Trierweiler & Bijlsma in prep., Trierweiler 2010, this study). Morocco

may, however, be more important as stopover site for Montagu’s Harriers from

northern Europe that migrate approximately 5000 km, than for southern European

birds that migrate only around 2500 km to their wintering areas. Actual numbers of

Montagu’s Harriers stopping over may therefore be much lower than the above

estimate, taking into account that the Spanish Montagu’s Harrier population is the

largest in western Europe (Mebs & Schmidt 2006, Trierweiler & Bijlsma in prep.).

Differential use of the stopover area Morocco during autumn and spring migrations

The higher importance of Morocco as stopover site in spring than in autumn could be

explained by e.g. the possibilities of refueling in Europe during autumn migration,

compared to arrival in Morocco after the Sahara desert crossing in spring. In autumn,

prey may be widely available on the migration through Europe: populations of small

mammals in Europe may reach their highest numbers during the annual cycle in

autumn (Dijkstra et al. 1995). In spring, however, Montagu’s Harriers leave the

Sahelian wintering quarters at the end of the dry season, when food sources are

probably at their lowest level during the annual cycle, and they cross the desert,

which may be food-deprived on wide stretches. The harriers, potentially facing

58

energetic bottlenecks, may then encounter the first possible stopover area in

Morocco. Several other potential reasons for the higher importance of Morocco

during spring migration may be thought of. For instance, differences in weather

circumstances may influence migration and stopover dynamics in Montagu’s

Harriers. Also, the exceptionally high food abundance in (East-)Morocco in spring

may be very attractive for Montagu’s Harriers, whereas food abundance in (East-

)Morocco is much lower in autumn and may thereby be not especially attractive

compared to stopover sites in Europe. Independent of the number of potential prey

birds the chance to catch an individual bird must be higher in spring e.g. incubating

females on nests, than in autumn when larks were often seen in big groups. Another

aspect leading to stopover may be a social component. Montagu´s Harriers were

found to use communal roosts during stopover in East-Morocco. Further studies are

needed to investigate the differential importance of Morocco during spring and

autumn migration, and the attractiveness of Morocco compared to European areas

as stopover site for Montagu’s Harriers.

Stopover phenology and site faithfulness

On average, satellite-tagged northwest-European Montagu´s Harriers stopped over

in Morocco for 9 days, in spring arriving around 12 April, in autumn around 17

September. It could have been expected that Montagu´s Harriers stop over for fewer

days in spring, because their migration is shorter in spring than in autumn

(Trierweiler 2010). However, the duration of stopover did not differ between the

seasons. Maybe birds make less stopover days in other areas in spring or migrate

slower in autumn. For several birds that were tracked in subsequent years, site

faithfulness to the stopover areas in Morocco could be shown. The satellite-tagged

Dutch adult male Franz for example always used the same stopover area in East-

Morocco during spring migration (except for one spring, when he did not stop over,

2007 - 2010). Danish adult female Mathilde was the only satellite-tagged harrier of

whom we documented the use of the western Moroccan stopover area in spring and

the eastern area in autumn (2009 - 2010). Strong site fidelity to East-Morocco during

stopover could also be shown for Dutch/German adult female Merel, who returned to

her Moroccan stopover area in six seasons (spring and autumn 2006 - 2009). This

bird also showed a strong site fidelity in the wintering grounds where she visited the

same home ranges in three consecutive years (Trierweiler 2010). The high site

59

faithfulness to the stopover site indicates a high degree of migratory connectivity

between breeding, stopover and wintering populations of Montagu’s Harriers. This

connectivity may cause carry-over effects of ecological conditions during stopovers

in Morocco to subsequent seasons (e.g. wintering, breeding). The existence of such

carry-over effects for Montagu’s Harriers should be investigated in future studies.

Distribution and abundance of Montagu´s Harriers in East-Morocco

East-Morocco has not received much attention in ornithological studies as yet. It is a

region with little infrastructure, which is neither visited by many tourists nor the

destination of many scientific expeditions. The lack of observations of Montagu´s

Harriers in this region reported in ornithological literature is clearly an effect of the

absence of observers, and not of the absence of birds (Thevenot et al. 2003, cf. this

study). Additionally, field observations are dependent on i) chance, ii) length and

intensity of transect counts, iii) number of times passing through the same areas

during road transect counts. This highlights the importance of satellite telemetry

studies that are able to discover and identify areas of ecological importance for birds,

also in the absence of local observers or previous reports from the field.

During road transect counts the detection probability of birds is generally dependent

on the distance from the road as well as on the size of the bird. I have shown that the

detection of raptors during Moroccan road transects decreased after 100 m and that

92 % of observations lay within 400 m. Future analysis should incorporate

calculations of the detection probabilities of different bird species, taking into account

their size and behavior. This could be conducted if more observations were

available. That no significant day-time variation in the number of raptors counted was

found, could also be biased by the low sample size. Other studies reported that

during road transect counts raptor observations were influenced by time of day

(Thiollay 2006).

Of the total raptor density of 5.3 raptors per 100 km road transect in East-

Morocco during migration periods, 0.2 per 100 km road transect were Montagu´s

Harriers. The resolution of these road transects may have been too low to find

significant differences between autumn and spring numbers, which have been

identified in the satellite telemetry data. In the wintering areas, higher road counts of

Montagu’s Harriers have been reported: 0.43 and 0.52 Montagu´s Harriers per 100

60

km in Niger in 2006 and 2007 (Trierweiler & Koks 2009) and 0.7 to 0.9 in the western

Sahel 2003-2004 (Thiollay 2006). These differences in densities may be a result of

the temporal and spatial patterns of use of the area. Montagu’s Harriers travel

through Morocco on a relatively wide front and in a relatively wide time window of

about four weeks. In the Sahel, on the other hand, wintering harriers spend several

months in restricted areas and show strong fidelity to wintering home ranges

(Trierweiler 2010).

Apart from road transects, observing Montagu’s Harriers in the wintering

areas may not be as difficult as in the stopover site, because of the higher

detectability of great numbers of harriers, which accumulate in communal roosts

(Trierweiler & Koks 2009). In Morocco, detecting (small) roosts or even individual

harriers proved very difficult without tracking satellite tagged harriers.

