CR Phase 5 Report 063 Final

8/14/2019 CR Phase 5 Report 063 Final

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GVI Costa Rica

Expedition 063 Report

10th July 18th September 2006


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GVI Costa Rica Expedition 063 Report

10th July 18th September 2006

Submitted in whole to:Global Vision International

COTERC

Submitted in part to:The Ministry of Environment and Energy of Costa Rica (MINAE).

Steven Furino, Waterloo University, Canada26th September 2006

Produced byBritt Larsen, Regional Director Central and Southern America

Rebeca Chaverri, Country DirectorJames Lewis, Expedition Manager

Ulla Kail, Expedition StaffJos Pedro Duarte Costa, Expedition Staff

Lydia Chaparro, Expedition StaffNicole Evans, Expedition Staff

James Guilder, Expedition Staff

And

John Sutcliffe Expedition Member Patrick Coley Expedition MemberSarah Gorman Expedition Member Layla Cole Expedition Member

Anna Robinson Expedition Member Kirsty Sewter Expedition Member

Oliver Davey Expedition Member Sandhya Tillotson Expedition Member

Faye Wilkins Expedition Member Paul McMahon Expedition Member

Oliver Brandwood Expedition Member Jane Haakonsson Expedition Member

Colette O'Halloran Expedition Member Claire Vial Expedition Member

Michelle Meyer Expedition Member David Arscott Expedition Member

Katherine Deacon Expedition Member Kelse Weiser Expedition Member

Natalia Filip Expedition Member Gemma Western Expedition MemberVicky Smith Expedition Member Mark Bacon Expedition Member


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GVI Costa Rica

Address: Estacin Biolgica Cao Palma, Tortuguero, Costa RicaTel: (+506) 709 8052

Email: [email protected] & [email protected]

Webpage: http://www.gvi.co.uk


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1. EXECUTIVE SUMMARY

The fifth 10-week phase of the Costa Rican Global Vision Internal (GVI) Expedition has

now been completed. The expedition has maintained working relationships with local

communities through both English classes and Inter-cambio. The expedition hascontinued to work towards the gathering of important environmental scientific data whilst

working with local, national and international partners. The following projects have been

run during Phase 5:

Jaguar predation on sea turtles. In collaboration with the Costa Rica Ministry of

Environment and Energy (MINAE)

Marine Turtle Monitoring Programme (collaboration with the Canadian Organization

for Tropical Education and Rainforest Conservation (COTERC), MINAE and the

Caribbean Conservation Corporation (CCC))

EBCP Resident Bird Project (collaboration with Steven Furino, Waterloo University,

Canada)

Tourist impact assessment within the Tortuguero National Park (collaboration with

MINAE)

Tourist impact assessment on Cao Palma canal.

English language lessons (collaboration with the San Francisco community and

Evergreen Lodge and Canopy Tours).

1.1. Introduction

The Coastal Rainforest Conservation Expedition at the Biological Station Cao Palma in

Tortuguero, Costa Rica has now completed its fifth phase (5 x 10 weeks).

The expedition to date has assisted in collecting a substantial amount of scientific data.

Although this data is already helping to identify potential future research areas and

providing important data to the national and international scientific community it is still atthe preliminary stage. Methodologies continue to be improved and focused as

experience is gained and improvement to data quality is continuous. A full Annual Report

(to be initiated in December 2006) will collate and summarize all data and enable more

descriptive and accurate analysis.


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Contents

1. EXECUTIVE SUMMARY ...................................................................................... i1.1. Introduction .................................................................................................. iContents ................................................................................................................. iiFigures .................................................................................................................. viTables ................................................................................................................... vii

2. JAGUAR PREDATION ON MARINE TURTLES ................................................. 82.1. Introduction ................................................................................................ 82.2. Aim ............................................................................................................ 92.3. Methodology .............................................................................................. 92.4. Results ..................................................................................................... 102.5. Discussion ............................................................................................... 12

3. SEA TURTLE MONITORING PROGRAMME................................................... 133.1. Introduction .............................................................................................. 133.2. Aim .......................................................................................................... 143.3. Methodology ............................................................................................ 15

3.3.1.

Study site ......................................................................................... 15

3.3.2. Daily track census and nest surveys ................................................ 163.3.3. Night surveys ................................................................................... 163.3.4. Tagging ............................................................................................ 17


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3.3.5. Biometric Data.................................................................................. 173.3.6. Nest Fate, Nest Survivorship and Hatching success ........................ 18

3.4. Results ..................................................................................................... 193.4.1. Daily track census and nest surveys ................................................ 193.4.2. Monitoring of female turtles .............................................................. 233.4.3. Tagging ............................................................................................ 253.4.4. Biometric data .................................................................................. 253.4.5. Turtle disease or injuries .................................................................. 263.4.6. Monitoring of nests ........................................................................... 263.4.7. Nest Fate of nests marked by triangulation ...................................... 273.4.8. Nest survivorship and hatchling success .......................................... 28

3.5. Discussion ............................................................................................... 293.5.1. Daily track census and nest surveys ................................................ 293.5.2. Monitoring of nests, Nest Fate of triangulated nests ......................... 303.5.3. Monitoring of female turtles .............................................................. 313.5.4. Biometric data .................................................................................. 32

3.5.5.

Nest survivorship and hatchling success .......................................... 32

4. EBCP RESIDENT BIRD PROJECT ................................................................. 334.1. Introduction .............................................................................................. 334.2. Aim .......................................................................................................... 34


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4.3. Method ..................................................................................................... 344.3.1. Point Counts .................................................................................... 344.3.2. Area Searches ................................................................................. 354.3.3. Incidental Observations .................................................................... 36

4.4. Results ..................................................................................................... 364.4.1. Survey Data ..................................................................................... 364.4.2. Incidental Observations .................................................................... 414.4.3. Migrants ........................................................................................... 42

4.5. Discussion ............................................................................................... 425. NATIONAL PARK TOURIST IMPACT ASSESSMENT ..................................... 43

5.1. Introduction .............................................................................................. 435.2. Aims ........................................................................................................ 455.3. Methods ................................................................................................... 45

5.3.1. Assessment of terrestrial trail condition ............................................ 455.4. Results ..................................................................................................... 47

5.4.1. Assessment of terrestrial trail condition ............................................ 47

5.5.

Discussion ............................................................................................... 48

5.5.1. Assessment of terrestrial trail condition ............................................ 486. TOURIST IMPACT SURVEY CAO PALMA ................................................... 49

6.1. Introduction .............................................................................................. 49


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6.2. Aims ........................................................................................................ 496.3. Methodology ............................................................................................ 496.4. Results ..................................................................................................... 50

6.4.1. Boat Dock Survey ............................................................................ 506.5. Discussion ............................................................................................... 50

6.5.1. Boat Dock Survey ............................................................................ 507. COMMUNITY WORK ....................................................................................... 50

7.1. Introduction .............................................................................................. 507.2. Aims ........................................................................................................ 517.3. Method ..................................................................................................... 51

7.3.1. Expedition Member training .............................................................. 517.3.2. Teaching .......................................................................................... 52

7.4. Results ..................................................................................................... 527.5. Discussion ............................................................................................... 52

8. Bibliography ..................................................................................................... 549. APPENDIX ....................................................................................................... 58


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Figures

Figure 2-1. Beach distribution of Jaguar tracks, turtle tracks, and dead turtles along the

14.5 miles in Tortuguero National Park. Period: 21st July 12th September 2006...10Figure 2-2 Identified number of Jaguar predated turtles recorded in Tortuguero National

Park. Period: 3rd July 12th September 2006.11Figure 3-1 Seasonal distribution of nests and moons ofC. mydas between June 16th

and September 8th 2006.20Figure 3-2 Seasonal distribution of nests and moons ofE. imbricata, C. caretta and D.

coriacea from June 16th until September 8th 2006..21Figure 3-3 Spatial distribution ofC. mydas nests and moons between mile 0 and mile

3 1/8 on North Beach of Tortuguero.22Figure 3-4 Spatial distribution of E. imbricate, C. caretta and D. coriacea nests and

moons between mile 0 and mile 3 1/8 on North Beach of Tortuguero....22Figure 3-5 Encounter time for all sea turtle species found visiting the North Beach during

night patrol hours.24Figure 3-6 Nesting orientation of the 4 studied species (n=76) on North Beach between

