phase 6 064 science report final

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GVI Costa Rica

Expedition 064 Report

10th October 18th December 2006


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GVI Costa Rica Expedition 064 Report

10th October 18th December 2006

Submitted in whole to:Global Vision International

COTERCSteven Furino, Waterloo University, Canada

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

Produced byRebeca Chaverri - Country DirectorJames Lewis - Expedition Manager

Ulla Kail - Expedition StaffJos Pedro Duarte Costa - Expedition StaffJulie Jackson - Expedition StaffFaye Wilkins - Expedition StaffOliver Davey - Expedition StaffNatalia Filip - Expedition Staff

And

Edited byBritt Larsen - Regional Director

GVI Costa Rica

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

Email: [email protected]

Web page: http://www.gvi.co.uk

Timothy LandryExpedition Member

Richard ChinnExpedition Member

Carol TervetExpedition Member

Nina FarrimondExpedition Member

Brianne SmithExpedition Member

Kate CaldwellExpedition Member

Kelly SmithExpedition Member

Andrew ShultExpedition Member

Nicola FoleyExpedition Member

Sau Pik WongExpedition Member

Aysha HamisiExpedition Member

Pauline TanExpedition Member

Robert BurnsExpedition Member

Laura HallExpedition Member

Gabriel JimenezExpedition Member


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1. EXECUTIVE SUMMARY

The sixth 10-week phase of the Costa Rican Global Vision International (GVI) Expedition

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

communities through both English classes and local community events. The expeditionhas continued 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 064:

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

Environment and Energy (MINAE).

Jaguar camera trapping in Tortuguero National Park (TNP). In collaboration with

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).


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1.1. Introduction

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

Tortuguero, Costa Rica has now completed its sixth phase (six 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 at

the 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 January 2007) will collate and summarize all data and enable more

descriptive and accurate analysis.


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List ofContents

1. EXECUTIVE SUMMARY ........................................................................................... i1.1. Introduction ...................................................................................................... iiList ofContents ........................................................................................................ iiiList of Figures ........................................................................................................... viList of Tables ........................................................................................................... viii

2. JAGUAR PREDATION ON MARINE TURTLES ....................................................... 92.1. Introduction ...................................................................................................... 92.2. Aim ................................................................................................................ 102.3. Methodology .................................................................................................. 102.4. Results ........................................................................................................... 112.5.

Discussion ..................................................................................................... 13

3. CAMERA TRAPPING ............................................................................................. 14

3.1. Introduction .................................................................................................... 143.2. Aim ................................................................................................................ 153.3. Methodology .................................................................................................. 15

3.3.1. Study Site ............................................................................................... 153.3.2. General .................................................................................................. 153.3.3. Setting the cameras ............................................................................... 163.3.4.

Checking the cameras ............................................................................ 17

3.3.5. Data entering and analysis ..................................................................... 17

3.4. Results ........................................................................................................... 183.5. Discussion ..................................................................................................... 19

4. SEA TURTLE MONITORING PROGRAMME......................................................... 194.1. Introduction .................................................................................................... 194.2. Aim ................................................................................................................ 204.3. Methodology .................................................................................................. 20

4.3.1. Study site ............................................................................................... 214.3.2. Daily track census and nest surveys ...................................................... 224.3.3. Night surveys ......................................................................................... 224.3.4. Tagging .................................................................................................. 234.3.5. Biometric Data........................................................................................ 234.3.6. Nest Fate, Nest Survivorship and Hatching success .............................. 24


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4.4. Results ........................................................................................................... 254.4.1. Daily track census and nest surveys ...................................................... 254.4.2. Monitoring of female turtles .................................................................... 294.4.3. Tagging .................................................................................................. 314.4.4. Biometric data ........................................................................................ 324.4.5. Turtle disease or injuries ........................................................................ 334.4.6. Monitoring of nests ................................................................................. 334.4.7. Nest Fate of nests marked by triangulation ............................................ 344.4.8. Excavation Results, Hatching and Emerging success ............................ 34

4.5. Discussion ..................................................................................................... 364.5.1. Daily track census and nest surveys ...................................................... 364.5.2. Monitoring of female turtles .................................................................... 374.5.3. Biometric data ........................................................................................ 374.5.4. Monitoring of nests ................................................................................. 384.5.5. Excavation results, hatching and emerging success .............................. 39