Habitat selection of Montagu’s Harriers during stopover in Morocco

Based on analyses of Montagu’s Harrier satellite telemetry data together with a

digital land cover map (Globcover), we conclude that harriers chose their stopover

sites not randomly within the reference area, which comprised parts of Morocco and

Algeria and was dominated by ‘bare areas’. In the western Moroccan stopover area,

harriers selected different agricultural habitat types, whereas in the eastern area,

they preferred ‘bare areas’. According to the digital map, the whole west of Morocco

was dominated by agricultural fields in contrast to the east, which was dominated by

‘bare areas’. This explains why habitat selection was not significant when based on

habitat abundance within smaller, western and eastern reference areas, respectively.

The harriers’ preference for either agricultural habitat types (located in the west) or

‘bare areas’ (in the east) seems to be inherent in their migratory route choice through

either West- or East-Morocco.

The ecological significance of ‘bare areas’ as harrier habitats was surprising.

However, ground truthing of the Globcover land cover categories by habitat

categories noted in the field in East-Morocco revealed that ‘bare areas’ were

composed of multiple habitat types, 71 % of these being steppe habitats and 12 %

farmland. The ground truthing thus shows the limited usefulness of the Globcover

land cover map. Classifying the eastern Moroccan steppe as ‘bare areas’ by

Globcover (based on satellite scenes) may relate to how open and sparsely

vegetated this steppe is. In the light of ground truthing, our results most probably

61

indicate a preference of the harriers for mainly natural steppe habitats in East-

Morocco. The classification of habitat types in the field could also cause bias, but

was always conducted in the same way to reduce this.

Montagu´s Harriers observed in East-Morocco preferred farmland habitats.

This preference was mainly based on the use of these habitats for roosting. For

hunting, the restricted number of observations indicated that steppe habitats were

more important than farmland habitats. These direct observations clarify the

conclusions from the telemetry/remote sensing data and additionally revealed that

harriers prefer non-degraded over degraded habitats. The latter indicates the

importance of conservation actions to counteract degradation of steppe and farmland

habitats in East-Morocco.

The differential use of the western and eastern stopover site, with the

western site being used mostly in spring and less in autumn (in contrast to the

eastern site being used in both seasons), may be related to the different habitat

types (agricultural vs. natural) dominating these areas.

Additional to the low accuracy of the Globcover land cover map, another

factor limiting inference from digital maps on habitat use of satellite tracked birds is

the low precision or inaccuracy of satellite fixes. Future analyses will make use of

very accurate and much more precise data from GPS loggers mounted on

Montagu’s Harriers. These data allow also a much higher temporal resolution.

Because of the drawbacks of current telemetry and remote sensing data

analyses, traditional fieldwork was not only important for ground truthing but also for

direct observations of habitat preferences of Montagu’s Harriers.

Prey abundance and prey choice

The availability of potential prey birds was highest in regions that were also used by

satellite tagged Montagu´s Harriers. Mainly the steppe on the high plateaus was

holding great amounts of potential prey. We could show that Montagu´s Harriers

chose those habitat types that were rich in potential prey for hunting. Poorer habitat

types and degraded habitats were avoided by the observed harriers.

The diet of Montagu’s Harriers during stopover in East-Morocco was dominated by

resident songbirds. Pellet analysis revealed that songbirds, their eggs and nestlings

were the most important prey items, accounting for approximately 67 % of fresh

(wet) biomass eaten. The main food source of Montagu´s Harriers in the breeding

62

area in the Netherlands is the Common Vole (Microtus arvalis; Koks et al. 2007).

Other common prey items are songbirds like Sky Lark (Alauda arvensis), Meadow

Pipit (Anthus pratensis) and Yellow Wagtail (Motacilla flava; Koks et al. 2007).

Harriers around Madrid feed on lagomorphs and lots of other prey types during the

breeding season (Arroyo 1997). At the wintering sites the main prey is non-migratory

grasshoppers (Trierweiler et al. 2008).

Keeping in mind that during the wintering period grasshoppers and locusts

are the most important prey items, we expected Montagu´s Harriers to feed on them

in Morocco, too. However, during our field expeditions, we observed grasshoppers

only occasionally. Arroyo (1997) named the Montagu´s Harrier an “opportunistic

specialist”, specializing on the best available and catchable food. This seems to hold

true also for prey choice during stopover, where mainly songbirds were eaten, but

also reptiles, mammals and insects were common prey items.

Threats for Montagu´s Harriers in East-Morocco and conservation and management

implications

The main threats for the local biodiversity in Morocco are human population growth

and resulting processes as deforestation and overgrazing:

“Population growth, the exponential demand on agricultural lands, together

with the collective status of land expanses, have resulted in deforestation

and appropriation of lands to cultivate cereals. The loss [of land] is

believed to be roughly 65 000 hectares[.] 3 to 5 times the recommended

animal charge [put additional pressure on the landscape].”

The National Environment Observatory of Morocco

Additionally, ecological changes because of missing rainfalls during winter are

accelerating degradation. Those changes not only have impacts on local breeding

birds, but can also influence or threaten long-distance migrants like the Montagu´s

Harrier. As predators raptors are dependent on a well functioning food chain.

Changing conditions that influence populations of prey animals like songbirds,

reptiles, small mammals and big insects also have an effect on their predators.

In the field, bullet casings were only encountered in a small number of cases.

In autumn, we observed a hunting party, searching a reserve west of Bouarfa,

63

probably to hunt Houbara Bustards (Chlamydotis undulata). Only one shot Stone

Curlew (Burhinus oedicnemus) was found in autumn. No other hints of illegal

persecution or hunting of Montagu’s Harriers or other bird species were encountered

during our field trips. This is consistent with the statements of local foresters and

birders who judged illegal hunting to be scarce or absent in East-Morocco.