June 16th and September 8th 2006.25Figure 3-7 Green nest fate recorded during morning and night surveys....27 Figure 3-8 Nest fate of nests marked by triangulation...28Figure 4-1 Number of species recorded during AM and PM surveys of the Cleared Areas

and Raphia study sites ..37Figure 4-2 Key species recorded during AM surveys of the Cleared Areas study site37 Figure 4-3 Key species recorded during PM surveys of the Cleared Areas study site38 Figure 4-4 Key species recorded during AM surveys of the Raphia Trail study site39


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Figure 4-5 Key species recorded during PM surveys of the Raphia Trail study site40 Figure 4-6 Migrant species observed during phase 5 in the Cleared Area and Raphia

Trail study sites....42Figure 5-1 Change in path width at eleven different study sites on the trail..47Tables

Table 3-1 Tags applied by the Cao Palma Sea Turtle Monitoring Program from 16th of

June until 8th of September 2006...25Table 3-2 Green mean carapace length, carapace width and clutch size on the North

Beach between June 15

th

and September 8th 2006..26

Table 3-3 Summary of excavation results for one Loggerhead nest (Cc), one

Leatherback nest (Dc) and one Green nest (Cm) on North Beach.29Table 4-1 Incidental species observed during Phase 5.41


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2.2. Aim

The Jaguar project aims to document the presence of Jaguar on the beach of

Tortuguero National Park and their predation of nesting marine turtles.

2.3. Methodology

Jaguar surveys are conducted over the 14.5 mile stretch of beach from the entrance of

Tortuguero National Park (mile 3.5) south to Jalova lagoon (mile 18). At least four

surveyors conduct the survey twice per week when conditions allow, starting from either

Tortuguero or Jalova at dawn. General data such as date, name of researchers,

weather, sand condition and start time is noted at the beginning of the survey. Beach

size (distance from vegetation to high tide mark) is recorded every four miles (at mile 4,

8, 12 and 16) to give an indication of how much beach was exposed during the previous

night. Sand condition and general weather are also recorded every four miles.

During the survey, researchers count the total number of fresh (1-2 nights old) turtle

tracks on the beach, including both half moons (not nested) and full tracks (nested). It

should be noted that during the peak of the C. mydas season these numbers will not be

accurate because of the high numbers of turtle tracks present on the beach.

When fresh Jaguar tracks are encountered the direction of the track (north or south) and

location (mile marker and GPS coordinates) are recorded. The track is then followed

until it ends (goes into the vegetation or is washed away by the tide) and the mile marker

and GPS coordinates are recorded again. As would be expected intense and prolonged

rain, high winds and very dry sand, can reduce the quality of Jaguar prints making data

collection very difficult. As weather conditions vary throughout the year it is possible data

quality will be affected. In order to minimise this Jaguar surveys are undertaken during

and after periods of optimal weather conditions when possible.

Data is also collected on fresh carcasses of turtles killed by Jaguars. This includes

location (mile marker and GPS coordinates), species, point of attack, number of nights

since kill, amount of meat eaten, location of carcass relative to the vegetation, whether

the turtle is on its front or back and any other extra comments/observations.

Photographs of particular features may be taken.


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2.4. Results

A total of 11 surveys were conducted between 21st July and 12th September with an

average time of 9 hours and 30 minutes. A total of 51 surveys have been conducted by

GVI since 11 July 2005.

During this phase, 84 C. mydas were killed by Jaguars. The number of separate sets of

Jaguar tracks found during this phase was 51 and a total of 26,542 turtle tracks1 were

recorded. Figure 2-1 shows the location of turtle tracks, Jaguar tracks, and turtle

carcasses per half mile.

0

2

4

6

8

10

12

14

16

18

20

Mile

4

Mile

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Mile

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Dead turtle

Turtle track 100Jaguar tracks

Figure 2-1. Beach distribution of Jaguar tracks, turtle tracks, and dead turtles along the 14.5 miles in

Tortuguero National Park. Period: 21st July 12th September 2006.

11 Due to the high density of turtle tracks this phase, distinguishing between species was difficult and notundertaken.


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During this phase, all of the turtle carcasses were located between miles 5 and 16.5 with

a high concentration between miles 9 and 11.5. The highest concentration of Jaguar

tracks was between miles 6.5 and 10 and again between miles 12 and 15. The turtle

carcasses found within the high Jaguar activity area make up 80% of the total turtle

carcasses found. Figure 2-2 shows the identified number of turtle killed each week.

0

2

4

6

8

10

12

14

16

18

Week 003/07/06 Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 1011/09/06

Figure 2-2 Identified number of Jaguar predated turtles recorded in Tortuguero National Park.

Period: 3rd July 12th September 2006.

Weather conditions this phase proved to be extremely challenging for data collection

purposes. On two occasions surveys were not completed and ended at mile 15. On

several other occasions the hot weather condition meant that track data towards the end

of the survey was difficult to collect. Although this has some impact on the data it is notthought to have skewed the results significantly.

A high level of Jaguar activity has been recorded during this phase. The National Park

Rangers have reported seeing Jaguar several times this phase. On one occasion it was

reported that three different individuals were seen in one morning.


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On the 8th August a large Jaguar was seen near mile 5.5 (N10 30' 33.1" W83 29' 07.3")

during the survey. The individual was believed to be feeding in the vegetation however

subsequent surveys found no evidence of prey remains.

During the survey on the 29th

August what was believed to be a Jaguar was heard nearmile 14.5 (N10 22 26.0 W83 24 12.1). The incident occurred near a freshly killed dead

turtle. Two weeks later it was observed that the turtle carcass had been dragged further

into the vegetation.

Surveyors on the 9th September encountered two park rangers who had successfully

videoed a pair of Jaguars feeding on a freshly killed turtle near mile 12.5 (N10 25 04.4

W83 25 51.9). It was noted that both individuals appeared in very good health with

excess weight apparent.

2.5. Discussion

Data collected during Phase 5 from mid-July to early September includes the height of

the C. mydas season. C. mydas tracks were seen on all walks throughout the phase in

high numbers. All 84 dead turtles found were C. mydas. The kills that were recent were

always found near Jaguar tracks and many of the turtle carcasses were found in high

Jaguar activity areas.

The majority of C. mydas carcasses found were presumed to be killed by Jaguar. In

some situations confirmation of cause of death was impossible. If a turtle showed signs

of being poached by humans it was not recorded. Most of the turtles were found in the

open area of the beach (n=39), however a high proportion were also found in the

vegetation (n=33). As previously collected data has shown, Jaguars appear to be

consuming only a small percentage of the turtle meat. In the majority of cases the neck

was consumed and occasionally a section of tissue behind the left front flipper. This

method, by which the jaguars feed off the turtles, is confirmed by the video footage

obtained by the rangers.

It is not known why Jaguars kill turtles and then eat only a small amount. However, one

theory put forward is that turtles may be used as training for young Jaguars since they

are easy to approach and kill (Schaller, 1972, Carrillo,pers. comm.) It may also be that

Jaguars exert such a small amount of energy killing turtles that not much meat is


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required to replace the total energy expenditure of the kill (Carrillo,pers. comm.) There

were many other potential Jaguar prey seen on the beach during the surveys, such as a

White-nosed Coati (Nasua narica), Black River Turtle (Rhinoclemmys funerea), Spider

monkeys ( Ateles geoffroyi), Green Iguanas (Iguana iguana), Great Curassows (Crax

rubra), Red Brocket Deer (Mazama Americana), and a species of opossum. ThereforeJaguars may be on the beach in search of any prey species and not turtles exclusively.

Further research on this topic is needed before any conclusions can be made.

From January 2006 to the last walk of Phase 5, which occurred on the 12 th of

September, there have been a total of 104 recorded dead turtles killed by Jaguar. Only

25 C. mydas were killed in all of 1998 and 22 killed in all of 1999. There is much

speculation as to why the numbers of turtles killed by Jaguar are increasing and it could

be due to a combination of factors. The Jaguar population could possibly be increasingin the Park, pushing more Jaguars onto the beach in search of prey. The habitat

destruction of surrounding areas for banana plantations and cattle ranches could be

forcing Jaguars to move towards the coast (Carrillo,pers. comm.) It is also possible that

there is a decline in other prey species, causing Jaguar to prey upon turtles out of

necessity (Trong, 2000).

Surveys will continue to be conducted throughout the year allowing for a better analysis

of an entire year, which will provide much valuable data on the predation of sea turtles

by Jaguars. This data will help to continue improving the monitoring project and will

provide a useful tool for the management and conservation of Jaguars and turtles in

Tortuguero National Park.