5. EBCP RESIDENT BIRD PROJECT ....................................................................... 395.1. Introduction .................................................................................................... 395.2. Aim ................................................................................................................ 405.3. Method ........................................................................................................... 40

5.3.1. Point Counts .......................................................................................... 415.3.2. Area Searches ....................................................................................... 425.3.3. Incidental Observations .......................................................................... 42

5.4. Results ........................................................................................................... 425.4.1. Survey Data ........................................................................................... 425.4.2. Incidental Observations .......................................................................... 525.4.3. Migrants ................................................................................................. 54

5.5. Discussion ..................................................................................................... 546. NATIONAL PARK TOURIST IMPACT ASSESSMENT ........................................... 55

6.1. Introduction .................................................................................................... 556.2. Aims .............................................................................................................. 576.3. Methods ......................................................................................................... 57

6.3.1. Assessment of terrestrial trail condition .................................................. 576.4. Results ........................................................................................................... 58

6.4.1. Assessment of terrestrial trail condition .................................................. 58


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6.5. Discussion ..................................................................................................... 596.5.1. Assessment of terrestrial trail condition .................................................. 59

7. TOURIST IMPACT SURVEY CAO PALMA ......................................................... 617.1. Introduction .................................................................................................... 617.2. Aims .............................................................................................................. 617.3. Methodology .................................................................................................. 617.4. Results ........................................................................................................... 62

7.4.1. Boat Dock Survey .................................................................................. 627.5. Discussion ..................................................................................................... 62

7.5.1. Boat Dock Survey .................................................................................. 628. INCIDENTALS ....................................................................................................... 62

8.1. Introduction .................................................................................................... 628.2. Aims .............................................................................................................. 628.3. Methodology .................................................................................................. 638.4. Results ........................................................................................................... 63

8.4.1. Reptiles .................................................................................................. 638.4.2. Amphibians ............................................................................................ 648.4.3. Mammals (except Primates) ................................................................... 648.4.4. Other Mammals: Primates ...................................................................... 65

8.5. Discussion ..................................................................................................... 679. TEACHING REPORT ............................................................................................. 68

9.1. Introduction .................................................................................................... 689.2. Aims .............................................................................................................. 689.3. Method ........................................................................................................... 68

9.3.1. Expedition Member training .................................................................... 689.3.2. Teaching ................................................................................................ 69

9.4. Results ........................................................................................................... 709.5. Discussion ..................................................................................................... 70

10. Bibliography ........................................................................................................... 7111. APPENDIX ............................................................................................................. 75


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List of 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 200611 ......... 11Figure 2-2 Identified number of Jaguar predated turtles recorded in Tortuguero National

Park. Period: 3rd July 12th September 2006.12Figure 4-1 Seasonal distribution of nests and moons ofC. mydas between June 16th

and September 8th 2006.26Figure 4-2 Seasonal distribution of nests and moons ofE. imbricata, C. caretta and D.

coriacea from June 16

th

until September 8

th

2006...................................................................... .297

Figure 4-3 Spatial distribution ofC. mydas nests and moons between mile 0 and mile

3 1/8 on North Beach of Tortuguero.28

Figure 4-4 Spatial distribution of E. imbricata, C. caretta and D. coriacea nests and

moons between mile 0 and mile 3 1/8 on North Beach of Tortuguero....29

Figure 4-5 Encounter time for all sea turtle species found visiting the North Beach duringnight patrol hours.30Figure 4-6 Nesting orientation of the 4 studied species (n=76) on North Beach between

June 16th and September 8th 2006.31Figure 4-7 Green nest fate recorded during morning and night surveys....33 Figure 4-8 Nest fate of nests marked by triangulation...34Figure 5-1 Total species and surveys on aquatic trails, Cao Chiquero (CC), Cao

Harold (CH) and Cao Palma (CP) ............................................................................... 43

Figure 5-2 Total species and surveys on the Cleared Areas (CA) and Raphia Trail (RT)

study sites ..................................................................................................................... 44


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Figure 5-3 Key species recorded during AM surveys of the Cleared Areas study site ... 44Figure 5-4 Key species recorded during PM surveys of the Cleared Areas study site .. 45Figure 5-5 Key species recorded during AM surveys of the Raphia Trail study site ....... 46 Figure 5-6 Key species recorded during PM surveys of the Raphia Trail study site ....... 47 Figure 5-7 Key species recorded during AM surveys of the Cao Harold aquatic trail site

