Biodiversity Concepts and Urban Ecosystems

Biodiversity concepts and urban ecosystems

Jean-Pierre L. Savarda,*, Philippe Clergeaub, Gwenaelle Mennechezb

aCanadian Wildlife Service, 1141 Route de l'EÂ glise, P.O. Box 10100, Sainte-Foy (QueÂ.), Canada G1V 4H5bINRA FAUNE SAUVAGE and UMR CNRS Ecobio, Avenue du GeÂneÂral Leclerc, 35042 Rennes cedex, France

Received 10 January 1998; accepted 20 September 1999

Abstract

The association of biodiversity and urban ecosystems has usually concerned the impact of urbanization on biodiversity.

However, biodiversity concepts can easily be applied to the urban ecosystem itself. As more and more people live in cities,

restoration, preservation and enhancement of biodiversity in urban areas become important. Concepts related to biodiversity

management such as scale, hierarchy, species identity, species values, fragmentation, global approaches can be used to manage

urban biodiversity. Application of these concepts in such arti®cial ecosystems may yield important insights for the

management of natural ecosystems. Birds are highly visible and quite sensitive to changes in habitat structure and

composition. Bird species richness in urban ecosystems is in¯uenced both by local and landscape characteristics and a multi-

scale approach is essential to its proper management. People±wildlife con¯icts are an integral component of wildlife

management in urban ecosystems and must be addressed. Enhancement of biodiversity in urban ecosystems can have a

positive impact on the quality of life and education of urban dwellers and thus facilitate the preservation of biodiversity in

natural ecosystems. # 2000 Elsevier Science B.V. All rights reserved.

Keywords: Biodiversity concepts; Urban ecosystems; Birds in cities

1. Introduction

In the last decade, biodiversity concerns have been

in the forefront of conservation efforts worldwide

(Environment Canada, 1994; UNEP, 1995). Biodiver-

sity has been de®ned in various ways (McNeely et al.,

1990; Salwasser, 1990) but the term has generally

been used in a very comprehensive manner meaning

the variability of life (composition, structure and

function). Biodiversity can be represented as an inter-

locked hierarchy of elements on several levels of

biological organization (Noss, 1992). Since the term

`biodiversity' transcends all levels of life from genes

to communities and all spatial and temporal scales

(Noss, 1990; Savard, 1994), it has generated a lot

of confusion and misunderstanding (West, 1993;

Lautenschlager, 1997). However, when understood

and used properly biodiversity concepts can provide

a useful framework for conservation efforts (Savard,

1994).

Urban ecosystems have usually been examined in

terms of their impact on biodiversity (Middleton,

1994; Wackernagel and Rees, 1996). However, while

the impact of a city on adjacent ecosystems can be

signi®cant (Douglas, 1983), much can be learned by

applying biodiversity concepts to the urban ecosystem

Landscape and Urban Planning 48 (2000) 131±142

* Corresponding author.

0169-2046/00/$20.00 # 2000 Elsevier Science B.V. All rights reserved.

PII: S 0 1 6 9 - 2 0 4 6 ( 0 0 ) 0 0 0 3 7 - 2

itself. Enhancement of biodiversity in urban ecosys-

tems can be quite important as some evidences suggest

that personal exposure to natural things in everyday

life is a major determinant of sensitivity to environ-

mental issues (Sebba, 1991; Rohde and Kendle, 1994).

As the proportion of urban residents increases every

year worldwide, the nature of urban ecosystems would

become increasingly important in shaping people's

views about natural ecosystems. Also, from an eco-

logical perspective, urban ecosystems are highly

dynamic (Gilbert, 1989; Adams, 1994) and can pro-

vide useful insights into the management of biodiver-

sity in other ecosystems. They are characterized by a

high level of heterogeneity often organized along

gradients extending from the surrounding landscape

to the town centre (McDonnell and Pickett, 1990;

McDonnell et al., 1993).

Biodiversity concerns related to urban ecosystems

can be divided into three major groups: (1) those

related to the impact of the city itself on adjacent

ecosystems; (2) those dealing with how to maximize

biodiversity within the urban ecosystem and (3) those

related to the management of undesirable species

within the ecosystem. While species diversity and

abundance are often related to the quality of urban

life (Adams, 1994; Middleton, 1994) the overabun-

dance of some species can be at times undesirable

(Cooper, 1987; Clergeau et al., 1996).

This paper deals with concerns related to the urban

ecosystem itself using birds as a target group. Birds are

quite sensitive to changes in habitat structure and

composition and are therefore excellent indicators

of changes and stresses in the urban ecosystem

(Savard and Falls, 1982; Clergeau et al., 1998). We

start by reviewing some important concepts related to

biodiversity preservation. We then review the impor-

tance of local and landscape attributes in in¯uencing

the abundance, diversity and distribution of birds in

urban ecosystems and ®nally, we identify approaches

and activities than can enhance urban bird diversity.

2. Important concepts related to biodiversity

2.1. Hierarchy of scales

Life is structured in a hierarchical fashion starting

with cells forming individuals, which regroup into

populations, which in turn form species, who end up as

communities. Biodiversity concerns can occur at any

level of organization. Levels of biological organiza-

tion often correspond to speci®c spatial and temporal

scales and must be addressed at their appropriate

scale. Some concerns may focus on managing a

population of geese in an urban park, others on

increasing the number of bird species in the entire

city. It is important when dealing with a concept as

general as biodiversity to identify at which organiza-

tional level we want to act, or which group of organ-

isms we target. In this case, we con®ne ourselves to

birds but the same argument could be applied to

plants, insects or mammals. In fact, biodiversity

includes all forms of life.

As biodiversity is expressed in a multitude of spatial

scales, it is essential to specify the scale(s) of interest

when using the term biodiversity (Savard, 1994).