3. SEA TURTLE MONITORING PROGRAMME

3.1. Introduction

Over the past 20 years there has been a huge decline in both Leatherback Turtles

(Dermochelys coriacea) (Trong et al., 2004) and Green Turtles (Chelonia mydas)(Trong & Ranking, 2005) due to overexploitation such as illegal harvesting of their meat

and eggs, as well as fishing, contamination and habitat alteration. The D. coriacea is

classified as critically endangered and C. mydas as globally endangered on the IUCN

Red List (IUCN, 2003). In addition to the general decline in sea turtles, Tortuguero and


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the surrounding areas are continuously developing and thus the demand for protection

and conservation of sea turtles and their habitat is growing.

Tortuguero National Park (TNP) was established in 1975 with the main purpose of

protecting sea turtles and the nearby areas of humid lowland forest and beach (A.Castro, pers. comm.) While its protection is contributing to the stability of sea turtle

populations, many beaches surrounding the park are supposedly affected by a high level

of poaching (J. Daigle, pers. comm.). In response to this, COTERC (Canadian

Organization for Tropical Education and Rainforest Conservation) started a five-year

feasibility study in 2004 with the aim of determining nesting populations and poaching

rates of C. mydas and D. coriacea on North Beach (the beach just north of Laguna

Tortuguero) and the occasional Hawksbill (Eretmochelys imbricata) and Loggerhead

turtles (Caretta caretta).

In July 2005 GVI joined COTERC in collecting data on the unprotected North Beach. As

well as collaborating with data collection and analysis, GVI and COTERC share data

with the CCC (Caribbean Conservation Corporation) in order to gain more knowledge

about tagged turtles and to compare poaching rates with turtles nesting on the protected

National Park beaches.

3.2. Aim

According to previous studies conducted by COTERC there is a great amount of illegal

harvest of turtle eggs and to a lesser extent of turtle meat on the North Beach.

By monitoring sea turtle nesting activity on the North Beach we gain information about

the spatial and seasonal distribution of nesting females, the total number of mature

females, the extent of illegal harvest of turtle meat and eggs, as well as natural predation

of nests.

The collected data is intended to be used as base data for the development of a

conservation project on the North Beach aimed to protect both adult females and sea

turtle nests of all sea turtle species during future nesting seasons.

All data will be compared with other important nesting sites like the TNP.


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3.3. Methodology

The methodology used for the marine turtle monitoring program follows the COTERC

and GVI protocol which is adapted from and approved by the CCC.

3.3.1. Study site

The North Beach, which encompasses the study area, is 3 1/8 miles long, about 5

kilometers, and extends from the Tortuguero river mouth (103636,9N - 833152,1W)

at the southernmost point until Laguna Cuatro (103756,3N 833225,7W) in the

north. Although this beach is not located within the TNP boundaries, it is situated within

the Barra Colorado Wildlife Refuge, which, like the TNP, is managed by ACTo (Area de

Conservacin Tortuguero) under MINAE the Costa Rican Ministry of Environment and

Energy.

The limits of the study area are Mile 0 at the Tortuguero river mouth (103551N

833140W), and Mile 3 1/8 at Laguna Cuatro. The entire study area is divided and

marked with mile markers at each 1/8 of a mile (200 meters) from the south to the north

with ascending numbers. This allows for the documentation of spatial distribution and

density of nests along the beach.

The nearest village to the study beach is San Francisco, situated south of mile 0, a

constantly growing community of about 100 residents. Two hotels, Cabinas Vista al Mar

and Turtle Beach Lodge and a few ranchos and houses are located along the study

beach. On the southern side of the Tortuguero river mouth is Tortuguero beach which

the CCC monitors from mile 0 (103551N 833140W) to mile 18 (102146N

832341W) at Jalova lagoon.

The sand of the study beach is black and fine, typical for a high energy-beach. The width

of the nesting beach platform or berm varies from 2 to 38 meters, but the configuration of

the shape and size of the berm changes constantly in response to long shore drift and

exposure levels.

The dominant plants on the nesting beach are members of the morning glory family

(Ipomoea Pes-Caprae), Rea-purslane (Sesuvium portulacastrum) and Rush grass

(Sporobolus virginicus). The berm is bordered by a hedgerow of Cocoplum


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(Chrysobalanus icaco) and Sea grapes (Coccoloba uvifera) with a mixture of Coconut

palms (Cocos nucifera) and various tropical hardwoods behind.

The beach is littered with a variety of debris including logs, coconut husks and a large

amount of plastics, trash, beer bottles etc.

3.3.2. Daily track census and nest surveys

Sea turtles found in this area are Dermochelys coriacea, nesting from March to mid-July,

Chelonia mydas, nesting from June to November, and the occasional Eretmochelys

imbricata and Caretta caretta, both nesting from June to September (Trong et al.,

2004). Surveys were and will be conducted every day and night from the beginning of

March through November 2006.

The daily track surveys started at 6:00 am and lasted until 8:30 am and consisted of

walking the beach between mile 0 and 3 1/8, recording and monitoring tracks and nests

from the night before. The day team identified tracks as full tracks (turtle nested) or half

moons (non-nesting emergences in which the track takes the form of a parabolic curve),

or a lifted turtle (no tracks going back into the sea). The vertical position of the nest on

the beach was identified either as Open (O area of beach which receives 100%

sunlight), Border (B - area where nest is partially shaded by vegetation) or Vegetation (V

- area where nest is constantly shaded by vegetation). Nests were then identified asnatural (if remained in its original state), poached (with at least 2 of the following signs:

stick marks, exposed egg chamber, flies, eggs shells on the sand or human foot prints)

or predated by an animal.

Data was also recorded when encountering dead turtles on the beach. The size, sex,

state of the turtle, and an estimated time of death were recorded. Any obvious sign of an

unnatural death was also recorded such as harpoon marks, machete cuts or blows to

the head and/or limbs and photographs taken. If the turtle had been tagged, the ID

number was recorded and checked against CCC tagging data.

3.3.3. Night surveys

Each night a minimum of one survey team walked the beach between mile 0 and mile 3

1/8 during 5 hours (21:00 to 02:00).


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Since June 5th the survey period was extended by division into 2 shifts (20:30 to 00:30

and 00:00 to 04:00) whenever the number of expedition members made this possible.

The purpose of the night patrols is to collect data from as many turtles as possible.

However, considering that the beach is 3 1/8 miles long and only covered by one nightteam at any time, except when 2 teams meet between 00:00 and 00:30, there is a high

possibility that not all turtles are encountered. In this case their tracks were documented

confirming that there are two sets of tracks, one ascending and one descending the

beach, following the same methodology as used for the day protocol.

When encountering a turtle on the beach, the following data was collected: the date, the

time when the track was found, the species, the activity corresponding with a scale from

1-8 (1-emerging from the sea, 2-selecting nest site, 3-digging body pit, 4-digging egg

chamber, 5-oviposition, 6-covering egg chamber, 7-camouflaging, 8-returning to the sea)

the initials of each member of the team, the mile marker number and the GPS position of

each nest, the orientation of the nesting turtle (turtle facing North, South, East or West)

and the vertical position of the nest on the beach (Open, Border or Vegetation). When

the nesting process was observed the number of laid eggs (for D. coriacea also the

yolkless eggs) was recorded. Any other comments or anomalies observed were noted.

3.3.4. Tagging

D. coriacea females were tagged in the membrane located between the tail and the rear

flipper using Monel #49 tags (National Band & Tag Co., Newport, USA). C. Mydas, E.

imbricata and C. caretta females were tagged in the front flippers just before the primary

scale using Inconel #681 tags. Females were only tagged if they had laid eggs and then

the tagging took place while they were covering the egg chamber, camouflaging the nest

or returning to the sea. Evidence of old tags in the flippers like old tag notches (OTN) or

old tag holes (OTH), were recorded, as well as evidence of trauma or parasites due to

old tags.

3.3.5. Biometric Data

During the oviposition process the clutch size (number of eggs) was recorded by hand

using a plastic glove and a manual counter (clicker). In Leatherbacks the clutch size

includes fertile and infertile eggs.


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For all turtles found after the oviposition process, the Minimum Curved Carapace Length

and the Maximum Curved Carapace Width were recorded by two people using a 300 cm

fibreglass measuring tape. The measurement was taken three times to allow for

precision and the average of the three measurements was calculated.