...................................................................................................................................... 48Figure 5-8 Key species recorded during PM surveys of the Cao Harold aquatic trail ... 49

Figure 5-9 Key species recorded during AM surveys of the Cao Palma aquatic trail ... 50

Figure 5-10 Key species recorded during PM surveys of the Cao Palma aquatic trail . 51

Figure 5-11 Key species recorded during AM surveys of the Cao Chiquero aquatic trail

...................................................................................................................................... 52

Figure 5-12 Migrant species observed during phase 5 in the Cleared Area and Raphia

Trail study sites. ..54Figure 6-1 Change in path width at eleven different study sites on the trail ..59 Figure 8-1 Number of incidental primates recorded around Cao Palma Biological

Station and while traveling on the boat .......................................................................... 66

Figure 8-2 Behaviour frequencies of Incidental primates recorded around Cao Palma

Biological Station and while traveling on the boat .......................................................... 67


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List of Tables

Table 4-1 Tags applied by the Cao Palma Sea Turtle Monitoring Program from 9th of

September until 25th of October 2006... . 31

Table 4-2 Tags removed or destroyed by the Cao Palma Sea Turtle Monitoring

Program from 9th of September until 25th of October 2006 ........................................... 32

Table 4-3 Green mean carapace length, carapace width and clutch size on the North

Beach between June 15th and September 8th 2006 ..................................................... 32

Table 4-4 Summary of excavation results for one Loggerhead nest (Cc), one

Leatherback nest (Dc) and one Green nest (Cm) on North Beach. 35

Table 4-5 Hatchling and emerging success for 53 marked Green turtle nests excavated

from September 9th until December 11th 2006 on North Beach. ................................... 35

Table 4-6 Hatchling and emerging success for 11 unmarked Green turtle nests

excavated from September 9th until December 11th 2006 on North Beach. .................. 36

Table 8-1 Incidental reptiles recorded around Cao Palma Biological Station and while

traveling on the boat ...................................................................................................... 64

Table 8-2 Incidental amphibians recorded around Cao Palma Biological Station and

while traveling on the boat ............................................................................................. 64

Table 8-3 Incidental mammals recorded around Cao Palma Biological Station and while

traveling on the boat ...................................................................................................... 65


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2. JAGUAR PREDATION ON MARINE TURTLES

2.1. Introduction

Tortuguero National Park (TNP) is the most important nesting ground in the western

hemisphere for Green Turtles (Chelonia mydas). In addition to the C. mydas there arealso a significant number of Leatherbacks (Dermochelys coriacea) and the occasional

Hawksbill (Eretmochelys imbricata) and Loggerhead (Caretta caretta) (Trong 2000).

The nesting turtle population has been monitored on the parks beach since the 1950s

and continues to be monitored today by the Caribbean Conservation Corporation (CCC).

Information on Jaguars (Panthera onca) predating on marine turtle is sparse. In TNP,

and many other areas, marine turtle predation by Jaguars has been recorded

sporadically. 82 C. mydas were identified as being predated by Jaguars in Suriname

from 1963-1973. On the same beach in 1980 one Jaguar killed 13 turtles within only a

few days (Autar, 1994). On the Pacific coast of Costa Rica Jaguars have been recorded

preying upon Olive Ridley Turtles (Lepidochelys olivacea), Black Turtles (Chelonia

agassizii), and E. imbricata. This predation upon turtles by Jaguars is not a new

phenomenon but seems to have been increasing in the past 10 years within TNP

(Trong 2000; Magally Castro, pers. comm.) Although, there has been much research

done on turtles in TNP, from 1956 to 1995 there were only two C. mydas recorded to be

killed by a Jaguar, one in 1981 and another in 1984 (Carrillo et al. 1994). Weekly walks

on the beach to record the number of dead turtles killed by Jaguars began in 1997 as

part of the Caribbean Conservation Corporations (CCC) turtle monitoring programme.

The CCC found four dead C. mydas killed by Jaguars in 1997, 25 in 1998, 22 in 1999,

and two Leatherbacks in 1999 (Trong 2000).

Due to a lack of human resources the Costa Rican Ministry of Environment and Energy

(MINAE) invited GVI to continue data collection on Jaguar presence and predation of

marine turtles in TNP. Data collection has now been conducted by GVI since 11 th July

2005. Together with the data previously collected by MINAE, a more comprehensive

understanding of Jaguarimpact on the turtle population of TNP can be developed.