Failure to do so will quickly generate confusion and

misunderstanding, since it is frequent to ®nd different

and even contradictory results on different scales

(Wiens, 1989). A multi-scale approach is thus neces-

sary to properly address biodiversity questions. Scales

are not independent from one another but linked in a

hierarchical way (Allen and Starr, 1982) so the effects

of an action at a given scale must be considered on

higher and lower scales (Savard, 1994). Within urban

ecosystems, actions taken to preserve or enhance

biodiversity should be so at scales ranging from

individual plants to the entire city itself and even its

surrounding areas (Table 1). Temporal scales are also

important to consider. Bird abundance and diversity in

urban ecosystems vary with the seasons and even from

year to year (Savard, 1978). The use of an urban park

by birds varies according to the time of day causing

bird diversity and abundance to ¯uctuate throughout

the day. When discussing and studying bird diversity it

is also important to specify the type of diversity that

interests us. For example, a park may have only two

breeding species but be used for feeding by 10 species

during the summer and ®ve during the winter.

The hierarchical approach emphasizes logical and

functional linkages among scales. Because biodiver-

sity transcends several spatial and temporal scales as

well as several organizational levels (from genes to

communities), its management should be incorporated

into a hierarchical decision system (Rice, 1992) as in

some species management (Clergeau, 1995). In such a

132 J.-P.L. Savard et al. / Landscape and Urban Planning 48 (2000) 131±142

Table 1

Various actions related to increasing bird diversity and abundance in urban ecosystem in relation to spatial scales

Scale Management level Planning Design Management

Adjacent landscapes Regional Government

or equivalent

Zone landscape use; identify and

protect important natural areas

for birds; identify green corridors

linking the city to natural areas;

create regional parks.

Design parks and green corridors

to optimize their use by birds;

design roadways to minimize

fragmentation of natural areas,

Plant vegetation and restore habitats to

improve parks and corridors; promote

management options that favor bird

diversity

City Municipal Government Extend green corridors within the

city; identify important areas for

birds within the city; identify

important bird species.

Shape, structure and size up

corridors to optimize bird use;

design park to increase bird

abundance and diversity; design

Building to reduce bird collisions.

Reduce lighting of building at night during

migration periods; manage waste to mini

mize bird problems; plant vegetation in

parks, green corridors and along streets.

City sectors (industrial,

commercial, residential,

recreational)

Local authorities Establish vegetation objectives.

Interact with higher levels to insure

optimal location of natural areas, parks

and corridors; create management

plan for parks that will preserve and

enhance bird diversity.

Design type, structure and distribution

of vegetation to favor birds; insure

building architecture compatible

with birds.

Enhance or restore vegetation in industrial

and commercial areas; reduce use of

herbicides and pesticides; plantation of

shrubs, fruit trees, conifers; modify building

structures to avoid bird problems.

Individual lots Owner Landscape property to attract birds:

coordinate with neighbors to

maximize vegetation volume.

Select type of vegetation most

compatible with birds; design

nesting and feeding structures.

Install and maintain nest boxes and bird

feeders; avoid use of pesticides and herbi

cides; manage to reduce vulnerability of

birds to cats; retain safe snags.

J.-P.L

.S

ava

rdet

al./L

an

dsca

pe

an

dU

rban

Pla

nnin

g48

(2000)

131±142

133

system, higher levels constrain to various degrees the

actions taken at lower levels. In urban areas for

example, city regulations limit what individuals can

or cannot do. It is imperative to adopt a hierarchical

approach to properly manage biodiversity across

scales. Such an approach in¯uences local actions

whenever those actions have undesirable effects on

larger scales.

Constraints may include mandatory coordination

across scales and levels. For example, a grassland

park in a city may have only ®ve breeding bird species,

three of which are speci®c to that park. Local bird

diversity of the park could be doubled or tripled by

converting this grassland park into a wooded one.

However, this would result in the loss of three species

for the city as a whole. So, in this case, an increase in

local diversity would result in a decrease in diversity at

the scale of the city. Obviously, a choice has to be

made here, as to which scale we want to give priority

to. It doesn't necessarily have to be the greater scale as

long as efforts are coordinated across the scales. Since

urbanized areas already function within a hierarchical

decision system, it should be relatively easy to extend

to biodiversity management. In the example described

here, there could be a general policy on the scale of the

city to preserve and enhance the unique features of

some parks. Once those features are identi®ed and

protected, a general goal of increased species richness

can then be applied to all parks. Food webs and trophic

relationships illustrate well the hierarchical organiza-

tion of life and stress an other important point to

consider when managing biodiversity: all species

are not equal.

2.2. Species

One important aspect in dealing with biodiversity is

that not all species are equal. Species vary in size,

shape, abundance, distribution, trophic position, eco-

logical function, feeding habits and desirability.

Therefore, diversity indices which assume all species

as being equal are of little use for properly managing

biodiversity (Savard, 1994). Some species may play

important roles in the community, so their absence

would signi®cantly affect several other species. Iden-

ti®cation of these species is dif®cult since their role

may be seasonal or even habitat speci®c (Bond, 1993).

It is important to identify desirable species. For exam-

ple, in the context of an objective to increase bird±

people interactions, bird abundance would be more

important than bird diversity. Conspicuous species

would be preferred to furtive ones, as would species

yielding positive interactions.

Other species-related concepts used in biodiversity

conservation are the concept of umbrella species and

¯agship species (Hunter, 1990). Umbrella species are

at the top of food chains or with large home ranges so

that by protecting these species we protect all species

on which they depend or the species with similar

requirements but smaller home ranges. For example,

Merlin (Falco columbarius) could be considered as an

umbrella species in several North American cities as it

feeds on songbirds and nests in tall trees. An abun-

dance of small birds is therefore essential for the well

being of Merlin in urban areas. Because House Spar-

row (Passer domesticus) and European Starling (Stur-

nus vulgaris) often represent over 70% of the birds in

urban areas, they are crucial as a prey base for the

maintenance of some birds of prey in urban ecosys-

tems.