Minimum Curved Carapace Length (CCLmin): In Leatherbacks CCLmin was

measured from the beginning of the carapace, extending along the side of the

central dorsal ridge, until the tip of the caudal projection. For the three other

species the measurement was taken exactly along the center of the carapace.

Maximum Curved Carapace Width (CCW max): Measured at the widest part of

the carapace from one side to the other.

3.3.6. Nest Fate, Nest Survivorship and Hatching success

Samples of nests were marked using triangulation in order to locate the nests 5 days

after the estimated hatching time. Triangulation was conducted during oviposition using

three pieces of flagging tape (tags) which were attached to the vegetation behind the

nest. The distance from the centre of the egg chamber to each of these tags was

measured to the nearest cm whilst the turtle was laying eggs. The distance to the most

recent high tide line was also recorded. Triangulation allows finding the location of the

egg chamber where the three tag lines cross when the nest is due to be excavated.

Three tags were used to compensate for the loss of any tapes. If one tag is lost it is still

possible to locate the nest using the other two tags.

Marked nests were excavated 5 days after hatching, whereas if there were no signs of

hatching excavation took place 5 days after the average incubation period for each of

the species. Leatherback nests were therefore excavated after a maximum of 75 days of

incubation, while Green, Hawksbill and Loggerhead nests were excavated after a

maximum of 70 days of incubation.

In addition, all nests found hatching on the beach during morning or night surveys were

excavated 5 days after the first hatchling tracks had been encountered.


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For all excavations the number of live and dead hatchlings, egg shells accounting for

more than 50% of an egg, unhatched eggs with no sign of development, unhatched eggs

with embryos and depredated eggs by crabs or other animals were counted.

For all accurately marked and measured nests a nest fate was determined. Nests whichwere not marked or measured correctly, or which accounted for more than one lost

reference were excluded from analysis. The following nest fate categories were applied:

hatched, poached, predated, eroded and flooded. Empty egg chambers were classified

as poached nests. If there was any doubt about the fate of a nest it was categorized as

unknown.

3.4. Results

Data from this phase was collected from the 16 th of June until the morning of the 9th of

September.

The total numbers of morning and night surveys undertaken were 83 and 103,

respectively.

During daily track census a total of 280 miles were walked in a total of 160 hours and 42

minutes, taking an average of 1 hour and 54 minutes to complete the 3 3/8 miles per

census (including 2/8 of a mile of backtracking to Mile 0). Meanwhile, the night surveys

covered 889 miles and were completed in a total of 443 hours and 40 minutes, taking an

average of 4 hours and 20 minutes to walk an average of 5.3 miles per night.


Without taking into consideration the half moons, lifted or dead turtles, 41% (n=80) of the

turtles that came to the beach to nest were seen during the night patrols. The remaining

69% (n=114) were from tracks found but no turtle seen during both nights patrols and

the daily track census. Only 18 turtles were observed doing a half moon.

The tracks encountered on the North Beach were identified as Green, Hawksbill,

Loggerhead and Leatherback turtles. A total of 549 tracks were observed, divided into

192 nests and 357 half moons. The nests were 98% Green (n=188) and 2% Hawksbill

(n=2) whereas no Loggerhead or Leatherback nests were found during this phase.


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0

0,5

1

1,5

2

2,5

3

3,5

June 15-30 July August Sept 1-8

Ei Nests

Ei 1/2 Moons

Cc 1/2 Moons

Dc 1/2 Moons

Figure 3-2 Seasonal distribution of nests and moons of E. imbricata, C. caretta and D. coriacea

from June 16th until September 8th 2006.

Most Green nests were laid in July (n=77) followed by August (n=75), which was the

month with the highest number of Green moons (n=152) registered on North Beach.

August showed the highest total number of Green tracks (n=227) compared to 209

tracks in July. In September 30 nests and 48 half moons have been recorded so far.

Leatherback tracks (n=6) were found in June and July only, the latest being recorded on

July 5th, none of which was classified as a nest.

Hawksbill tracks were found in all four months of the study period with the highest peak

regarding nests occurring in June (n=2), whereas Loggerhead tracks were found in

August only, totaling three moons.


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0

5

10

15

20

25

30

35

40

45

50

01/8

2/8

3/8

4/8

5/8

6/8

7/8

1 11/8

12/8

13/8

14/8

15/8

16/8

17/8

2 21/8

22/8

23/8

24/8

25/8

26/8

27/8

3 31/8

Cm Nest

Cm 1/2 Moon

Figure 3-3 Spatial distribution of C. mydas nests and moons between mile 0 and mile 3 1/8 on

North Beach of Tortuguero.

0

0,5

1

1,5

2

2,5

3

3,5

01/8

2/8

3/8

4/8

5/8

6/8

7/8

1 11/8

12/8

13/8

14/8

15/8

16/8

17/8

2 21/8

22/8

23/8

24/8

25/8

26/8

27/8

3 31/8

Cc 1/2 Moon

Ei Nest

Ei 1/2 Moon

Dc 1/2 Moon

Figure 3-4 Spatial distribution ofE. imbricate, C. caretta and D. coriacea nests and moons between

mile 0 and mile 3 1/8 on North Beach of Tortuguero.


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Regarding the spatial distribution of Green nests on North Beach, the beach at Mile 7/8

together with Mile 2 6/8 accounted for the maximum number of nests (both n=16)

followed by Mile 1 4/8 (n=14). Green moons peaked at Mile 1 (n=35), followed by 2/8

of a mile (n=29) and Mile 7/8 (n=27).

Hawksbill activity was concentrated between Miles 2/8 and 6/8 (2 nests and 1 moon)

as well as between Miles 2 and 2 3/8 (2 nests and 3 moons).

All Leatherback tracks (n=6) were found between mile marker 2/8 and 1 5/8, whereas all

3 Loggerhead tracks (n=3) were registered in the section between Mile 7/8 and 1.

3.4.2. Monitoring of female turtles

During the night surveys, 98 female sea turtles were observed during the 8 possiblenesting activity processes. 3% were emerging from the sea (n=2), 11% were selecting

the nest site (n=9), 28% were digging the body pit (n=22), 21% were digging the egg

chamber (n=17), 13% were in the oviposition process (n=10), 3% were covering the egg

chamber (n=2), 20% were disguising the nest (n=16) and finally, 3% were returning to

the sea (n=2). Other turtles registered on the North Beach were 1 dead Loggerhead

Turtle found on the 28th of June and 3 dead Greens dating from June 20 th, July 5th and

July 30th, of which the Green found on July 5 th was identified as a male.

The earliest turtle coming to the beach at night was found at 20:30 (n=1), while the latest

turtles were registered at 4:00 in the morning (n=2), which corresponds with the end time

of the second night patrol. Any turtles that visited the beach after 4:00 were recorded

during the morning census. The peak nesting activity occurred at 22:00 corresponding to

the total of 14 turtles encountered at this time during the night patrols. See Figure 3-6.


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0

2

4

6

8

10

12

14

16

20:30

21:00

21:30

22:00

22:30

23:00

23:30

0:00

0:30

1:00

1:30

2:00

2:30

3:00

3:30

4:00

Figure 3-5 Encounter time for all sea turtle species found visiting the North Beach during night

patrol hours.

Out of 76 females for which information was collected regarding the orientation during

oviposition, 30% (n=23) were facing West, 18% were orientated towards South (n=14),

13% North (n=10), 12% Northwest (n=9), 11% Southwest (n=8), 9% East (n=7) and 7%

Northeast (n=5), none facing Southeast (n=0). See figure 3-7.

0

5

10

15

20

25

30

35

W

E

N

S

NE

NW

SE

SW


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Figure 3-6 Nesting orientation of the 4 studied species (n=76) on North Beach between June 16th and

September 8th 2006.

3.4.3. Tagging

Of the total females seen during the night patrols, 44% were already tagged (n=42),

whereas 56% (n=53) were newly tagged out of which 4% showed old tag holes or old

tag notches. The tags applied by Cao Palma Sea Turtle Monitoring Program are shown

in table 3-1.

Furthermore one previously tagged Hawksbill and one previously tagged Leatherback

were encountered on the North Beach during night patrols.

CP0020-CP0021 CP0050-CP0090

CP0092-CP0097 CP0152-CP0153

CP0029-CP0033 CP099-CP0112 CP0156-CP0159

CP0037-CP0038 CP0114-CP0118 CP0162-CP0165

CP0122-CP0123

CP0169-CP0170

CP0043-CP0044 CP0127-CP0133

CP0046-CP0048 CP0137-CP0138 CP0175-CP0178

CP0167

CP0172

CP0026

CP0125

CP0039

CP0040

CP0149

Table 3-1Tags applied by the Cao Palma Sea Turtle Monitoring Program from 16th of June until 8th

of September 2006.