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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 once or twice per week depending on conditions, starting

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

researchers, 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 (one to two nights old)

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

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 (northern 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. It is also noted if the tracks simply

were lost or if there is a clear entrance or exit point from the beach. 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 turtle carcasses killed by Jaguars that have not been previously

recorded. This includes turtle ID number, location (mile marker and GPS coordinates),

species, point of attack, number of nights since kill, parts of turtle eaten, location of

carcass relative to the vegetation, CCL (curved carapace length) and CCW (curved


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carapace width) when possible, whether the turtle is on its front or back and any other

extra comments/observations. For each turtle a photograph must be taken a few meters

from the turtle with your back to the sea. This picture should include background

vegetation to help identify the turtle in the future if necessary. Photographs of anything

else of interest or out of the ordinary should be taken.

2.4. Results

A total of 10 surveys were conducted between 20 October and 12 December with an

average time of 7 hours and 52 minutes. The longest walk was 10 hours and four

minutes and the shortest was 5 hours and 54 minutes. A total of 61 surveys have been

conducted by GVI since 11 July 2005.

During this phase, 28 C. mydas were killed by Jaguars. The number of separate sets of

Jaguar tracks found during this phase was 71 and a total of 2833.5 turtle tracks 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

4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11 11

.5 12 12.5 13 13

.5 14 14.5 15 15

.5 16 16.5 17 17

.5

Mile

Dead Turtles

Turtle Tracks x 10

Jag Tracks

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

Tortuguero National Park. Survey Period: 20 Oct12 Dec, 2006.


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During this phase, all of the turtle carcasses were located between miles five and 16 with

a high concentration between miles 4 4/8 and 8. Jaguar tracks ranged between miles 4

4/8 and 18 with the highest concentration between miles and 8 4/8 and 10 4/8 and then

again between 13 4/8 and 16. The turtle carcasses found within the high Jaguar activity

area make up 32% of the total turtle carcasses found. Figure 2-2 shows the number ofkilled turtles found each week of this phase.

Dead Turtles Found During Phase 064 per Week Killed

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Week 36 Week 37 Week 38 Week 39 Week 40 Week 41 Week 42 Week 43 Week 44 Week 45 Week 46

Week of Year

NumberofDeadTurtles

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

Period: 3rd July 12th September 2006.

Beach conditions this phase made Jaguar track data easier to record. Often there was a

high amount of rain before the walk packing the sand down and making tracks from the

night before or that morning easy to see and follow. However, because of rain during

surveys data collection at times was difficult. On one occasion a walk ended at mile 15

(three miles early) due to rainy conditions.

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

Rangers have reported seeing Jaguars several times over the past couple of months.

On one occasion Jaguar tracks were found on the Gavilan trail very close to Tortuguero.


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On the 22 November a large Jaguar was seen by GVI near mile 14 (N10 24 02.5

W83 25 15.3) during a Camera Trapping survey. It was lying in an old turtle nest for five

minutes then walked into the vegetation once it noticed the surveyors. The Jaguar was

seen again about 15 minutes later when it went quickly into the vegetation once again.

On a separate Camera Trapping survey a dead turtle was found in the vegetation only a

few hours old. The turtle had been attacked on the neck and was dragged five meters

into the forest but not eaten. Five days later the turtle was found to be dragged further

into the vegetation, flipped on its back and presumably eaten by a Jaguar.

2.5. Discussion

Data collected during Phase 064 from early October to late December includes the end

of the C. mydas season. A high amount ofC. mydas tracks were seen on the walks at

the beginning of the phase but numbers fell quickly towards the middle of the phase.

During the last walk only four C. mydas tracks were found. All 28 dead turtles found

were C. mydas. The kills that were very fresh were always found near Jaguar tracks

and many of the turtle carcasses were found in high Jaguar activity areas.

The only animals that are known to kill adult sea turtles are Sharks, Crocodiles, Killer

Whales, and Jaguars (Hirth 1997, Oritz et al. 1997). Because of this any C. mydas

carcasses that showed no sign of being poached were presumed to have been killed bya Jaguar. The majority of the turtles were found in the open area of the beach (54%),

however a high proportion was also found in the vegetation (32%) and the border (14%).