This concept is like the coarse ®lter approach

mentioned further. Flagship species are charismatic

species which attract attention and which can be used

to galvanize public support for conservation efforts. A

good example of a charismatic species is the Peregrine

Falcon (F. peregrinus) whose nesting in cities has

attracted considerable attention and greatly facilitated

conservation efforts (Cade and Bird, 1990). An other

example is the White Stork (Ciconia ciconia) in

Europe which nest on chimneys (Cramp et al.,

1977). Birds can also be excellent indicators of various

aspects of urban ecosystems (biodiversity; vegetation

structure; contaminants). In this respect, Rock Dove

(Columbea livia) has been used successfully to moni-

tor heavy metal contamination along urbanization

gradients (Drasch et al., 1987). In urban ecosystems

bird species also vary in terms of how they are

perceived by people (Brown et al., 1979; Penland,

1987). Some species such as European Starlings,

House Sparrow and Rock Doves are often appreciated

at low density but are sometimes perceived as a

nuisance at high densities. People±wildlife interac-

tions are crucial in urban ecosystems (Brown et al.,

1979) and any enhancement of biodiversity must take

them into consideration (Michelson, 1970; Gilbert,

1989; Clergeau et al., 1997).


2.3. Habitat fragmentation and habitat quality

Habitat fragmentation can be extreme within urban

ecosystems. Its effect occurs at all spatial scales and

affects all organisms. Fragments of natural vegetation

may be too small or even too isolated to support some

species. In a park, shrubs abundance and distribution

will in¯uence the presence and abundance of bird

species nesting in shrubs whereas park distribution,

size and abundance in a city will affect bird diversity.

Vegetation corridors linking urban green areas

between themselves and/or with rural habitats are

important to maintain and enhance urban biodiversity

(Flink and Searns, 1993). They facilitate movements

and ensure colonization of isolated natural areas

(Clergeau, 1998). Streams form natural corridors in

urban areas and should be managed as such. In

Toronto, natural ravines within the city have been

preserved and act as corridors between parks. Well-

vegetated residential areas constitute aerial corridors

through their tree canopy. Such corridors are espe-

cially useful for migrating birds which use them

extensively as they provide food and protection

against aerial predators (Savard, 1978). Greenways

act not only as movement corridors (Clergeau and

Burel, 1997) but can also provide breeding habitats for

several edge species (Noss, 1993).

Like for most ecosystems, our knowledge of urban

biodiversity and its distribution is limited especially to

small organisms. In view of that lack of knowledge a

coarse ®lter approach is indicated where we seek to

protect natural habitats within cities and by doing so

protect most of the species associated with that habi-

tat. For example, an increase in the volume and

diversity of vegetation in a city would increase bird

abundance and diversity and such an approach can be

applied to all spatial scales (Table 1). The coarse grain

approach does not protect all species and needs to be

complemented by a ®ner approach dealing with spe-

ci®c species (Hunter, 1990). This is most crucial in

urban ecosystems where habitats are most fragmented

and isolated. Protected fragments may lack some key

resources needed by species we would like to retain

(i.e. nest site, shelter, food, etc.).

These concepts are closely related to biodiversity

conservation (Savard, 1994) and can easily be applied

to urban ecosystems. Biodiversity concepts are quite

general and must be re®ned at manageable levels and

scales. Statements like òur goal is to enhance urban

biodiversity' are not workable because of the encom-

passing nature of the word biodiversity. Something

like òur goal is to increase bird diversity in urban

parks' is more appropriate as it speci®es the group of

organisms, as well as the scale of action. It is essential

to elaborate achievable goals. It is also important not

to confound biodiversity and species diversity as they

are quite different concepts. Species diversity is only a

small portion of biodiversity and deals mostly with

species richness, sometimes incorporating abundance

as well. Biodiversity includes all forms of life, as well

as structural and functional aspects.

3. Importance of local and landscape attributesfor bird abundance and biodiversity

Three species have adapted particularly well to

urban ecosystems and have colonized them world-

wide: the House Sparrow, the European Starling and

the Rock Dove. These species dominate the urban

avifauna of most cities and are usually quite dominant

in the most urbanized part of a city (Table 2). Although

often neglected by ornithologists, these species con-

stitute the core of urban avifauna and their role is quite

crucial, especially in the more densely populated

areas. Species richness tends to be higher in the more

vegetated areas and lowest in the downtown areas, and

this throughout all studies (Table 2).

New residential developments with little or no

original vegetation have a low diversity of birds,

but depending on the architectural structure of their

buildings, can sometimes support high densities of

birds. Bird diversity typically increases as vegetation

develops (Hohtola, 1978; Luniak, 1994). Urban wood-

lands are an important component of the urban land-

scape in terms of bird species diversity. The larger the

woodland, the more species it supports (Sasvari, 1984;

Tilghman, 1987a). For similar size woodlots, spatial

heterogeneity, complex vertical structure and diverse

species composition of vegetation are all associated

with higher bird species richness (Cavareski, 1976;

Tilghman, 1987b). Composition of the native compo-

nent of urban bird communities varies according to the

geographical location of the city (Table 2), its land-

scape context and the amount of natural vegetation

contained in the city.

J.-P.L. Savard et al. / Landscape and Urban Planning 48 (2000) 131±142 135

Urban ecosystems are quite similar worldwide in

terms of structure, functions and constraints. They

differ in terms of their geographical location, their

size and the type of landscape they modify. The

landscape surrounding a city greatly in¯uences plant

and wildlife species that will be found within the new

arti®cial ecosystem. It is essential to consider land-

scape factors in the management of urban biodiversity.