A total of 15 Greens nested more than once on the North beach of which 10 nested

twice and 5 were found nesting 3 times. The re-nesting interval averaged at 16 days

(n=16).

3.4.4. Biometric data

The mean carapace length, carapace width and clutch size (fertile and infertile eggs) of

the Green and Hawksbill turtles coming to nest in the North Beach during the studied

period is shown in the Table 3-2. The mean carapace length of newly tagged individualswith no evidence of previous tags (OTH or OTN) was 104.2 cm (n=49), whereas the

mean carapace width was 94.3 cm (n=49). Newly tagged Greens with old tag holes or

old tag notches had a mean carapace length of 106,3 cm (n=4) and a mean carapace

width of 94.3 cm (n=4). Previously tagged Greens averaged at a carapace length of

103.7 cm (n=32) and a carapace width of 94,3 cm (n=30).


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The average number of fertile eggs was 115 for newly tagged Green females (n=25) with

no signs of previous tagging and 98 for newly tagged Greens with old tag holes or old

tag notches (n=2). Previously tagged Greens laid an average number of 131 eggs per

clutch (n=15).

SimpleCCL min (cm) CCW max (cm) Fertile eggs

n x .. n x .. n x ..

Newly tagged Green no OTH/OTN 49 104.2 16 49 94.3 16 25 115 26Newly tagged Green with OTH/OTN 4 106.3 1.49 4 94.3 2.68 2 98 N/APreviously tagged Green 32 103.7 4.9 30 94.3 4.4 15 110.7 19.9

Table 3-2 Green mean carapace length, carapace width and clutch size on the North Beach between

June 15th and September 8th 2006.

One previously tagged Hawksbill as well as one previously tagged Leatherback were

encountered during the study period. The Hawksbill had a carapace length of 90.8 cm

and a carapace width of 79.6 cm, her clutch size amounted to 131 eggs. The

Leatherback female had a carapace length of 144.2 cm and the width accounted for 118

cm, however she did not nest.

3.4.5. Turtle disease or injuries

Due to the use of a different data set, analysis of disease and injury related information

has not been possible for this phase.

3.4.6. Monitoring of nests

Out of 169 Green nests for which a fate was determined during night and morning

surveys 49% seemed to be left in their natural state without any signs of poaching,

erosion or predation (n=82). Based on at least two evidences such as human foot prints,

stick marks, flies, egg shells and/or an exposed egg chamber, 51% of the total nests

were classified as poached (n=86). 1% of nests (n=1) were predated. See figure 3-5.


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50%49%

1%

Poached

Predated

Natural

Figure 3-7 Green nest fate recorded during morning and night surveys.

Of the 4 Hawksbill nests 75% were categorized as natural (n=3) and 25% were classified

as poached (n=1).

3.4.7. Nest Fate of nests marked by triangulation

A total of 14 triangulated and marked nests were due to be dug up during the study

period from June 16th until September 9th. 5 nests could not be found because ofinaccurate measurements, bad angles and lost tags. 9 nests were located using the

measurements taken of which 8 nests were empty and therefore classified as poached

whereas one nest had hatched and was excavated. See figure 3-6 for Nest Fate of

marked nests and table 3-3 for excavation results.


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Figure 3-8 Nest fate of nests marked by triangulation.

3.4.8. Nest survivorship and hatchling success

During morning patrols from June 16th until September 9th 2006 a total of 3 sets of

hatchling tracks were found on the North Beach, for two of which the position of the nestcould be located. These two nests, one Loggerhead and one Leatherback nest, which

had not been triangulated, were excavated a minimum of five days after the tracks had

been encountered and the data collected can be seen in Table 3-3.

Out of 14 nests marked by triangulation, 9 could be located using the measurements

and reference points taken. Only 1 of these 9 nests contained eggs and could therefore

be excavated. See Nest Number 4 on Table 3-3 for the data recorded.

NestCode

SpeciesAlive

HatchlingsDead

HatchlingsShells>50%

YolklessEggs

Unhatchedno Embryo

Unhatchedwith

EmbryoDepredated

TotalEggs

4 Cc 0 0 111 NA 9 0 2 122NA Dc 0 3 47 49 8 8 0 112NA Cm 0 0 77 NA 2 26 0 105

7%

58%

14%

14%

7%

Hatched

Poached/Empty

No tags found

Measurements did not cross

Bad Angles


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Table 3-3 Summary of excavation results for one Loggerhead nest (Cc), one Leatherback nest (Dc)

and one Green nest (Cm) on North Beach.

Neither incubation period nor hatching or emerging success could be calculated due to

missing information regarding the number of eggs laid for the three nests excavated.

3.5. Discussion


The study period from June 16th to September 9th reflects the last month of the

Leatherback nesting season, which on the Caribbean coast ranges from March to mid-

July (Trong et al., 2004), and thus this report does not reflect the total Leatherback

nesting season. Although Leatherbacks continued visiting the beach resulting in six

moon tracks, no additional Leatherback nests could be accounted for during this studyphase. The latest track was found on July 5th, which concluded this years Leatherback

nesting season on the North Beach. The total number of nests for the complete

Leatherback nesting season resulted therefore in 52 nests, whereas the number of

moons amounted to 27 on the North Beach. The large amounts of driftwood on North

Beach could be a barrier for Leatherbacks coming to nest and possibly more efforts

cleaning the beach could increase the number of Leatherback nests. However, an

increase of sea turtle nests, especially of the critically endangered Leatherback and

Hawksbill Turtles on North Beach, should only be aimed for if measures for nestprotection against poaching are implemented.

So far in the season July accounted for the highest number of Green nests (n=77) and a

total of 132 half moons. In August less nests (n=75) were laid, but it was the month with

the highest number of Green moons (n=152) registered on the North Beach, totaling

in the highest number of Green tracks (n=227) compared to a total of 209 tracks in July.

September could possibly equal the number of tracks found in July and August, as after

only a quarter of the month passed, the number of both nests (n=30) and moons

(n=48) is higher (for nests) or almost as high (for moons) as a third of the total

numbers achieved in both July and August. Only at the end of the Green nesting

season, which will conclude around the end of October, will we be able to show the

whole picture of this years Green nesting season on North Beach.


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Nests of the two critically endangered species, the Leatherback and Hawksbill Turtles,

need to be protected by all means, therefore nest protection measures should be

implemented in future nesting seasons. The protection of the globally endangered

Loggerhead Turtle nests should also be a priority, as the low number of nests in the

study area could lead to a complete disappearance of Loggerheads on the North Beach.Regarding globally endangered Greens, the North Beach has to be seen as an

extension of their main nesting area, Tortuguero Beach, where estimated nest numbers

range from about 40,000 to about 160,000 nests per season on the 23 miles of the entire

beach from the Tortuguero river mouth to Jalova lagoon. Green nest protection should

be aimed for on North Beach, but in this case the situation of the local community

regarding their dependence on sea turtle eggs together with the lack of control by the

local authorities make this approach a highly sensitive one. Therefore finding sources of

alternative income as well as raising awareness within the local community together withthe collaboration of the local authorities should hopefully result in the elaboration of a

sustainable sea turtle conservation program on the North Beach.

3.5.3. Monitoring of female turtles

Nesting activity, reflecting the encounter time of sea turtles on the North Beach, peaked

at 22:00 with a continuous high nesting activity until 3:00 am. Regarding the fact that due

to low numbers of volunteers we could only maintain the second night patrol shift (00:00-

4:00) during the first half of the study period, extrapolation of the results after 00:30

make the late night hours until 3:00 am the time of highest overall activity, although the

activity peak still remains at 22:00.

For this reason, the division of the night patrols in two shifts (20:30 to 00:30 and 00:00 to

04:00), covering all the peaks of the higher density hours, should be aimed for

throughout the peak nesting season.

The favoured orientation of 84% of turtles while nesting was west, south, north,northwest and southwest, reflecting an orientation towards or parallel to the vegetation,

whereas 16% of turtles faced East or Northeast and none Southeast, reflecting a

seaward orientation.


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Four dead turtles were found on North Beach of which one was a Loggerhead Turtle.