As previously collected data has shown, Jaguars appear to be consuming only a small

percentage of the turtle meat. In the majority of cases it was found that only the neck

was consumed. This method, by which the Jaguars feed off the turtles, is confirmed by

the video footage obtained by the National Park rangers.

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

hypothesis 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

required to replace the total energy expenditure of the kill (Castro,pers. Comm.; Carrillo,

pers. comm.) There were many other potential Jaguar prey or tracks of prey seen on


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the beach during the surveys, such as a White-nosed Coati (Nasua narica), Black River

Turtle (Rhinoclemmys funerea), Spider monkeys ( Ateles geoffroyi), White-faced

Capuchins (Cebus capucinus) Green Iguanas (Iguana iguana), Great Curassows (Crax

rubra), Red Brocket Deer (Mazama americana),Agouti paca, and Tayra (Eira barbara).

Therefore Jaguars may be on the beach in search of any prey species and not turtlesexclusively. Further research on this topic is needed before any conclusions can be

made.

GVI now has over a year of data collected on the predation of turtles by Jaguars. It is

becoming clear through the data that there is an increase in the predation upon turtles. It

is possible that after many months of working on the project the expedition as a whole

has become better at finding turtles deep in the vegetation. However, this phase there

were 28 predated turtles and during this phase last year only 15 predated turtles werefound. GVI will continue to monitor the number of turtles being predated in future

phases.

3. CAMERA TRAPPING

3.1. Introduction

The Jaguar (Panthera onca) is the third largest felid in the world and the largest in all of

North and South America (Silver 2004). Its range spans from southwestern United

States to northern Argentina (Seymour 1989), however, the current range is less than

50% what it was in 1900 (Sanderson et al. 2002b). The Jaguar is an elusive animal that

has been hunted greatly in the past for its pelt. In 1968 alone, more than 13,000 pelts

were imported to the United States (NatureServe 2006). The demand for Jaguar pelts

has since declined but there are still many clashes between the animal and humans.

Jaguars will occasionally kill farm animals and are hunted by farm owners when they are

considered a problem (Nevarro-Serment 2005). Today the major threats to the Jaguar

are illegal hunting, prey depletion, and habitat destruction and fragmentation (Silver2004). Jaguars depend upon a variety of ecosystems and need a wide home-range.

Scientists have now started to focus on a range-wide approach to the conservation of

the species. However in order to aid future conservation initiatives of the species a

greater understanding of Jaguar population dynamics is needed (Sanderson et al.

2002b).


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Very little is known about the population of Jaguars in TNP. The National Park guards

have seen Jaguars on numerous occasions and they are guessing that there are six to

eight individuals currently using the beach. GVI is using photo trapping cameras initially

to identify presence and habits, but in the future they could potentially be used to do a

population study by identifying individuals and using mark/recapture models. Cameratraps have been used before in this way to study tiger (Panthera tigris) populations in

India (Karanth 1995, Karanth & Nichols 1998, 2000, 2002) and to study Jaguar

populations in Central and South America (Silver 2004). We have adopted similar

methods as used by Silver and are currently undertaking field trials.

3.2. Aim

The main aim is to have an estimate of Jaguars using the coastal habitat inside

Tortuguero National Park. In order to do so, we need to identify individual animals.

Specific objectives that can be reached at the same time are 1) to determine the areas

where jaguars are present, 2) to record their hours of activity and habits, 3) to compare

jaguar activity at the different sites along the beach.

3.3. Methodology

3.3.1. Study Site

The beach of TNP is 18 miles long with posts marking every half-mile (the half miles aremarked as 4/8). Tortuguero Village is located at about mile three (the north end of the

beach) and Jalova is located at mile 18 (the south end of the beach). There is a trail

parallel to the beach running from mile 0 to about mile 14 4/8. Along the trail there are

many paths that lead to the beach close to town but get more sparse further south.

Tourists use this trail frequently during the turtle season up to about mile six. During off-

season tourists and local people occasionally use the trail.

3.3.2. General

Cameras are placed in the forest along the edge of the TNP beach. GVI has been

recording data on Jaguar presence on the TNP beach for over a year. The areas of high

activity and known entrance and exit points of Jaguars will be used to assist in selecting

camera sites. There are many things to consider before selecting a camera site. Ideally

the cameras are placed about no more than two miles apart trying to avoid the possibility


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3.3.4. Checking the cameras

The cameras will be checked at least once a week to ensure they still function and to

change film as necessary. Depending on the activity level, this can be done more or less

often. Every time, the team needs to bring extra batteries and a sealed container or bagto carry the role, if needed.