During our field trips to East-Morocco, we could identify some factors that

may represent hazards to Montagu´s Harriers during stopovers. The encountered

ecosystems harbor habitat types, like steppe and extensive farmland that provide

most prey for Montagu’s Harriers. We show here that degradation lowers food

abundance and therefore could make circumstances for harriers on stopover less

favorable. Although seemingly remote and poor compared with other systems, the

steppe ecosystem is unique extending only over eastern Morocco and western

Algeria. Taking account of the results presented above, this region should

experience further conservation efforts in the future.

64

5. Summary

The Montagu´s Harrier (Circus pygargus) is a long-distant migratory raptor breeding

in the western Palaearctic and wintering south of the Sahara desert. Analyzing

satellite telemetry data of Montagu´s Harriers that migrated on a western route via

Spain revealed that during autumn migration, 41 % of tagged individuals used

stopover sites in Morocco. During spring migration, Morocco was even of greater

importance with 76 % of tracked Montagu´s Harriers stopping over. Analyses

revealed two major stopover areas in Morocco. One in western and one in eastern

Morocco, with the latter one being of greater importance because it was used by

more individuals and during spring as well as autumn migration. Satellite tagged

Montagu´s Harriers made on average 9-day stopovers in Morocco during spring and

autumn migration. Individuals that could be followed in consecutive years showed

site fidelity to the stopover areas in Morocco. During two field expeditions in East-

Morocco 2010, we observed Montagu´s Harriers during stopover, counted all raptors

during road transects, collected data on prey abundance by walking prey transects,

and gained insight in food choice by collecting pellets at communal roosts. In spring,

73 Montagu´s Harriers were observed, in autumn 11. Communal roosts discovered

in both seasons were used by Marsh and Montagu´s Harriers with about 10

individuals of each species. During road transect counts, the overall number of

raptors per 100 kilometer road transect was 5.3. Per 100 km transect, 0.1 Montagu´s

Harriers were observed in spring and 0.3 in autumn. Using a digital global land cover

map (Globcover), in comparison to Morocco as reference area the stopover sites of

Montagu´s Harriers were not chosen randomly in respect of habitat. In the eastern

stopover area, in spring and autumn, the land cover category ‘bare areas’ was

overrepresented compared to the reference area. In the western spring stopover

area, vegetation categories depicting farmland were overrepresented compared to

the reference area. However, ground truthing with prey transect habitat categories

revealed that the Globcover land cover categories were often different from the

habitat type noted in the field with ‘bare areas’ being reflected by steppe vegetation

and farmland in East-Morocco. Observed Montagu´s Harriers preferred farmland at

roosts. During the day, farmland, natural steppe, Artemisia steppe and Halfa steppe

were preferred, supposedly representing preferred hunting habitats. Montagu´s

Harrier observed in the field preferred habitats that were not degraded. The

availability of potential prey birds was highest in regions on the high plateaus. These

65

were the areas used by tagged Montagu´s Harriers during stopover. Most abundant

potential prey birds among others were Short-toed Larks that were encountered in

very high numbers during both seasons. In spring, more potential prey birds were

counted than in autumn. During spring stopover, breeding birds, their nests and

young seem to provide potential prey. Pellet analysis revealed that the main prey in

spring were passerine eggs and birds, small mammals and reptiles. In spring,

highest numbers of potential prey birds per kilometer transect were observed in

farmland and depressions. The abundance was also high in natural steppe, Halfa

steppe and Artemisia steppe, containing more than 20 birds/km. In autumn, most

birds/km transect were observed in farmland and Artemisia steppe, but also big

groups of larks, mainly Calandra Lark and Short-toed Lark, were observed outside

transects. The number of potential prey birds decreased in more degraded habitats.

Satellite tagged Montagu´s Harriers preferred farmland and steppe habitats

for hunting and therefore chose hunting habitats with higher abundances of potential

prey birds. They also avoided heavily degraded habitats which contained less

potential prey. The findings of the first field expeditions combined with analyses of

satellite telemetry data show that the steppes on the high plateaus of East-Morocco

are of great importance for Montagu´s Harriers during stopover in spring as well as in

autumn. Efforts should be made to preserve this unique landscape for long-distance

migrants using it as stopover site as well as for local breeding birds.

66

6. Zusammenfassung

Die Wiesenweihe (Circus pygargus) ist ein Langstreckenzieher, der in der westlichen

Palaearktis brütet und südlich der Sahara überwintert. Die Analyse von

satellitentelemetrischen Daten von Wiesenweihen, die über Spanien in ihre

Winterquartiere ziehen, ergab, dass während des Herbstzuges 41 % der

besenderten Wiesenweihen eine Rast in Marokko einlegten. Während des

Frühjahrszuges war Marokko von noch größerer Bedeutung, dort rasteten 76 % der

mit Sendern versehenen Wiesenweihen. Die Analysen zeigen zwei bedeutende

Rastgebiete in Marokko: eines im Westen, das andere im Osten des Landes.

Letzteres war von größerer Bedeutung, da es von mehr Individuen und sowohl

während des Frühjahrs- als auch des Herbstzuges genutzt wurde. Besenderte

Wiesenweihen rasteten in Marokko durchschnittlich 9 Tage. Individuen, die über

mehrere Jahre verfolgt werden konnten, zeigten Ortstreue in den Rastgebieten in

Marokko. Während zweier Feldexpeditionen nach Ost-Marokko 2010 beobachteten

wir Wiesenweihen während der Rast, zählten alle Greifvögel mit Hilfe von

Straßentransektzählungen, sammelten Daten zur Beuteverfügbarkeit mit Hilfe von

Beutetransektzählungen und gewannen einen ersten Eindruck in die

Nahrungszusammensetzung von Wiesenweihen anhand von Gewöllen, die bei

gemeinsamen Schlafplätzen gefunden wurden. Im Frühjahr wurden 73

Wiesenweihen beobachtet, im Herbst 11. Gemeinsame Schlafplätze, die während

der beiden Expeditionen gefunden wurden, wurden von Rohr- und Wiesenweihen,

jeweils rund 10 Individuen, gemeinsam genutzt. Während der

Straßentransektzählungen war die Anzahl der Greifvögel 5,3 pro 100 km Transekt.