For example, a high breeding density of European

Starlings in a residential area can be due in part to the

presence of extensive lawn surface in neighboring

areas or parks where birds feed. Similarly, the pre-

sence of large numbers of gulls in a sector can be due

to the presence of nearby open water or of a breeding

colony in surrounding areas.

The reproductive success of birds often varies with

the type of habitat selected. We found such a pattern in

the reproductive parameters of European Starlings that

varied from low in the downtown area to high in peri-

urban sectors (Table 3). Thus, some sectors of the city

may act as a source of starlings while others may not

sustain viable populations. Such variation in repro-

Table 2

Proportion of introduced species (%) in breeding bird communities of urban areas in relation to level of urbanizationa

Location Downtown

area

Residential area Semi-natural

area

Reference

Vegetation rare Vegetation

abundant

Vegetation very

abundant

Toronto, Canada 94±98 (2)b 92±97 (5) 72±82 (6) 73 (1) 43±54 (2) Savard (1978)

[5±5]c [7±10] [7±15] [12] [21±22]

QueÂbec, Canada 68 (1) 73 (1) 27±52 (3) 34 (1) 48 (1) Clergeau et al. (1998)

[13] [19] [23±25] [31] [27]

Rennes, France 52 (1) ± 26±43 (3) 25 (1) 34 (1) Clergeau et al. (1998)

[10] ± [21±23] [26] [30]

Vancouver, Canada ± 76 (1) 57 (1) 23 (1) 34 (1) Weber (1972)

[10] [9] [16] [14]

Blacksburg, Virginia ± 97 (1) 52±57 (2) 31±39 (3) 9 (1) Lucid (1974)

[6] [14±17] [16±24] [21]

Washington DC ± 95 (1) 60 (1) ± 38 (1) Williamson (1974)

[±] [±] [±]

Warsarw, Poland ± 80±85 (4) ± ± 45±1 (l) Luniak (1994)

[9±16] [23]

Tornio, Finland ± 41 (1) 24 (1) 0 (1) Huhtalo and Jarvinen (1977)

[14] [27] [25]

Kuopio, Finland 66±79 (3) ± 12±34 (3) 8±48 (4) 0±33 (4) Hohtola (1978)

[3±5] [11±19] [8±18] [6±14]

a Introduced species include European Starling, House Sparrow and Rock Dove. Although not introduced in European cities they have

been regrouped there for comparison purposes.b Range of % of introduced species; (number of areas sampled).c [Number of species (range)].

Table 3

Reproductive parameters of European Starling in Rennes in relation to the urbanization gradient

Urban center Peripheric areas Countryside

Laying date 6 April�1 day 4 April�2 days 1st April�2 days

(n�7) (n�14) (n�12)

Clutch size 5.0�0.0 5.6�0.9 6.0�0.5

(n�6) (n�14) (n�10)

Number of eggs hatching 2.8�2.0 5.0�0.8 5.7�0.5

(n�6) (n�15) (n�10)


ductive success between urban habitats has been

reported for several species (Nuorteva, 1971; Smith

and Gilbert, 1984). The presence of urban populations

of starlings may play a role in attracting large roosting

populations of rural starlings. Understanding of

urban±rural movements and their cause is essential

to properly manage these populations (Clergeau,

1981).

The impact of urbanization on a given landscape is

partially a function of the original composition of the

landscape. Urbanization will increase bird diversity of

simple landscapes such as desertic areas or grassland

areas by creating new habitats and supporting exotic

species of birds (Emlen, 1974). In diversi®ed land-

scapes that support an initial high diversity of habitats,

a decrease in bird diversity is likely to occur as

urbanization becomes more prevalent, eliminating

unique natural habitats (Batten, 1972). Landscape

factors such as the composition and arrangement of

habitat types around a local area have signi®cant

impacts on bird populations of that local area and

must be taken into account when managing the local

area (i.e. a park, a residential area, etc.). Landscape

context is especially important in complex landscapes

such as found in urban ecosystems (Dunning et al.,

1992).

4. Approaches to enhance urban biodiversity

There is no single best starting point when dealing

with biodiversity. Local actions as well as regional

actions are equally important on their respective scale.

In urban areas home-owners can take various actions

on the scale of their lot. It is important to realize that it

is the concerted efforts at various scales that produce

the best results. It is essential that home-owners realise

that their own local action can contribute to a larger

collective effort that would culminate in the creation

of a real biological corridor that facilitates the move-

ments of several species throughout the city. Such

collective efforts proved quite powerful in Belgium

(Laurence and Palmaerts, 1991). Urban planners can

act on a larger scale, either in neighborhoods or in the

entire city. Urban growth must now take into con-

sideration the creation of large recreational zones

which often, upon request of citizens, must remain

as natural as possible. These zones must integrate

social and ecological considerations to avoid con¯icts.

The overall thinking about green spaces, corridors,

wildlife and people is common to all cities but solu-

tions vary greatly depending on local, physical, social

and ecological constraints. Whatever the scale of

intervention, one important aspect is to evaluate the

impact of a given action on smaller and larger scales in

order to avoid unwanted results.

A ®rst approach for urban planners would be to

inventory resources within the city (natural area, lake,

river. . .) and their organization (unique structures,

corridors) and to assess the abundance, distribution

and possible concerns about these resources. Once

resources have been identi®ed on the scale of the city

itself, strategies can be established for preserving and

using them whenever necessary. Such strategies

should account for local constraints and assets. Local

actions will develop around those constraints or

opportunities and address speci®c objectives. For

example, trees may be planted in a residential area

to increase vegetation volume and thus increase insect

and bird diversity. In some countries where the

weather is harsh, bird feeders may be encouraged

or even maintained in parks to enhance local diversity.