The team needs to keep track of how many trapping nights have passed between the

last time the cameras were checked and the next check. The idea is to have a ratio of

number of pictures taken divided by trapping nights.

When all the film frames are close to being used, the silica gel needs to be cut with the

cutter and the roll needs to be rewound. It should be brought to the station to be

developed and a new film installed in the camera. Make sure the roll is labelled with the

camera location name and date. Once the film has been developed, the information from

the pictures needs to be entered in the data spreadsheet.

3.3.5. Data entering and analysis

Data entering consists of two steps: the data entered after each Camera Walk and the

data to be entered once the film has been developed and the results known.

Data should be entered after each Camera Walk, including:

Date

Name of team leader

Names and location of cameras checked

Number of pictures taken

After the film has been developed, in the same spreadsheet the following data needs to

be entered in additional columns:

Date

Time

Name of team leader

Names and location of cameras checked


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Comments

3.4. Results

In this phase we have set up cameras at nine different sites. Five roles of film have been

developed with 35 photographs of animals. The two species photographed were the

Black Vulture (Coragyps atratus) and the Great Curassow (Crax rubra). We had a total

of 89 trap nights for all of the cameras combined.

Site one was located 425m before mile 6 4/8. Two cameras were placed there because

a dead turtle was found in the vegetation only hours old and it was presumed the Jaguar

would return. The film was removed after two nights and revealed only photos of

vultures. Three days after the film was removed the cameras were found stolen and the

turtle had been dragged ten meters into the vegetation presumably by the jaguar.

The camera at site two, located 170m before 7 4/8, was up for 11 days. It was put up on

the 16th of November and taken down on the 27th of the same month because it was too

close to a human trail. One photo of a Great Curassow was recorded on November 16th.

The camera at site three, located 420m before 4 4/8, was up for 11 days. It was put up

on the 17th of November and taken down on the 28th of November. There were no

photographs of animals.

The camera at site four, located 15m after mile 12, was left up for five days. It was put

up on the 17th of November and taken down on the 22nd. The camera was put at the

edge of the vegetation in the middle of the path. An old predated turtle was on the beach

near the entrance to the path. No animals were photographed.

Camera site five, located 300m before 16 4/8, was up for five days. It was used from the

17th of November through the 22nd then taken down. No animals were photographed.

Camera site six is located 192m after mile 19. The camera was put up on the 22 nd of

November and taken down on the 12th of December. The camera was placed 200m into

the forest facing a trail that runs parallel to the beach.


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The camera at site seven, 450m after 6 4/8, was put up on the 27 th of November and

taken down on the 11th of December. It was placed about five meters into the forest on

an animal trail.

At site eight a camera was put up on the 28th

of November 373m before 14 4/8. thiscamera was taken down on the 12th of December. The camera was placed 10m into the

vegetation directly behind an old dead turtle.

Site nine has had one camera up since December 4 th and it was taken down on the 11th

of December. It was placed five meters after mile six about 18 meters into the

vegetation.

3.5. Discussion

Although no photographs of Jaguars were taken, a great deal was learnt this phase

about site selection and operation of the cameras. We are continuing to develop the

project and will revise our methods before setting up the cameras again. During the next

phase we will set camera stations, although the area covered will be smaller. We will

choose sites less likely to be found by humans. We will also try to camouflage the

cameras and possibly lock them to the tree in some way.

4. SEA TURTLE MONITORING PROGRAMME

4.1. 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 Leatherback turtle

is classified as critically endangered and Green turtles as globally endangered on the

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

and the surrounding areas are continuously developing and thus the need 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


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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 Green turtles and Leatherback turtles on North Beach (the beach just north ofLaguna 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.

4.2. Aim

Based on 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 predationof nests.

The collected data are intended to be used as a basis for the development of a

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

of all sea turtle species during future nesting seasons.

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

4.3. 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.


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4.3.1. Study site

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

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

at the southernmost point until Laguna Cuatro (103756,3N 833225,7W) in thenorth. Although this beach is not located within the TNP boundaries, it is situated within

the Barra del 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 200 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 two 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 pescaprae), Rea-purslane (Sesuvium portulacastrum) and Rush grass

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

(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, bottles, etc.