0,1 und 0,3 Wiesenweihen pro 100 km wurden jeweils im Frühjahr und Herbst

gezählt. Betrachtet man eine digitale Landnutzungskarte (Globcover), so war die

Habitatzusammensetzung der Rastgebiete der Wiesenweihen verglichen mit

Marokko als Referenzgebiet, nicht willkürlich. Im östlichen Rastgebiet war sowohl im

Frühjahr als auch im Herbst die Landnutzungskategorie ‚kahle Gebiete‘ im Vergleich

zum Referenzgebiet überrepräsentiert. Im westlichen Rastgebiet waren im Frühjahr

Landnutzungskategorien, die landwirtschaftliche Nutzflächen wiederspiegeln, im

Vergleich zum Referenzgebiet überrepräsentiert. Ein Vergleich der

Landnutzungskategorien der digitalen Karte mit Habitatkategorien, die während der

Beutetransektzählungen notiert wurden, ein sogenanntes ‚Ground truthing‘, zeigte

jedoch, dass die Landnutzungskategorien oft nicht mit der Wirklichkeit

67

übereinstimmten. ‚Kahle Gebiete‘ waren in Ost-Marokko meist Steppen oder gar

landwirtschaftliche Nutzflächen. Die von uns beobachteten Wiesenweihen

bevorzugten landwirtschaftliche Nutzflächen als Schlafplatz. Während des Tages,

wahrscheinlich zur Jagd, bevorzugten sie landwirtschaftliche Nutzflächen und

Steppen aller Art. Die beobachteten Wiesenweihen bevorzugten Habitate, die nicht

degradiert waren. Die Verfügbarkeit von potentiellen Beutevögeln war in Regionen

mit hohen Plateaus am höchsten. Diese Gebiete wurden auch von den besenderten

Wiesenweihen zur Rast genutzt. Die häufigsten potentiellen Beutevögel waren

Kurzzehenlerchen, die wir sowohl im Frühjahr als auch im Herbst in großen

Anzahlen antrafen. Im Frühjahr wurden insgesamt mehr potentielle Beutevögel

gezählt als im Herbst. Während der Rast im Frühjahr scheinen Brutvögel, sowie

deren Eier und Junge potentielle Nahrungsquellen zu sein. Die Analyse von

Gewöllen, die während der Expedition im Frühjahr gesammelt wurden, zeigte, dass

die Hauptnahrung Singvogeleier und Singvögel, sowie Kleinsäuger und Reptilien

waren. Im Frühjahr wurde die höchste Dichte an potentiellen Beutevögeln in

landwirtschaftlichen Nutzflächen und Senken gefunden. Auch in verschiedenen

Steppenhabitaten waren mehr als 20 Vögel pro km Transekt zu finden. Im Herbst

wurden die höchsten Anzahlen an Beutevögeln pro km Transekt in

landwirtschaftlichen Nutzflächen und Artemisia Steppe gezählt. Auch beobachteten

wir große Gruppen von Kalanderlerchen und Kurzzehenlerchen außerhalb der

Transektzählungen. Die Anzahl der potentiellen Beutevögel war geringer in stärker

degradierten Habitaten.

Besenderte Wiesenweihen bevorzugten in Ost-Marokko landwirtschaftliche

Nutzflächen und Steppen als Jagdhabitat. Damit wählten sie während der Rast

Habitate mit hoher potentieller Nahrungsverfügbarkeit. Desweiteren vermieden

Wiesenweihen degradierte Habitate, die auch weniger potentielle Beute

beinhalteten. Die Auswertung der während der ersten beiden Expeditionen nach

Ost-Marokko gesammelten Daten zeigt, zusammen mit den satellitentelemetrischen

Daten, dass die Steppen auf den hohen Plateaus in Ost-Marokko von großer

Bedeutung für rastende Wiesenweihen sowohl während des Frühjahrs- als auch

während des Herbstzuges sind. Diese einzigartige Landschaft ist es wert, zukünftig

für Langstreckenzieher, die sie als Rastgebiet nutzen, und für lokale Brutvögel

erhalten zu werden.

68

7. Samenvatting

Grauwe Kiekendieven (Circus pygargus) zijn roofvogels die in Europa broeden en

zuidelijk van de woestijn in Afrika van de Sahel overwinteren. Analyses van

satellietzender data van Grauwe Kiekendieven, die via Spanje naar Afrika vliegen,

laten zien dat tijdens het najaarstrekmigratie 41 % van de gezenderde vogels een

stop maakte in Marokko. Tijdens de voorjaarstrek was Marokko van nog grotere

betekenis, omdat dan 76 % van de gezenderde Grauwe Kiekendieven daar een tijdje

hun trek onderbreken De analyses geven twee belanrijke pleisterplaatsen in

Marokko aan. Een in het westen de andere in het oosten van Marokko, de laaste is

van meer betekenis omdat daar meer individuen tijdens beide trekseisoenen zowel

voorjaars- als najaarsmigratie gebruik van maken. Gezenderde Grauwe

Kiekendieven pauzeren gemiddeld 9 dagen in Marokko tijdens de voor- en de

najaarstrek. Bij individuele vogels kon worden aangetoond dat zowel tijdens de

voorjaars- als de najaarsmigratie er plaatstrouw was aan pleisterplaatsen. Tijdens de

tweetal veldexpedities in Oost-Marokko in 2010 (april en september) hebben wij

geprobeerd gegevens over dichtheden, prooiaanbod en dieetkeuze van Grauwe

Kiekendieven te verzamelen. Hierbij werden systematische roofvogeltellingen vanaf

de weg uitgevoerd, het prooiaanbod geteld door transecten af te lopen en waar

mogelijk braakballen verzameld op slaapplaatsen. In het voorjaar hebben we 73

Grauwe Kiekendieven gezien, in het najaar 11. Op de gevondenen slaapplaatsen

zijn rond 10 Grauwe en 10 Bruine Kiekendieven waargenomen en braakballen

verzameld. Tijdens de wegtransecttellingen bedroeg het aantal roofvogels per 100

km transect 5,3, roofvogels. Het aantal Grauwe Kiekendieven bedroeg in het

voorjaar 0,2 en in het najaar 0,3 individuen per 100 km. Als je, een digitaale

landgebruik kaart gebruikend, de habitaten van de pleisteplaatsen van Grauwe

Kiekendieven met Marokko als referentie vergelijkt, dan lijken deze niet toevallig