Similarly, nest boxes may be erected for particular

species, etc. Another important aspect to consider is

the landscape context. This is important, as the main-

tenance of some resources within the city may depend

on what is happening outside the city. For example, a

stream originating outside the city will be affected by

neighboring areas, or an urban park, by neighboring

residential areas. Table 4 lists a multi-scale approach

that re¯ects the considerations given earlier.

Some activities to enhance urban bird diversity are

worth mentioning here:

4.1. Plantation of trees and shrubs

Bird diversity in urban areas tends to be propor-

tional to the existing volume of vegetation (Emlen,

1974; Lancaster and Rees, 1979). During migration,

numbers and diversity of migrating birds within the

city are also proportional to vegetation abundance

(Savard, 1978). Tree species selection is also impor-

tant. Conifer trees provide nesting cover for several

species of birds and are heavily used for cover in

winter (Savard, 1978). Fruit trees attract frugivorous

birds, especially in winter. For example, in some


Canadian cities, plantation of Mountain Ash (Sorbus

americana) along city streets have attracted large

numbers of wintering Bohemian Waxwings (Bomby-

cilla garrulus) which in turn provided food for winter-

ing Merlin which increased in numbers within the city

(Oliphant and Haug, 1985). Several bird species nest

and forage in shrubs so that addition of shrub thickets

to an area would increase bird species diversity.

4.2. Provision of arti®cial nesting structures

Several bird species frequenting urban ecosystems

are cavity or cliff nesters and are often limited by

availability of nesting structures. Reproductive suc-

cess and breeding densities of several of these species

are sometimes greater in urban ecosystems than in

their natural habitats (Smith and Gilbert, 1984). Arti-

®cial chimneys have been used to attract nesting swifts

(Apus sp.) and Peregrine Falcons have successfully

nested on arti®cial structures in cities (Cade and Bird,

1990). Architectural design of buildings can provide

nesting sites for House Sparrow, Starlings and Rock

Dove, which is not always a desirable thing. Careful

design of buildings may avoid costly problems.

4.3. Provision of bird feeders

Bird feeders are quite ef®cient in increasing local

bird diversity especially in winter. Species' attraction

depends on the type of food found in feeders, their

location and the type of surrounding habitat. However,

feeding of birds may attract undesirable species or

concentrate too many birds into a small area. Whereas

feeding of small seed eating birds is generally a

positive activity, feeding of large birds in parks or

other urban areas often results in negative impacts on

the habitat and/or generates people±wildlife con¯icts.

4.4. Regulating human behavior

Urban problems related to birds are usually due in

part to human behavior. For example, improper sto-

rage of human waste may attract large numbers of

scavenging birds. Architectural features of buildings

often encourage nesting of undesirable species. Free

roaming by cats and dogs is an important source of

disturbance and predation on birds. Some Canadian

cities have regulations restricting free roaming of cats

and dogs which greatly reduces their impact on wild-

life.

4.5. Creation, restoration and management of

natural areas

Parks or other green spaces within urban areas can

act as a source of birds for neighboring residential

areas. Bird diversity observed in backyards would

likely be higher in properties adjacent to a natural

area. Size and shape of green areas are important in

determining the number of species they attract. These

patches of natural habitats can greatly enhance local

bird diversity (Cavareski, 1976; Tilghman, 1987a, b).

Riparian areas along streams provide important corri-

dors for wildlife in urban areas. Preservation of the

Table 4

A multi-scale approach: to enhance bird abundance and diversity in the city we may want to

1. Examine the country side surrounding the city and secure or restore important bird habitats that may act as a source of birds for the city;

establish a greenbelt around the city.

2. Identify and consolidate vegetation corridors linking these areas to the city and link parks whenever possible; make use of natural

streams and right of ways.

3. Increase the volume and diversity of vegetation in the city (along streets, right of ways, industrial, commercial and residential sectors).

4. Exploit and enhance the features of some parks that may attract particular species of birds.

5. Increase the structural diversity of vegetation in natural and recreational parks of the city.

6. Plant conifers and fruit trees to provide cover and food for birds; promote the night blackout of tall buildings during bird migration and

encourage architecture that minimizes bird collisions.

7. Erect special nesting structure for cavity or cliff nesting species (nest boxes for owls, chimneys for swifts, nesting platforms for falcons

or storks).

8. Encourage homeowners to manage their property for birds, to restrain their pets and to minimize the use of pesticides and herbicides.

9. Distribute guidelines as to the proper planting of trees and shrubs to attract birds.

10. Maintain bird feeders, nest boxes, bird baths in backyards.


vegetative integrity of these natural greenways can

signi®cantly enhance urban biodiversity. Degraded

urban habitats can be restored and contribute to local

biodiversity, as well as to the development of restora-

tion techniques for natural ecosystems (Berger, 1988).

5. Management of people±wildlife con¯icts

Urban ecosystems are highly dynamic and in con-

stant evolution. Like in natural ecosystems, wildlife

communities ¯uctuate and evolve. New species invade

urban areas (Morneau et al., 1999) and some species

explode in abundance creating con¯icts with people

(Cooper, 1987). These con¯icts need to be properly

addressed and they pose quite a challenge as they are

often caused by inadequate human behavior. Further-

more, since the dynamics of urban ecosystems are still

poorly documented, management actions often have

unexpected results. Pigeons, gulls and starlings some-

times are a nuisance in towns. Several American cities

also have serious problems with urban geese that have

exploded in numbers within urban parks creating

serious habitat degradation problems (Nelson and

Oetting, 1981; Conover, 1987; Breault and McKelvey,

1991). Like urban biodiversity, management of urban

bird problems requires a multi-scale approach as well

as a sociological component. Unfortunately little

research has been done so far on human perception

and appreciation of urban wildlife (Brown et al., 1979;

Lemoine and Sauvage, 1996).