The killing of adult sea turtles causes a major impact on nesting populations, in that it

reduces the number of re-nesting of adult females and subsequently less numbers of

hatchlings reach the age of nesting within a couple of decades. Therefore it should be of

highest priority to stop the continuous killing of sea turtles on the North Beach by askingthe local authorities to act when such events occur as well as involve the local

community more in sustainable development initiatives and conservation.

3.5.4. Biometric data

Mean carapace length measurements of previously tagged Greens were smaller than

those of newly tagged with evidences of old tag or notches and smaller than the newly

tagged without evidences. Newly tagged Greens with old tag holes or old tag notches

had a bigger mean carapace length than those without signs of previous tags. The mean

carapace width measurements were the same for all three categories of Greens.

In theory (L. Chaparro, pers. comm.) newly tagged turtles, which are assumed to be

younger, are in general smaller than previously tagged turtles, which are assumed to be

older. One of the reasons for the contradiction of this theory, shown in the above results,

could be that this is the first year that a tagging program is taking place on this beach.

Consequently, we are not able to identify re-migrating turtles (turtles that came to nest in

previous years) from the neophytes (turtles that reach the sexual maturity for the first

time). In this way, the inter-nesting females that were not previously tagged by other

turtle monitoring programs do not present any evidence of old tag holes or notches.

Thus they are mixed with the neophytes that come to nest for the first time, and the

mean carapace measurements do not necessarily reflect the age of the turtles.

3.5.5. Nest survivorship and hatchling success

Additional to five Leatherback nests recorded hatching during the previous study period

from 2nd of March until 15th of June, one more Leatherback nest was found hatching

during this study phase from June 16th until September 9th. Out of the six marked

Leatherback nests only three could be located and all of them were found empty when

dug up, therefore the only excavation results obtained were from an unmarked nest out

of which 44 hatchlings reached the sea.


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The only Loggerhead nest excavated was a marked nest, but nevertheless the number

of eggs laid could not be found in the note books and therefore hatching and emerging

success could not be calculated. 111 Loggerhead hatchlings reached the sea.

Regarding the excavated Green nest it is hoped that more Green nests will be foundhatching during the next study period, which will start with the night patrol on September

9th, and the obtained results will allow the calculation of hatchling and emerging success

for Greens on the North Beach.

4. EBCP RESIDENT BIRD PROJECT2

4.1. Introduction

Over the past 40 years northeast Costa Rica has been under much scientific focus due

to its extensive primary lowland and coastal rainforests and Tortuguero in particular also

because of the largest nesting colony for the endangered Green (Chelonia mydas). Due

to the geographical location, a large amount of investigation into the migratory avifauna

of the New World has also been conducted in this part of Costa Rica.

Though quite a bit is known about Costa Rican birds, and in particular the migratory

species that either winter in Costa Rica or pass through, an astonishing amount remains

to be learned about the residential species. Because of this and the growing concerns

about the status of birds of the rainforests in Mesoamerica, this long-term monitoringprogram has been established in the area of Tortuguero. Estacin Biolgica Cao Palma

(EBCP) is based 7km north of Tortuguero National Park on the Cao Palma canal that

runs parallel to the coast.

This protocol is intended to gather data that will shed light on the natural history of

resident birds as well as the migratory species in 2 different habitats using area

searches, point counts.

2 The information in the introduction and methodology of this section of the report has been

directly taken from the protocol developed by Steven Furino. Some adaptations have been made

where field experience has identified more suitable ways of undertaking the research.


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The GVI protocol is a slight modification of the protocol created by Steven Furino, of

Waterloo University Canada, to take into account the use of a number of different

recorders. In all other aspects the research follows the original protocol.

4.2. Aim

This research program is intended to accumulate data that will allow researchers to

answer, at least in part, the following questions.

How frequently do pelagic species visit the Caribbean Coast? Is there any pattern to

their visits?

When, exactly, do resident birds breed in coastal areas and swamp forests?

What can be learned about the breeding and nesting behaviour of resident birds?

Are breeding activities and climate correlated?

4.3. Method

This project has adopted standard survey techniques so that suitable comparisons can

be made against data sets gathered by other researchers.

For each Resident Bird Project (RBP) survey the following general data is recorded:

Name of study site

Name of surveyors

Date of survey

Cloud cover

Ground moisture

Rainfall

Leaf Drip

Start time (using a 24 hour clock)

End time (using a 24 hour clock)

For further information on the categories used to assess climatic conditions see

appendix A.

4.3.1. Point Counts

A point countsurvey records all species seen or heard in a ten minute period at a

predetermined location. Point counts are conducted in conjunction with area searches.

See appendix B for exact locations for each point count station.


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Point counts allow researchers to use statistical techniques to assess the density of bird

populations.

Surveyors record all study species positively identified in an exact 10 minute span. The

point count stations are not left during this period unless it aids in the identification of abird.

For each positive record made the following data should be collected:

Point count station at which species was observed

Time at which species was first recorded

Number seen or heard (S: seen only, H: heard only, SH: seen and heard)

Distance from observers (0-10m, 11-25m, 26-50m, 50m +)

Height within habitat (G: ground, L: Low, M: Medium, H: High, A: Arial)

When possible, the number of males, the number of females and the number of sub-

adults/adults

Any notes on breeding plumage or behaviour

Examples of behaviours which are recorded include: courtship displays; nest building;

copulation; and feeding young (see appendix C for further details). For this protocol, only

behaviours that are strongly correlated with probable or confirmed breeding are

recorded.

4.3.2. Area Searches

An area search records all species seen or heard while searching a predetermined area.

See appendix B for exact locations of each area.

Within each area, sectors have been selected to aid with data collection and analysis.

These sectors have been selected on various habitat variables and enable a similar unit

effort to be used on all surveys.

For each area search as with the point counts only positively identified species are

recorded. For each positive record made the following data was collected:

Station code at which species was observed


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Time at which species was first recorded

Number seen or heard (S: seen only, H: heard only, SH: seen and heard)

Distance from observers (0-10m, 11-25m, 26-50m, 50m +)

Height within habitat (G: ground, L: Low, M: Medium, H: High, A: Arial)

When possible, the number of males, the number of females and the number of sub

adults/adults

Any notes on breeding plumage or behaviour

4.3.3. Incidental Observations

An incidental observation is an observation made while one is not engaged specifically

in area searches or point counts. Incidental observations cover all of the other times of

day and night when birds might be observed. Only species that have been classed asrare or vagrant in the Widdowson and Widdowson Tortuguero species checklist 2004

were recorded.

4.4. Results

4.4.1. Survey Data

During Phase 5 a total of 19 RBP surveys were undertaken. Of these 10 were

undertaken on the Cleared Areas study site (5 AM surveys and 5 PM surveys), and 9

were undertaken on the Raphia Trail (5 AM surveys and 4 PM surveys). A total of 66

species were recorded within the Cleared Areas study site and a total of 33 species

were recorded within the Raphia Trail Study Site. Figure 4-1 shows there are more

species observed during AM surveys than PM surveys in both study sites.


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0

10

20

30

40

50

60

70

Cleared Areas Raphia Trail

NumberofSpecies

AM

PM

Figure 4-1 Number of species recorded during AM and PM surveys of the Cleared Areas and Raphia

study sites

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

BarnSwallow

Bay

Wren

Black-crowned

Tityra

CinnamonB

ecard

Commonnigh

thawk

GreenIbis

Purple-CrownedFairy

Red-lored

parrot

Scarlet-rumpedCacique

Spottedsan

dpiper

Stripe-throatedHermit

TennesseeW

arbler

thick-billedseed-finch

Violet-crowned

WhiteIbis

White-crowned

parrot

White-NeckedJacobin

Yellow-belliede

laenia

Black-stripedsparrow

Golden-hoodedta

nager

Great-tailedg

rackle

Lineatedwoodpecker

Olive-throatedPa

rakeet

Palmta

nager

Purple

Martin

Streak-h

eaded

White-breastedwood-wren

Yelloww

arbler

Yellow-OliveFlyc

atcher

CommonTody-Flyc

atcher

Long-billedHermit

prothonotaryw

arbler

Purple-throatedfru

itcrow

Short-billedpigeon

Socialflyc

atcher

WesternSlaty-Antshrike

Blackvulture

Blue-blackgra

ssquit

Black-cheekedwoodpecker

Blue-graytanager

BronzyHermit

Collaredaracari

Stripe-breasted

Wren

clay-coloredrobin

LesserGreenlet

Rufous-tailedhummingbird

White-Collaredmanakin

Black-cowled

oriole

Housewren

Olive-backedEuphonia

TropicalKingbird

Boat-billedFlyc

atcher

Mealy

Parrot

Montezumaoropendola

Black-mandibledtoucan

GreatKis

kadee

Keel-billedtoucan

Slaty-tailed

trogon

VariableSee

deater

Figure 4-2 Key species recorded during AM surveys of the Cleared Areas study site


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Figure 4-2 shows the top five species for the AM surveys: Variable Seedeater

(Sporophila corvine) Slaty-Tailed Trogon (Trogon massena), Keel-billed Toucan

(Ramphastos sulfuratus), Great Kiskadee (Pitangus sulphuratus) and Black-mandibled

Toucan (Ramphastos swainsonii).