gekozen te zijn. Bij analyse van de gegevens blijkt dat zowel tijdens de voorjaars- als

de najaarstrek het aandeel open gebieden significant te zijn oververtegenwoordigd in

de steekproef ten opzichte van de referentiegebieden In het oostelijke gebied was in

het voor- en najaar de landgebruik categorie 'kaale gebieden' oververtegenwoordigd

in vergelijk met het referentie gebied. In het westelijke voorjaars gebied waren

landgebruik categorieen, die agrarische gebieden betekenen, oververtegenwoordigd

in vergelijk met het referentie gebied. Maar als je dus de habitaten, die wij tijdens de

prooitransect tellingen noteerden, met de landgebruik categorien vergelijkd, is te zien

69

dat deze niet altijd juist zijn. 'Kaale gebieden' bijvoorbeeld zijn in het veld in Oost-

Marokko meestal steppe vegetatie of agrarische gebieden. Tijdens de

prooiaanbodtellingen bleek echter al snel dat de categorieën die worden gebruikt op

de satellietkaarten op onderdelen afweken van wat wij in het veld zagen. 'Open

gebieden' zijn in Oost-Marokko doorgaans gebieden met een karakteristieke

steppevegetatie of agrarisch gebied. In april bleken dus steppes en agrarische

gebieden met een zekere mate van akkerbouw te worden geprefereerd in

vergelijking tot de referentiegebieden. De Grauwe Kiekendieven, die we

observeerden, hadden een voorkeur voor agrarische gebieden als slaapplaatsen.

Tijdens de dag, hadden de kiekendieven een voorkeur voor agrarische gebieden en

verschillende typen steppe, dit representeerd waarschijnlijk foeragergebieden. De

steppegebieden zijn hoogstwaarschijnlijk preferent als foerageergebied Grauwe

Kiekendieven hadden een voorkeur voor gebieden die niet gedegradeerd waren. De

beschikbaarheid van potentiele prooi vogels was het hoogst in regios op de hogere

plateaus. Dit zijn ook tevens de gebieden die door de gezenderde Grauwe

Kiekendieven tijdens de rust als slaapplaats gebruikt worden. De prooisoort die in

beiden seisoenen met de hoogste aantallen te vinden was, is de Kortteenleeuwerik.

In het voorjaar worden meer potentieele prooi vogels getellt dan in het najaar.

Tijdens de voorjaarsrust lijken broedvogels, hun eieren en hun jongen als prooi

belangrijk te zijn. Dit bleek uit de verzamelde dieetgegevens. In april 2010 bleken

achtereenvolgens zangvogeleieren, nestjonge zangvogels, kleine zoogdieren en

tenslotte reptielen te worden geconsumeerd. In het voorjaar werd het hoogste

aandeel potentiële vogelprooien per km transect in agrarische gebieden en

depressies vastgesteld. De aantallen waren ook hoog in de verschillende typen

steppen habitatens met meer dan 20 vogels per km. In de herfst zijn de hoogste

aantallen zangvogels per km transect ook in agrarische gebieden en in Artemisia

steppe vastgesteld. Bovendien hebben we in het najaar grote groepen van

Kalanderleeuweriken en Korteenleeuweriken waargenomen. De dichtheden van

potentiële prooivogels bleek lager in h habitattypen die meer gedegradeert waren.

Gezenderde Grauwe Kiekendieven hadden een voorkeur voor agrarische

gebieden en steppen habitaten om te foerageren en kozen daarvoor habitaten waar

meer potentiële prooi vogels zaten. Zij vermeden ook erg gedegradeerde

landschappen als gevolg van het lagere prooiaanbod. Uit de resultaten van dit

onderzoek blijkt de combinatie van satellietzenderdata in combinatie met metingen in

70

het veld tot interessante conclusies te leiden. Uit de satellietdata bleek al dat Oost-

Marokko van grote betekenis was voor Grauwe Kiekendieven uit NW-Europa. Door

de expedities in april en september weten we nu ook dat niet gedegradeerde

agrarische en steppegebieden met hoge dichtheden aan leeuweriken worden

geprefereerd. Behoud van deze gebieden is dus van betekenis voor een trekvogel

als de Grauwe Kiekendief.

71

8. Acknowledgements

Field work was carried out together with Christiane Trierweiler, Ben Koks and Rob

Buiter in spring 2010. Data was collected together with CT, BK and Hans Hut in

autumn 2010. For great support with the analyses and revision of the text, I warmly

thank CT. Thanks to Arne Hegemann for help with statistical analyses and all

persons reviewing former versions of the text. Jesús García helped us with his

advice. The Institute of Avian Research “Vogelwarte Helgoland” provided me with a

working environment in Wilhelmshaven throughout the analyses. I am grateful to the

Dutch Montagu´s Harrier Foundation that supported and taught me during the field

season. The project was financially possible due to support of the Deutsche

Wildtierstiftung (grant to CT), the DAAD (grant to AS), the Dutch Montagu’s Harrier

Foundation (who provided the satellite telemetry data and funding for fieldwork), the

Schure-Beijerink Popping Fonds and the Dr. J.L. Dobberke Stichting (both providing

funding for fieldwork). The work in Morocco was kindly facilitated by the local

counterparts Dr. Hamid Rguibi (University of El Jadida) and Khalid Bedhiaf

(president of the East-Moroccan Bird Ligue). The Ministry of Eaux & Forêts provided

a license to carry out scientific work in Morocco. The local forestries of Eaux &

Forêts and the local police stations provided support in the field. We are very grateful

for the great hospitality of the members of the East-Moroccan Bird Ligue.