6. Conclusions

Principles used for managing or enhancing biodi-

versity can be applied to urban ecosystems. Because of

the highly dynamic nature of urban ecosystems a small

effort in management can have a great effect on bird

abundance and diversity. As we have shown, actions

are required on several spatial scales simultaneously

and local as well as landscape features are important to

consider. Although we limited our paper to birds and

emphasized species richness, which is only a small

component of biodiversity. Urban ecosystems can be

of high value to a variety of other organisms or to

several other aspects of biodiversity (population struc-

ture, genetic diversity). For example, rare plants or

rare forms of plants can be cultivated in backyards,

maintaining a source of genetic variability; ¯owers

that attract butter¯ies can be grown in parks and even

private lots so that butter¯y diversity increases; crea-

tion of ponds and wetlands in urban parks attracts a

variety of aquatic organisms, etc. Whatever the group

of organisms considered, biodiversity concepts apply.

Enhancement of urban biodiversity can also have

direct economic impacts as residential properties adja-

cent to greenways or urban parks have a higher market

value than similar non-adjacent properties (Hammer et

al., 1974; King et al., 1991, see Luttik this issue). It is

essential to incorporate a sociological component to

biodiversity management in urban areas. No other

ecosystems support such high densities of people so

that desires and perceptions of urban residents must

form an integral part of biodiversity management in

urban ecosystems. These aspects need to be better

quanti®ed.

Research priorities include a greater understanding

of people±wildlife interactions. Such research will

require a joint approach by sociologists and ecologists

and is crucial in the quest for sustainable urban

biodiversity. Finally, another important research prior-

ity is a greater understanding of the importance of

landscape features in local areas and of the dynamics

of exchanges between urban and rural areas. The

ecology and population dynamics of urban birds need

also to be better quanti®ed. Enhancement of biodi-

versity in urban ecosystems, if well done, can have a

signi®cant and positive impact on the quality of life

and education of the increasingly growing urban

population and thus, indirectly facilitate the preserva-

tion of biodiversity in natural ecosystems.

Acknowledgements

We would like to thank G. Falardeau for his assis-

tance. This work was supported by the Canadian

Wildlife Service and the `Centre national de recherche

scienti®que, UniversiteÂ de Rennes I'.

References

Adams, L.W., 1994. Urban Wildlife Habitats: A Landscape

Perspective. University of Minnesota Press, Mineapolis, MN.


Allen, T.F.H., Starr, T.B., 1982. Hierarchy: Perspectives for

Ecological Complexity. University of Chicago Press, Chicago.

Batten, A.L., 1972. Breeding bird species diversity in relation to

increasing urbanization. Bird Study 19, 157±166.

Berger, J.J., 1988. Environmental Restoration: Science and

Strategies for Restoring the Earth. Island Press, Washington

DC.

Bond, W.J., 1993. Keystone species. In: Schulze, E.-D., Mooney,

H.A. (Eds.), Biodiversity and Ecosystem Function. Springer,

New York, pp. 237±253.

Breault, A.M., McKelvey, R.W., 1991. Canada Geese in the Fraser

Valley: A Problem Analysis. Technical Report Series No. 133,

Canadian Wildlife Service, Paci®c and Yukon Region.

Brown, T., Dawson, C., Miller, R., 1979. Interest and attitudes of

metropolitan New York residents about wildlife. Trans. North

Am. Wildl. Nat. Resour. Conf. 44, 289±297.

Cade, T.J., Bird, D.M., 1990. Peregrine Falcons (Falco perigrinus)

nesting in an urban environment: a review. Can. Field-

Naturalist 104, 209±218.

Cavareski, C.A., 1976. Relation of park size and vegetation to

urban bird populations in Seattle, Washington. Condor 78, 375±

382.

Clergeau, P., 1981. Comportements lieÂs aÁ l'alimentation de

l'eÂtourneau (Sturnus vulgaris) en Bretagne: roÃle joueÂ par

certaines variables environnementales et sociales. TheÂse de 3e

cycle Institut des Sciences du comportement et de l'environne-

ment. UniversiteÂ de Rennes I.

Clergeau, P., 1995. Importance of multiple scale analysis for

understanding distribution and for management of an agricul-

tural bird pest. Landscape and Urban Planning 31, 281±289.

Clergeau, P., 1998. BiodiversiteÂ dans les paysages urbains: des

concepts aux applications. Penn ar Bed No. 165±166.

Clergeau, P., Burel, F., 1997. The role of spatio-temporal patch

connectivity at the landscape level: an example in a bird

distribution. Landscape and Urban Planning 38, 37±43.

Clergeau, P., Esterlingot, D., Chaperon, J., Lerat, C., 1996.

Dif®culteÂs de cohabitation entre l'homme et l'animal: le cas

des concentrations d'oiseaux en site urbain. Natures-Sciences-

SocieÂteÂs 4, 102±115.

Clergeau, P., Sauvage, A., Lemoine, A., Marchand, J.P., Dubs, F.,

Mennechez, G., 1997. Les oiseaux dans la ville? Une eÂtude

pluridisciplinaire d'un meÃme gradient urbain. Annales de la

Recherche Urbaine 74, 119±130.

Clergeau, P., Savard, J.-P.L., Mennechez, G., Falardeau, G., 1998.

Bird abundance and diversity along an urban±rural gradient: a

comparative study between two cities on different continents.

Condor 100, 413±425.

Conover, M.R., 1987. The urban±suburban Canada Goose: an

example of short-sighted management? Proc. Eastern Wildl.