The rare bird species (based on Widdowson and Widdowson Tortuguero species

checklist 2004) seenduring the AM cleared area survey were: White Ibis (Eudocicimus

albus), Black-crowned Tityra (Tityra inquisitor), and Purple-crowned Fairy (Heliothryx

barroti).

0

1

2

3

4

5

6

7

8

9

10

Bare-throatedTiger-Heron

Bicoloredantbird

Black-cheekedwoodpecker

Black-stripedsparrow

LesserGreenlet

MaskedTityra

MealyParrot

Olive-sidedflycatcher

Socialflycatcher

TropicalKingbird

TurkeyVulture


White-crownedparrot

White-ringedFlycatcher

Yellow-belliedelaenia

Black-mandibledtoucan

Blue-blackgrassquit


Rufous-tailedhummingbird

Boat-billedFlycatcher

BronzyHermit

clay-coloredrobin

Collaredaracari

Golden-hoodedtanager

Slaty-tailedtrogon

White-Collaredmanakin

Blue-graytanager

CommonTody-Flycatcher

Blackvulture

VariableSeedeater

Keel-billedtoucan

Montezumaoropendola

GreatKiskadee

Figure 4-3 Key species recorded during PM surveys of the Cleared Areas study site

For the PM survey the top five species were (see figure 4-3): Great Kiskadee (Pitangus

sulphuratus), Montezuma Oropendola (Psarocolius Montezuma), Keel-billed Toucan

(Ramphastos sulfuratus), Variable Seedeater (Sporophila corvine) and Black Vulture

(Coragyps atratus). No rare species were recorded.


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0

1

2

3

4

5

6

7

8

9

Black-throatedTrogon

Commonblack-hawk

GreatGre

enMacaw

Long-billedHermit

NorthernBarred-Wo

odcreeper

Pale-billedW

oodpecker

Purple-throate

dfruitcrow

Wedge-billedwo

odcreeper

White-Collare

dmanakin

White-NeckedJacobin

Yellow-Olive

Flycatcher

Americ

anredstart

Bright-rumpedattila

Lineatedw

oodpecker


Slaty-ta

iledtrogon

Black-mandib

ledtoucan

Keel-billedtoucan

Paltry

Tyrannulet

Colla

redaracari

GreenIbis

Montezumaoropendola

Rufescenttiger-heron

Short-billedpigeon


M

ealyParrot

Stripe-brea

stedWren

WesternSlaty-Antshrike

Chestnut-backedantbird

LesserGreenlet

Figure 4-4 Key species recorded during AM surveys of the Raphia Trail study site

The top five species observed in the AM Raphia trail survey were: Lesser greenlet

(Hylophilus decurtatus), Chestnut-backed antbird (Myrmeciza exsul), Western slaty-

antshrike (Thamnophilus atrinucha), Stripe-breasted wren (Thryothorus thoracicus) and

Mealy Parrot (Amazona farinose).

The only rare species observed during the AM survey on the Raphia Trail was the

Rufescent Tiger-heron (Tigrisoma lineatu), with two observations made at location A17,

and one observation at A18. A juvenile was seen at A56 during the same AM survey as

well as another adult individual (mentioned above) at A17. According to Widdowson and

Widdowson (2004), the abundance of this species is rare; therefore, we considered it as

an important observation to mention, since there is no similar record from the previousphases.

.


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0

1

2

3

4

5

Americanredstart

Black-throated

Trogon

Gray-neckedw

ood-rail

Littletinamou

Northern

Barred-

Woodcr

eeper


Rufescenttige

r-heron

Short-billed

pigeon

Stripe-breaste

dWren

Violet-c

rowned

Woodnymph

White-breastedwood-

wren

White-C

ollared

man

akin

Black-ma

ndibled

touc

an

Collared

aracari

LesserG

reenlet

Long-billed

Hermit

MealyParrot

Mon

tezuma

orop

endola

Olive-throated

Parakeet

Chestnut-backed

antbird

Species

NumberofIndividuals

Figure 4-5 Key species recorded during PM surveys of the Raphia Trail study site

The only rare species observed during the PM survey on the Raphia Trail was the

Rufescent Tiger-heron (Tigrisoma lineatu).

Breeding evidence of one species was recorded during the Phase 5 surveys. Species

confirmed as breeding include the White-Collared Manakin (Manacus candei) where an

adult female was seen leaving the nest which contained two eggs. This was observed at

A40 on the Raphia Trail on 9th September. This is outside of the usual breeding season

(April to August) according to Stiles & Skutch (2003).


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4.4.2. Incidental Observations

Table 4-1 Incidental species observed during Phase 5.

DATE COMMON

NAME

SPECIES SEX

HEARD

SEEN

IND.

LOCATION COMMENTS

11/09/06 Roseate

Spoonbill

Platalea ajaja S 3 Jalova

14/09/06 Roseate

Spoonbill

Platalea ajaja S 1 Tortuguero

Canal

20/08/06 Wood Stork Mycteria

americana

S 1 Tortuguero

Cerro trail

3/09/06 Ruddy

Turnstone

Arenaria

interpres

S 1 North Beach

8/09/06 Black & White

Owl

Ciccaba

nigrolineata

H + S 2 Clearing

Biological

Station

15/08/06 Green-

breasted

Mango

Anthracothorax

prevostii

F S 1 North Beach

trail

23/08/06 Green-

breasted

Mango

Anthracothorax

prevostii

F S 1 North Beach

trail

20/08/06 Blue-tailed

Hummingbird

Amazilia cyanura Mist

netted

1 Roca Trail CCC Banding

team Lead By

Sergio Vilchez

27/08/06 Black-

crowned

Tityra

Tityra inquisitor M S 1 North beach

trail

Mixed Flock

15/08/06 Orchard

Oriole

Icterus spurius M S 2 North beach

trail

Mixed Flock

15/08/06 Yellow-

crowned

Euphonia

Euphonia

luteicapilla

? H 1 Cabinas Vista

al Mar -

Clearing


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Green Ibis (Mesembrinibis cayennensis) are frequently recorded in the vicinity of the

station. Due to this it is recommended that they should no longer be recorded as a rare

species for this study, although they are described as such by Stiles & Skutch (2003).

4.4.3. Migrants

Migration of North American, Boreal and Temperate species occurs mainly during

August to October. Observations during phase 5 for the non-passerines may not

accurately reflect true abundances due to study limitations. This includes: periods of

survey (for example, night hawks mostly migrate at dusk) and study sites (where it is

difficult to accurately count aerial species such as the Hirundinidae family).

0

5

10

15

20

25

30

Spottedsandpiper

PurpleMartin

Yellowwarbler

TennesseeWarbler

Olive-sidedflycatcher

Americanredstart

prothonotarywarbler

BarnSwallow

PurpleMartin

Commonnighthawk

Migrant Species

NumberofIndividuals

Figure 4-6 Migrant species observed during phase 5 in the Cleared Area and Raphia Trail study sites.

4.5. Discussion

The EBCP Resident Bird Project monitoring surveys began in July of 2005 and will

continue for several years. As the study is only in its fifth phase, this early set of data can

not be taken as indicative of trends for local bird species.


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During Phase 5 a total of 19 RBP surveys were undertaken. The original aim was to

achieve an equal number of surveys per study site and an equal number of dawn and

dusk surveys within each study site. The complexities of the expedition meant that this

was not always possible however the numbers were kept relatively constant

Data collected on individual study sites will be used over time to assess how certain

populations are changing, if at all, and how they use the specific habitat over the course

of a year.

The findings from this phase do not highlight any unexpected or unusual patterns in the

local bird populations.

The EBCP Resident Bird Project surveys undertaken during Phase 5 have assisted in

increasing the overall data set. They have also helped in identifying areas where

continued improvement to the methodology is required in order to gain the most useful

and accurate data possible.