72

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77

10. Appendix

Appendix 1: PTT ID, name, catching place, country, location and date, age and sex of 20 satellite tracked Montagu´s Harriers, of which data was

used in the analyses sorted by catching date. Catching location is given in decimal degrees. Age is at catching time. Exact age was known for

nestlings and birds ringed as nestlings. Females with brown iris coloration were aged as being approximately 3-4 K (calendar year). Sex “f” =

female, “m” = male.

catching location PTT ID name place country N E catching date age sex

67278 Rudi E-Groningen NL 53.21 7.1 15-Jul-06 adult m

41249 Cathryn E-Groningen NL 53.15 6.95 15-Jul-06 adult f

67277 Franz E-Groningen NL 53.11 7.13 20-Jul-06 6K m

66841 Merel N-Groningen NL 53.41 6.45 24-Jul-06 adult f

67275 Freyr Leer D 53.17 7.21 28-Jul-06 adult m

41434 Jinthe Flevoland NL 52.38 5.33 3-Jul-07 7K f

41170 Sigrid Flevoland NL 52.38 5.33 14-Jul-07 1K f

41325 Doris Soest D 51.62 8.44 17-Jul-07 adult f

41303 Margret Soest D 51.63 8.44 21-Jul-07 14K f

41202 Edzard E-Groningen NL 53.22 6.91 1-Aug-07 4K m

41311 Fenna E-Groningen NL 53.22 6.91 1-Aug-07 adult (3-4 K?) f

66842 Tania Hrodna BY 53.31 23.93 13-Jul-08 adult (3-4 K?) f

84627 Jurek Siedlce PL 52.1 22.85 16-Jul-08 1K m

84629 Jochen Cuxhaven D 53.79 8.56 26-Jul-08 3K m

94497 Remt N-Groningen NL 53.41 6.45 13-Jul-09 adult m

84625 Iben Ballum DK 55.09 8.67 18-Jul-09 2K f

94494 Mathilde Ballum DK 55.09 8.67 18-Jul-09 adult f

94496 Michael Ballum DK 55.09 8.67 18-Jul-09 adult m

94495 Sabine Emden D 53.46 7.05 4-Aug-09 adult (3-4 K?) f

55472 Klaus-Dieter Brandenburg D 52.55 14.05 5-Jul-10 adult m

77

78

Appendix 2: Standardized forms used for road transect counts.

observer(s): weather: clear / dust, visibility up to ..…km distant remarks:

date: 2010 which GPS used:

place: country: Morocco

degradation: 0 - no, 1 - few, 2 - much, 3 - complet ely

F=farmland, N=natural steppe, NA=natural steppe art emisia, NH=natural steppe halfa, D=depression, R=ro cks, T=trees, AE=anti-errosion, S=sand, V=village

start/stop Time

km

trees /ha

shrubs/ha

% grass/herbs

% crop

% stone

% sand

habitat type

degra-dation

GPS wpt

N E wpt no. species n age sex distance

: 0

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

:

78

79

Appendix 3: Standardized forms used for prey transect counts.

name(s) observer(s): % area grass/herbs height grass/herbs (cm)

date: 2010 % area crop heigth of crop (cm) place: Morocco % area stones no. trees per hectare weather: % area sand height of trees (m):

GPS wpt start: N E waypoint no. (start, end) , no. shrubs per hectare

GPS wpt stop: N E GPS used: height of shrubs (m):

starting time:

habitat type: end time:

degradation: 0 - no, 1 - few, 2 - much, 3 - completely degradation:

Species birds: bound to transect flying over Species others: N Plant species:

Passerine spec locust small (<3 cm) Halfa grass

Lark spec. locust medium (3-7 cm) Artemisia

Temminck´s Lark locust large (>7 cm) Noaea

Short-toed Lark active mammal holes: small (<=3 cm diam.) Fredolia

Lesser Short-toed Lark active mammal holes: medium (3-10 cm diam.) Salicornia

Lesser / Short-toed Lark active mammal holes: large (>10 cm diam.) Anabasis

Calandra Lark reptiles thistle

Thekla Lark beetles small (<=1 cm) wheat

Crested Lark beetles medium (1-2 cm) barley

Thekla/Crested Lark beetles large (>2 cm) grass

Hoopoe Lark cricket AE: anti-erosion

Common Swift butterfly D: depression

Barn Swallow F: farmland

Wheatear spec. N: natural steppe

Northern Wheatear NA: steppe artemisia

Desert Wheatear NH: steppe halfa

Red-rumped Wheatear R: rocks

S: sand

T: woodland

V: village

79

80

Appendix 4: Egg measurements of 12 lark species. Length and width (mm) derived

from Harrison & Castell (2004). Weight (g) estimated according to Hoyt (1978),

details see text.

species length breadth weight Skylark (Alauda arvensis) 23.8 17.1 3.7 Crested Lark (Galerida cristata) 22.7 16.8 3.4 Thekla Lark (Galerida theklae) 22.7 16.8 3.4 Short-toed Lark (Calandrella brachydactyla) 19.6 14.6 2.2 Lesser Short-toed Lark (Calandrella rufescens) 20 14.8 2.3 Bar-tailed Lark (Ammomanes cinctura) 21 15.3 2.6 Desert Lark (Ammomanes deserti) 23.3 16.5 3.4 Dupont Lark (Chersophilus duponti) 23 18.4 4.2 Calandra Lark (Melanocorypha calandra) 24.2 17.8 4.1 Thick-billed Lark (Ramphocoris clotbey) 25.7 18.5 4.7 Temminck´s Lark (Eremophila bilopha) 23.2 16.5 3.4 Hoopoe Lark (Alaemon alaudipes) 22.3 17.3 3.6

mean 22.6 16.7 3.4

81

Appendix 5: List of all bird species observed during field trips in Morocco in spring (9 - 22 April) and autumn (9 - 21 September) 2010. Given are

scientific, English, German and Dutch names. Species are ordered taxonomically according to Svensson et al. (2009). In the columns spring and

autumn is indicated if the species was seen during the field trip in this season.