Damage Cont. Conf. 3, 346.

Cooper, J.A., 1987. Canada Goose Management at the Minneapolis

Ð St. Paul International Airport. In: Adams, L.W., Leedy, D.L.

(Eds.), Wildlife Conservation in Metropolitan Environments.

National Institute for Urban Wildlife, Ser. 2, Columbia,

Maryland, pp. 175±184.

Cramp, S., Simmons, K.E.L., Ferguson-Lees, I.J., Gillmor, R.,

Hollow, P.A.D., Hudson, R., Nicholson, E.M., Ogilvie, M.A.,

Olney, P.J.S., Voous, K.H., Wattell, J., 1977. Handbook of the

birds of Europe, the Middle East and North Africa Volume 1.

Ostrich to ducks. Royal Society for the Protection of birds,

Oxford University Press, Oxford.

Douglas, I., 1983. The Urban Environment. Arnold, London, UK.

Drasch, G.A., Walser, D., Kosters, J., 1987. The urban pigeon

(Columba livia, forma urbana). A biomonitor for the lead

burden of the environment. Environ. Monitor. Assess. 9, 223±

232.

Dunning, J.R., Danielson, J.B., Pulliam, H.R., 1992. Ecological

processes that affect populations in complex landscapes. Oikos

65, 159±175.

Emlen, J.T., 1974. An urban bird community in Tucson, Arizona:

derivation, structure, regulation. Condor 76, 184±197.

Environment Canada, 1994. Biodiversity in Canada: A Science

Assessment for Environment Canada. Environment Canada,

Ottawa.

Flink, C.A., Seams, R.M., 1993. Greenways: A Guide to Planning,

Design and Development. Island Press, Washington DC.

Gilbert, O.L., 1989. The Ecology of Urban Habitats. Chapman &

Hall, New York, 369 pp.

Hammer, T.R., Coughlin, R., Horn, R., 1974. The effect of a large

urban park on real estate value. J. Am. Inst. Plan. 40, 274±277.

Hohtola, E., 1978. Differential changes in bird community

structure with urbanization: a study in Central Finland. Ornis

Scandinavica 9, 94±99.

Huhtalo, H., Jarvinen, O., 1977. Quantitative composition of the

urban bird community in Tornio, Northern Finland. Bird Study

24, 179±185.

Hunter Jr., M.L., 1990. Wildlife Forests and Forestry: Principles of

Managing Forests for Biological Diversity. Prentice-Hall,

Englewood Cliffs, NJ.

King, D.A., White, J.L., Shaw, W.W., 1991. In¯uence of urban

wildlife habitats on the value of residential properties. In:

Adams, L.W., Leedy, D.L. (Eds.), Wildlife Conservation in

Metropolitan Environments. NIVP Symp. Ser. 2, Natl. Inst.

Urban Wildl., Columbia, MD, pp. 165±169.

Lancaster, R.K., Rees, W.E., 1979. Bird communities and the

structure of urban habitats. Can. J. Zool. 57, 2358±2368.

Laurence, A., Palmaerts, N., 1991. La ville coÃteÂ jardin: refuges

naturels. RNPB, Bruxelles, 48 pp.

Lautenschlager, R.A., 1997. Biodiversity is dead. Wildl. Soc. Bull.

25, 679±685.

Lemoine, A., Sauvage, A., 1996. Les oiseaux dans la ville:

repreÂsentations et pratiques des habitants. In: Clergeau, P. (Ed.),

Les relations hommes-oiseaux-habitats sur des gradients

d'urbanisation: comparaison entre les villes de Rennes et de

QueÂbec. Report CNRS, Laboratoire d'EÂ volution des systeÂmes

naturels et modifeÂs, Univ. de Rennes I, pp. 61±133.

Lucid, V.J., 1974. Bird utilization of habitat in residential areas.

Ph.D. Thesis, Virginia Polytechnic and State University,

Blacksburg, Virginia, 162 pp.

Luniak, M., 1994. The development of bird communities in new

housing estates in Warsaw. Memorabilia Zoologica 49, 257±267.

McDonnell, M.J., Pickett, S.T.A., 1990. Ecosystem structure and

function along urban±rural gradients: an unexplored opportu-

nity for ecology. Ecology 71, 1232±1237.


McDonnell, M.J., Picket, S.P.A., Pouyat, R.V., 1993. The

application of the ecological gradient paradigm to the study

of urban effects. In: McDonnell, M.J., Pickett, S.T.A. (Eds.),

Human as Components of Ecosystems. Springer, New York, pp.

175±189.

McNeely, J.A., Miller, K.R., Reid, W.V., Mittermeier, R.A.,

Werner, T.B.,1990. Conserving the world's biological diversity.

International Union for Conservation of Nature and Natural

Resources, Gland, Switzerland; World Resources Institute,

Conservation International, World Wildlife Fund-US and the

World Bank, Washington, DC, 193 pp.

Michelson, W., 1970. Man and his Urban Environment, A

Sociological Approach. Addison-Wesley, Reading, Massachu-

setts.

Middleton, J., 1994. Effects of urbanization on biodiversity in

Canada. In: Biodiversity in Canada: A Science Assessment

for Environment Canada. Environment Canada, Ottawa,

pp. 15±20.

Morneau, F., DeÂcarie, R., Pelletier, R., Lambert, D., DesGranges,

J.-L., Savard, J.-P.L., 1999. Changes in bird abundance and

diversity in Montreal Parks over a period of 15 years.

Landscape and Urban Planning 44, 111±121.

Nelson, H.K., Oetting, R.B., 1981. An overview of management of

Canada Geese and their recent urbanization. Proc. Int. Water-

fowl Symp. 4, 128±133.

Noss, R.F., 1990. Indicators for monitoring biodiversity: a

hierarchical approach. Conserv. Biol. 4, 355±364.