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4.3.2. Daily track census and nest surveys

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

Green turtles, nesting from June to November, and the occasional Hawksbill and

Loggerhead turtle, both nesting from June to September (Trong et al. 2004). Surveyswere and are conducted every day and night from March 1st until October 31st 2006.

The daily track surveys start at 6:00 am and last until 8:30 am consisting of walking the

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

night before. The day team identifies 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 is 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 are then identified as natural (if

remained in its original state), poached (with at least two 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 is also recorded when encountering dead turtles on the beach. The size, sex, state

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

unnatural death is 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

is recorded and checked against CCC tagging data.

4.3.3. Night surveys

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

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

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

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

During all of this phase only one patrol per night could be carried out.

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 night


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team at any time, except when two teams meet between 00:00 and 00:30, there is a

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

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 is collected: the date, the

time when the track is found, the species, the activity corresponding with a sequence

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 is observed the number of laid eggs including yolkless eggs isrecorded. Any other comments or anomalies observed are noted.

4.3.4. Tagging

Leatherback turtle females are tagged in the membrane located between the tail and the

rear flipper using Monel #49 tags (National Band & Tag Co., Newport, USA). Green,

Hawksbill and Loggerhead turtle females are tagged in the front flippers just before the

primary scale using Inconel #681 tags. Females are only tagged if they lay eggs and

then the tagging takes place while they are 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), are recorded, as well as evidence of trauma or parasites

due to old tags.

4.3.5. Biometric Data

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

using a plastic glove and a manual counter (clicker). Leatherback turtles and in some

cases Green turtles lay both normal and yolkless eggs.

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

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

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

and the average of the three measurements is calculated.


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Minimum Curved Carapace Length (CCLmin): In Leatherback turtles CCLmin is

measured from the beginning of the carapace on the neck, extending along the

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

other species the measurement is 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.

4.3.6. Nest Fate, Nest Survivorship and Hatching success

Samples of nests are marked using triangulation in order to locate the nests five days

after the estimated hatching time or 70 days after the nest was laid for excavation.

Triangulation is conducted during oviposition using three pieces of flagging tape (tags)

which are attached to the vegetation behind the nest. The distance from the center of the

egg chamber to each of these tags is measured to the nearest cm whilst the turtle is

laying eggs. The distance to the most recent high tide line is 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 are used to compensate for the loss of any

points of reference. If one tag is lost it is still possible to locate the nest using the other

two tags.

Marked nests are excavated five days after hatching, whereas if there are no signs of

hatching, excavation takes place five days after the average incubation period for each

of the species. Leatherback turtle nests are therefore excavated 75 days after they had

been laid, while Green, Hawksbill and Loggerhead turtle nests are excavated 70 days

after the date they had been laid. This report includes all nest fate and excavation data

collected until the 11th of December 2006.

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

excavated five days after the first hatchling tracks are encountered.

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 are counted and recorded.


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For all accurately marked and measured nests a nest fate is determined. Nests which

are not marked or measured correctly, or for which more than one reference is lost are

excluded from analysis. The following nest fate categories are applied: hatched,

poached, predated, eroded and flooded. Empty egg chambers are classified as poached

nests. If there is any doubt about the fate of a nest it is categorized as unknown.

During all excavations the bottom depth of nests, which is the depth measured from the

surface to the bottom of the nest after all eggs have been removed, is measured using a

stick and a 1,50 m fiber glass measuring tape.

4.4. Results

Night data from this phase was collected from September 9th until October 25th whereas

morning surveys were carried out until October 31st.

The total numbers of morning and night surveys undertaken were 52 and 47,

respectively.

During daily track census a total of 312 miles were walked in a total of 97 hours and 12

minutes, taking an average of one hour and 52 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 258 3/8 miles and were completed in a total of 193 hours and 20 minutes,

taking an average of four hours and six minutes to walk an average of five miles per

night.


Without taking into consideration the half moons and dead turtles, 29.5% (n=44) of the

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

remaining 70.5% (n=105) were from tracks found but no turtle seen during both nights

patrols and the daily track census. Only 11 turtles were observed doing a half moon.