Scientific name English name German name Dutch name spring autumn 1 Tadorna ferruginea Ruddy Shelduck Rostgans Casarca yes yes 2 Coturnix coturnix Quail Wachtel Kwartel yes no 3 Calonectris diomeda Cory´s Shearwater Gelbschnabel-Sturmtaucher Scopoli´s Pijlstormvogel yes no 4 Nycticorax nycticorax Black-crowned Night-

Heron Nachtreiher Kwak yes no

5 Bubulcus ibis Cattle Egret Kuhreiher Koereiger yes yes 6 Egretta garzetta Little Egret Seidenreiher Kleine Silverreiger yes yes 7 Ardea cinerea Grey Heron Fischreiher Blauwe Reiger no yes 8 Ciconia ciconia White Stork Weißstorch Ooievaar yes yes 9 Phoenicopterus ruber Flamingo Rosaflamingo Flamingo no yes 10 Gyps fulvus Griffon Vulture Gänsegeier Vale Gier yes no 11 Pandion haliaetus Osprey Fischadler Visarend no yes 12 Aquila chrysaetos Golden Eagle Steinadler Steenarend yes yes 13 Circaetus gallicus Short-toed Eagle Schlangenadler Slangenarend yes yes 14 Hieraaetus pennatus Booted Eagle Zwergadler Dwergarend yes yes 15 Milvus milvus Black Kite Schwarzmilan Zwarte Wouw yes yes 16 Circus aeruginosus Marsh Harrier Rohrweihe Bruine Kiekendief yes yes 17 Circus pygargus Montagu´s Harrier Wiesenweihe Grauwe Kiekendief yes yes 18 Buteo rufinus Long-legged Buzzard Adlerbussard Arendbuizerd yes yes 19 Accipiter nisus Sparrowhawk Sperber Sperwer no yes 20 Falco tinnunculus Kestrel Turmfalke Torenvalk yes yes 21 Falco naumanni Lesser Kestrel Rötelfalke Kleine Torenvalk yes yes 22 Falco subbuteo Hobby Baumfalke Boomvalk no yes

81

82

23 Falco biarmicus Lanner Falcon Lannerfalke Lannervalk yes yes 24 Alectoris barbara Barbary Partidge Felsenhuhn Barbarijse Patrijs no yes 25 Fulica atra Coot Blässhuhn Meerkoet no yes 26 Chlamydotis undulata Houbara Bustard Kragentrappe Westelijke Kraagtrap yes yes 27 Haematopus ostralegus Oystercatcher Austernfischer Scholekster no yes 28 Recurvirostra avosetta Avocet Säbelschnäbler Kluut yes yes 29 Himantopus himantopus Black-winged Stilt Stelzenläufer Steltkluut yes yes 30 Burhinus oedicnemus Stone Curlew Triel Griel yes yes 31 Cursorius cursor Cream-coloured

Courser Rennvogel Renvogel yes yes

32 Charadrius dubius Little Ringed Plover Flussregenpfeifer Kleine Plevier yes yes 33 Charadrius alexandrinus Kentish Plover Seeregenpfeifer Strandplevier yes no 34 Calidris alba Sanderling Sanderling Drieteenstrandloper no yes 35 Tringa ochropus Green Sandpiper Waldwasserläufer Witgat no yes 36 Actitis hypoleucos Common Sandpiper Flussuferläufer Oeverloper yes no 37 Tringa nebularia Greenshank Grünschenkel Groenpootruiter no yes 38 Numenius phaeopus Whimbrel Regenbrachvogel Regenwulp no yes 39 Chroicocephalus

brunnicephalus Black-headed gull Lachmöwe Kokmeeuw no yes

40 Larus michahellis Yellow-legged Gull Mittelmeermöwe Geelpootmeeuw yes yes 41 Larus audouinii Audouin´s Gull Korallenmöwe Audouins Meeuw yes yes 42 Chlidonias niger Black Tern Trauerseeschwalbe Zwarte Stern no yes 43 Pterocles orientalis Black-bellied

Sandgrouse Sandflughuhn Zwartbuikzandhoen yes yes

44 Pterocles alchata Pin-tailed Sandgrouse Spießflughuhn Witbuikzandhoen yes yes 45 Pterocles coronatus Crowned Sandgrouse Kronenflughuhn Kroonzandhoen yes no 46 Coluba livia Rock Dove Felsentaube Rotsduif yes yes 47 Coluba livia f. domestica Feral Pigeon Straßentaube Stadsduif yes yes

82

83

48 Columba palumbus Wood Pigeon Ringeltaube Houtduif no yes 49 Streptopelia decaocto Collared Dove Türkentaube Turkse Tortel yes yes 50 Streptopelia turtur Turtle Dove Turteltaube Zomertortel yes yes 51 Cuculus canorus Common Cuckoo Kuckuck Koekoek yes no 52 Asio flammeus Short-eared Owl Sumpfohreule Velduil yes no 53 Athene noctua Little Owl Steinkauz Steenuil yes yes 54 Bubo ascalaphus Pharao Eagle Owl Nordafrikanischer Uhu Noordafrikaanse Oehoe no yes 55 Apus apus Common Swift Mauersegler Gierzwaluw yes yes 56 Upupa epops Hoopoe Wiedehopf Hop yes yes 57 Alcedo atthis Kingfisher Eisvogel Ijsvogel yes no 58 Merops apiaster European Bee-eater Bienenfresser Bijeneter yes yes 59 Coracias garrulus Roller Blauracke Scharrelaar yes no 60 Alauda arvensis Skylark Feldlerche Veldleeuwerik yes no 61 Galerida cristata Crested Lark Haubenlerche Kuifleeuwerik yes yes 62 Galerida theklae Thekla Lark Theklalerche Theklaleeuwerik yes yes 63 Calandrella brachydactyla Short-toed Lark Kurzzehenlerche Kortteenleeuwerik yes yes 64 Calandrella rufescens Lesser Short-toed Lark Stummellerche Kleine

Kortteenleeuwerik yes yes

65 Ammomanes deserti Desert Lark Steinlerche Woestijnleeuwerik no yes 66 Ammomanes cinctura Bar-tailed Lark Sandlerche Rosse