Noss, R.F., 1992. Issues of scale in conservation biology. In:

Fieldler, P.L., Jain, S.K. (Eds.), Conservation Biology: The

Theory and Practice of Nature Conservation, Preservation and

Management. Chapman & Hall, New York, pp. 240±241.

Noss, R.F., 1993. Wildlife corridors. In: Smith, D.S., Calwood

Hellmund, P. (Eds.), Ecology of Greenways. University of

Minnesota Press, Minneapolis, MN, pp. 43±68.

Nuorteva, P., 1971. The synanthropy of birds as an expression of

the ecological cycle disorder caused by urbanization. Ann.

Zool. Fennica 8, 547±553.

Oliphant, L.W., Haug, E., 1985. Population changes of Saskatoon

Merlins. Raptor Res. 19, 56±59.

Penland, S., 1987. Attitudes of urban residents toward avian species

and species' attributes. In: Adams, L.W., Leedy, D.L. (Eds.),

Integratineg Man and Nature in the Metropolitan Environment.

Proc. Natl. Symp. Urban Wildl., Chevy Chase, New York, pp.

77±82.

Rice, K., 1992. Theory and conceptual issues. Agric. Ecosyst.

Environ. 42, 9±26.

Rohde, C.L.E., Kendle, A.D., 1994. Human well-being, natural

landscapes and wildlife in urban areas. A review. English

Nature Science No. 22.

Salwasser, H., 1990. Conserving biological diversity: a perspective

on scope and approaches. For. Ecol. Manage. 35 (1), 75±90.

Sasvari, L., 1984. Bird abundance and species diversity in the parks

and squares of Budapest. Folia Zoologica 33, 249±262.

Savard, J.-P.L., 1978. Birds in metropolitan Toronto: distribution,

relationships with habitat features and nesting sites. M.Sc.

Thesis, Department of Zoology, University of Toronto, Ont.,

221 pp.

Savard, J.-P.L., 1994. General concepts related to biodiversity.

Biodiversity in Canada: A Science Assessment for Environ-

ment Canada. Environment Canada, Ottawa, pp. 9±40.

Savard, J.-P.L., Falls, B.J., 1982. In¯uence of habitat structure on

the nesting height of birds in urban areas. Can. J. Zool. 59, 924±

932.

Sebba, R., 1991. The landscapes of childhood: the re¯ection

childhood's environment in adult memories and in children's

attitudes. Environ. Behav. 23, 395±422.

Smith, D.G., Gilbert, R., 1984. Eastern Screech-Owl home range

and use of suburban habitats in southern Connecticut. J. Field

Ornith. 55, 322±329.

Tilghman, N.G., 1987a. Characteristics of urban woodland

affecting breeding bird diversity and abundance. For. Ecol.

Manage. 21, 163±175.

Tilghman, N.G., 1987b. Characteristics of urban woodlands

affecting breeding bird diversity and abundance. Landscape

and Urban Planning 14, 481±495.

UNEP, 1995. Global Biodiversity Assessment. Cambridge Uni-

versity Press, Cambridge, 1140 pp.

Wackernagel, M., Rees, W., 1996. Our Ecological Footprint:

Reducing Human Impact on the Earth. The New Catalyst

Bioregional Series, New Society Publishers, 160 pp.

Weber, W.C., 1972. Birds in cities: a study of populations, foraging

ecology and nest-sites of urban birds. M.Sc. Thesis, University

of British Columbia, Vancouver, 269 pp.

West, N.E., 1993. Biodiversity of rangelands. J. Range Manage. 46,

2±13.

Wiens, J.A., 1989. Spatial scaling in ecology. Funct. Ecol. 3, 385±

397.

Williamson, R.D., 1974. Birds in Washington DC. In: Noyes, J.H.,

Progulske, D.R. (Eds.), Wildlife in an Urbanizing Environment.

Proceedings of a Symposium, Spring®eld, Mass. Cooperative

Extension Serv., University of Massachusetts Press, Amherst,

7±9 November 1973.

Jean-Pierre L. Savard is a Research Scientist for the Canadian

Wildlife Service (CWS) in QueÂbec. He holds a bachelor's degree

from UniversiteÂ Laval, QueÂbec, an M.Sc. from the University of

Toronto, Ontario, and a Ph.D. from the University of British

Columbia. He spent 14 years with the CWS in British Columbia,

where he studied the distribution and ecology of molting and

wintering seaducks (scoters, goldeneyes, Harlequin Duck), the

breeding ecology of Barrow's Goldeneye and the Eared Grebe, old-

growth forest birds, and seabirds (Marbled Murrelet). His current

research interests in QueÂbec include urban wildlife ecology, impact

of forest practices on birds, bird survey techniques, seaduck

ecology (breeding, staging, moulting and wintering) and biodiver-

sity concepts. He has adjunct status at several QueÂbec universities

where he co-supervises graduate students.

Philippe Clergeau is a wildlife biologist at Ìnstitut National

de Recherche Agronomique' in France. He had received his

Ph.D. and his `Habilitation a Diriger des recherches' from Rennes

University. He teaches wildlife management and biodiversity

control in agronomic schools and universities, and he collaborates

with a `Centre National de la Recherche Scientifique' team (UMR


EcoBio) on landscape ecology. His research activities focus on

the pest bird biology and management, and on biological

relations between rural and urban areas. He is project leader

for several Publications on relations between humans and animals

in towns.

Gwenaelle Mennechez has just received her Ph.D. from Rennes

University. She has studied behavior and fitness of European

starlings in different landscapes (gradient of urbanisation). She has

participated in research projects on biodiversity and avifauna in

urban areas.


Documents

Biodiversity Concepts and Urban Ecosystems