5. NATIONAL PARK TOURIST IMPACT ASSESSMENT

5.1. Introduction

With 622,000 ha or 12.2% of the country set aside in preserves, Costa Ricas National

Parks stand as a model for the preservation of biodiversity in the tropics (Boza, 1993).

These magnificent wild lands provide shelter for some 205 species of mammals, 845

species of birds, 160 species of amphibians, 218 species of reptiles and 1,013 species

of freshwater and marine fishes that have been discovered in the country (Boza, 1993).

10,000 of species of vascular plants have been identified to date which account for

almost 4% of the total number of plant species in the world (Boza, 1993). This diversity

of wildlife is encapsulated within a variety of habitats found in Costa Rica.

Tortuguero National Park, located on the upper Caribbean coastline of Costa Rica was

established between 1970 and 1971 along with 3 others in this region. The Park is

managed and protected by the Costa Rican Ministry of Environment and Energy

(MINAE). Terrestrial sections of the National Park consist of primary rainforest and

flooded swamplands which extend from the Caribbean coastline to the foothills of the

central Costa Rican mountain range. Within the Parks boundaries exists a sequence of

terrestrial and aquatic trails clearly marked to allow tourists the opportunity to experience


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the impressive species richness of the areas 2,200 species of plant, 375 birds, 125

mammal species and 124 species of reptiles (Hocken et al., 1992; cited in Hill et al.,

1997). Controversy has arisen in recent years over the extent to which humans uses of

such reserves may have adverse effects of wildlife. These uses include tourism,

recreation and industrial development. Therefore there is considerable conservationinterest in quantifying the effects of such disturbance upon the diversity that exists here

(Hocken et al., 1992; cited in Hill et al., 1997).

The flow of tourists to the National Park is regulated by MINAE. Greater accessibility to

this region has begun to create an additional constant influx of tourist groups into the

Park using both the aquatic and terrestrial trails. Since 1998 annual totals of visitors to

the Park have risen from 15,000 to 92,000 in 2005 (C. Calvo, pers. comm.) Although

tourism is encouraged by the local community, MINAE and the national economy, acertain balance between the Parks human activity and the conservation of these fragile

ecosystems should be respected. Thus there is a potential threat to the biodiversity of

the Park due to excessive stress from this continuous activity. Initiation of this study is in

direct response to growing concerns of the negative impact tourism is having on the

National Park.

Assessing the severity of the effects of disturbance has important practical

consequences; if it has serious impacts conservationist are justified in recommending

that access to wildlife areas be limited (Burger, 1981; cited in Gill et al., 2001). However

if the impacts of disturbance are trivial then such measures cannot be justified.

Restricting human access to these areas can be expensive and time consuming but

more importantly it goes against the increasing view that rural access should be

increased. In many cases access to areas of conservation value can be the optimum

way to protect them as it increases the value placed on them by society (Adams, 1997;

cited in Gill et al.,2001).

The impact of tourist presence can also be measured through direct measurements of

physical factors such as path width, level of erosion and litter. All of these factors enable

a very simple assessment of tourist impact to be produced whilst enabling a useful and

often immediate tool for management.


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Funded by the European Union, in 2005 MINAE developed a Management Plan for

visitors to Tortuguero National Park. GVI were requested to initiate and implement the

Tourist Impact Assessment in order to provide data for an objective and quantitative

evaluation of the impact of tourism in this National Park. In order to gain as much data

on tourist impact a number of studies recommended in the Management Plan have beeninitiated examining both environmental and physical effects.

5.2. Aims

The Tortuguero National Park Tourist Impact Assessment aims to provide MINAE with

suitable data to aid with management decisions in relation to tourist use of the parks

resource. This is achieved through a variety of survey methods that assess physical and

ecological characteristics of the National Park.

5.3. Methods

Four phases of data collection have been undertaken by GVI since October 2005. This

baseline data has resulted in a good understanding of the ecological systems operating

in and around the park. As this understanding continues to develop, methodology is

adapted to yield the most beneficial results possible.

The National Park Tourist Impact Study this phase has been directed exclusively

towards the assessment of the terrestrial trail condition.

5.3.1. Assessment of terrestrial trail condition

The presence and development of extensions and divergences along the Gaviln Trail

system in Tortuguero National Park was assessed.

The Gaviln Trail is approximately 2000m in length and is open to tourists. The path was

originally designed to be 2m wide along its entire length. When the trail becomesflooded, visitors have found other routes to make their way around the trail. As a result of

this, the path width has been extended in certain areas and in other areas divergences

(a separate trail through the vegetation) have been created. In areas where there are

raised boardwalks or log paths, there are no extensions.


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Measurements of the extensions and divergences have been taken at 11 sites along the

trail. The aim of this was to discover the rate of change to the path width and to show

that the trail requires maintenance work. To enable the rediscovery of each site, the

distance from the entrance was measured (in metres).

At the beginning of each extension, a pole was placed in the vegetation on the left of the

trail. The pole was spray painted white at the tip and labelled with a number, ranging

from one to eleven. This pole acts as a marker for the point. A ten metre transect was

then measured down the middle of the path. At the five meter point, which was generally

the widest part of the extension, a small pole was placed at either side of the trail. These

poles were also spray painted white at the tip.

The reason for using smaller poles at these points was so not to impact the route that

the tourists may take. The width was measured from the middle of one pole to the

middle of the other pole (along the ground) and recorded. The width was then measured

at every other metre point along the trail (about one meter off the ground), giving eleven

measurements, but no other poles were placed in the ground. Instead of measuring from

pole to pole at these points, the widest parts were estimated by the use of plants (over

hanging branches, tree trunks, etc) and any footprints that led of the main path. For the

divergences, the total width was recorded. If the divergence was on the left, the

measurement would be taken from the widest point on the right side of the main path, to

the widest point on the left hand side of the divergence. This was generally measured

through the vegetation but in some cases this was not possible. Where the vegetation

was too thick or if there was a tree in the way, the width of the main path and the

divergent path were measured and recorded separately. Any observations that would

help the re-measuring of the points were also recorded, such as the angle at which the

transects were measured out. The extensions were sometimes at bends, and it was

therefore not possible to place the transect down the middle of the path.

Every site was then measured and recorded on a weekly basis, monitoring the rate of

change. When there is change at the five meter point, a new pole is placed at the edge

of the new trail and the width to this pole is taken. The primary pole is left in place.


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5.4. Results


During this phase (10th July 17th September) GVI collected data on 11 sites with

extensions or divergences along the main trail. All of these extensions and divergenceswere found between 250 m and 1000 m from the headquarters of Cuatro Esquinas. Due

to the malfunction of the GPS under the rainforest canopy the exact location of these

points could not be recorded.

The maximum width recorded was 10.22m (at site 9). The full set of results can be seen

in appendix D. The average change in width, for each site, between the samples is

shown in Figure 6.1.

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

1 2 3 4 5 6 7 8 9 10 11

Site Number

Changein

PathWidth(M)

Figure 5-1 Change in path width at eleven different study sites on the trail

There was a maximum average change in width of 0.52m at site 9 and at site 4 there

was no sign of change.


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5.5. Discussion


From the two surveys that have been carried out, a small change in the path width (see

Figure 5.1) has been seen. However these changes cannot be seen as significant asthere are both increases and decreases in the path width at every site. This is probably

due the difficulties associated with measuring the trail accurately. The results however,

do show that there has been a definite erosion of the path boundaries since the trail was

made to its original two metre wide specifications. At some points the path width has

increased up to as much as ten metres and there were also clear divergences where

visitors had taken alternative routes.

The data set currently cannot provide any definitive results and due to the same sample

size the results should be assessed with caution. The trail will require an ongoing

monitoring program in order to produce any useful data.

Although this phase has seen a high level of tourist activity on the trail there has been

very little rain during these surveys. The trail has been dry and there has been no reason

for the tourists to detour from the main trail. It is very possible that dramatic changes to

the trail width will only occur when the trail is flooded. Thus there may be no changes for

a long period of time, and then sudden dramatic changes during times of heavy rain.

Distinguishing where the border of the path is, when there are no poles marking them,

has proved to be a challenge. This is the most likely cause of the variations in the

measurements between the samples. At site 11, increase of 2.39m was measured (see

Appendix D). The probability of this amount of erosion occurring in one week is v

Documents

CR Phase 5 Report 063 Final