Woestijnleeuwerik no yes

67 Melanocorypha calandra Calandra Lark Kalanderlerche Kalanderleeuwerik yes yes 68 Rhamphocoris clotbey Thick-billed Lark Knackerlerche Diksnavelleeuwerik yes yes 69 Emerophila bilopha Temminck´s Lark Saharaohrenlerche Temmincks

Strandleeuwerik yes yes

70 Chersophilus duponti Dupont´s Lark Dupontlerche Duponts Leeuwerik yes yes 71 Alaemon alaudipes Hoopoe Lark Wüstenläuferlerche Witbandleeuwerik yes yes 72 Riparia riparia Sand Martin Uferschwalbe Oeverzwaluw yes yes

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73 Riparia paludicola Brown-throated Martin Braunkehlschwalbe Vale Oeverzwaluw yes no 74 Ptynoprogne rupestris Crag Martin Felsenschwalbe Rotszwaluw yes no 75 Hirundo rustica Barn Swallow Rauchschwalbe Boerenzwaluw yes yes 76 Delichon urbicum House Martin Mehlschwalbe Huiszwaluw yes no 77 Anthus campestris Tawny Pipit Brachpieper Duinpieper yes no 78 Anthus cervinus Red-throated Pipit Rotkehlpieper Roodkeelpieper yes no 79 Motacilla flava Yellow Wagtail Schafstelze Gele Kwikstaart yes yes 80 Lusicina megarhynchos Nightingale Nachtigall Nachtegaal yes no 81 Phoenicurus phoenicurus Redstart Gartenrotschwanz Gekraagde Roodstaart yes no 82 Oenanthe oenanthe Northern Wheatear Steinschmätzer Tapuit yes yes 83 Oenanthe seebohmi Seebohm´s Wheatear Nordafrikanischer

Steinschmätzer Noordafrikaanse Tapuit yes yes

84 Oenanthe leucopyga White-crowned Wheatear

Saharasteinschmätzer Witkruintapuit yes yes

85 Oenanthe leucura Black Wheatear Trauersteinschmätzer Zwarte Tapuit yes yes 86 Oenanthe deserti Desert Wheatear Wüstensteinschmätzer Woestijntapuit yes yes 87 Oenanthe moesta Red-rumped Wheatear Fahlbürzel-Steinschmätzer Roodstuittapuit yes yes 88 Saxicola rubetra Whinchat Braunkehlchen Paapje yes no 89 Turdus merula Blackbird Amsel Merel yes yes 90 Sylvia atricapilla Blackcap Mönchsgrasmücke Zwartkop yes no 91 Sylvia communis Whitethroat Dorngrasmücke Grasmus yes no 92 Sylvia melanocephala Sardinian Warbler Samtkopfgrasmücke Kleine Zwartkop yes yes 93 Sylvia conspicallata Spectacled Warbler Brillengrasmücke Brilgrasmus yes no 94 Sylvia cantillans Subalpine Warbler Weißbartgrasmücke Baardgrasmus yes no 95 Scotocerca inquieta Scrub Warbler Wüstenprinie Maquiszanger no yes 96 Cisticola juncidis Zitting Cisticola Cistensänger Graszanger yes no 97 Hippolais polyglotta Melodious Warbler Orpheusspötter Orpheusspotvogel yes no 98 Hippolais pallida Olivaceous Warbler Blaßspötter Vale Spotvogel yes no

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99 Phylloscopus trochilus Willow Warbler Fitis Fitis yes no 100 Phylloscopus sybilatrix Wood Warbler Waldlaubsänger Fluiter yes no 101 Regulus ignicapillus Firecrest Sommergoldhähnchen Vuurgoudhaan yes no 102 Troglodytes troglodytes Wren Zaunkönig Winterkoning yes no 103 Pycnonotus barbatus Common Bulbul Graubülbül Grauwe Buulbuul no yes 104 Cercotrichas galactotes Rufous Bush Robin Heckensänger Rosse Waaierstaart no yes 105 Muscicapa striata Spotted Flycatcher Grauschnäpper Grauwe Vliegenvanger yes yes 106 Ficedula hypoleuca Pied Flycatcher Trauerschnäpper Bonte Vliegenvanger yes no 107 Parus major Great Tit Kohlmeise Koolmees yes no 108 Lanius excubitor Great Grey Shrike Raubwürger Klapekster yes yes 109 Lanius senator Woodchat Shrike Rotkopfwürger Roodkopklauwier yes no 110 Turdoides fulva Fulvous Babbler Akaziendrossling Bruingele Babbelaar no yes 111 Pica pica Magpie Elster Ekster yes no 112 Garrulus glandarius Jay Eichelhäher Gaai yes no 113 Corvus corax Common Raven Kolkrabe Raaf yes yes 114 Corvus ruficollis Brown-necked Raven Wüstenrabe Bruinnekraaf yes yes 115 Passer domesticus House Sparrow Haussperling Huismus yes yes 116 Passer hispaniolensis Spanish Sparrow Weidensperling Spaanse Mus yes yes 117 Fringilla coelebs Chaffinch Buchfink Vink yes yes 118 Carduelis carduelis Goldfinch Stieglitz Putter yes yes 119 Carduelis chloris Greenfinch Grünfink Groenling yes yes 120 Serinus serinus Serin Girlitz Europase Kanarie yes no 121 Bucanetes githagineus Trumpeter Finch Wüstenfink Woestijnvink yes yes 122 Miliaria calandra Corn Bunting Grauammer Grauwe Gors yes no 123 Emberiza cia Rock Bunting Zippammer Grijze Gors yes no

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Hiermit versichere ich, dass ich diese Arbeit selbstständig verfasst und keine anderen als die angegebenen Quellen und Hilfsmittel benutzt habe. Außerdem versichere ich, dass ich die allgemeinen Prinzipien wissenschaftlicher Arbeit und Veröffentlichung, wie sie in den Leitlinien guter wissenschaftlicher Praxis der Carl von Ossietzky Universität Oldenburg festgelegt sind, befolgt habe. Oldenburg, 28 March 2011