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

Hawksbill, Loggerhead and Leatherback turtles. A total of 367 tracks were observed,

divided into 149 nests and 218 half moons. The nests were 98.66% Green (n=147) and

1.34% Hawksbill (n=2) whereas no Loggerhead or Leatherback nests were found during


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this phase. Regarding the vertical distribution of Green turtles nesting on the beach

36.54% were seen in the open area (n=19), 36.54% on the border (n=19) and 26.92% in

the vegetation (n=14). (There was no information regarding the vertical position for one

Green turtle). The two Hawksbill nests were both located in the vegetation.

The seasonal distribution of nests and half moons of Green turtles is shown in Figure 4-

1, for Hawksbill turtles in Figure 4-2 respectively.

0

10

20

30

40

50

60

70

80

Sept 9-14 Sept 15-22 Sept 23-30 Oct 1-8 Oct 9-16 Oct 17-24 Oct 25-31

Cm Nests

Cm 1/2 Moons

Figure 4-1. Seasonal distribution of nests and half moons of Green turtles between September 9 th

and October 31st 2006.


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0

0.5

1

1.5

2

2.5

3

3.5

Sept 23-30 Oct 1-8 Oct 9-16

Ei Nests

Ei 1/2Moons

Figure 4-2. Seasonal distribution of nests and half moons of Hawksbill turtles between September

9th and October 31st 2006.

Most Green turtle nests were recorded in September (n=110) which also accounted for

the highest number of half moons (n=172). In October 37 Green turtle nests and 41 half

moons were found on North Beach.

Hawksbill turtles nested in the period from 23rd of September until 16th of Octoberaccounting for a total of two nests and five half moons.

Figure 4-3 demonstrates the spatial distribution of nests and half moons of Green turtles,

while figure 4-4 shows the spatial distribution for Hawksbill turtles.


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0

5

10

15

20

25

30

0 1/8

2/8

3/8

4/8

5/8

6/8

7/8

111/8

12/8

13/8

14/8

15/8

16/8

17/8

221/8

22/8

23/8

24/8

25/8

26/8

27/8

331/8

Beach Location (Mile)

Cm 1/2 Moon

Cm Nest

Figure 4-3. Spatial distribution of nests and half moons of Green turtles between September 9th and

October 31st 2006.

Regarding the spatial distribution of Green turtle nests on North Beach Mile 2 7/8

accounted for the highest number of nests (n=16) followed by Mile 4/8 and 5/8 (both

n=14). Green moons peaked at Mile 5/8 (n=25), followed by 6/8 (n=20) and Mile 1 1/8

(n=18).


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0

0,5

1

1,5

2

2,5

0 1/8

2/8

3/8

4/8

5/8

6/8

7/8

111/8

12/8

13/8

14/8

15/8

16/8

17/8

221/8

22/8

23/8

24/8

25/8

26/8

27/8

331/8

Beach Location (Mile)

Ei 1/2 Moon

Ei Nest

Figure 4-4. Spatial distribution of nests and half moons of Hawksbill turtles between September 9th

and October 31st 2006.

Hawksbill turtle activity was recorded between Mile 2/8 and 1 2/8 (two nests and two

moon) as well as between Mile 2 5/8 and 2 7/8 (3 moons).

4.4.2. Monitoring of female turtles

During the night surveys, 52 female sea turtles were observed during six out of eight

possible nesting activity processes (for three turtles seen no activity information had

been collected). 11.1% were emerging from the sea (n=6), 33.3% were digging the body

pit (n=17), 7.4% were digging the egg chamber (n=4), 13% were in the oviposition

process (n=7), 22.2% were disguising the nest (n=11) and finally, 13% were returning to

the sea (n=7). No dead turtles were found on North Beach during this phase.

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

turtles were registered at 3:00 in the morning (n=1). The peak nesting activity occurred

at 22:30 corresponding to a total of eight turtles encountered at this time during the night

patrols. See figure 4-5.


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0

1

2

3

4

5

6

7

8

9

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

Turtles

Figure 4-5 Encounter time for all sea turtle species (n=52) found visiting the North Beach during

night patrol hours (for three turtles seen no information had been collected regarding the encounter

time).

Out of 32 females for which information was collected regarding the orientation during

oviposition, 28.1% (n=9) were facing West, 25% were orientated towards Northwest

(n=8), 18.7% South (n=6), 9.4% both North and Southwest (each n=3), 6.3% East (n=2)

and 3.1% Northeast (n=1), none facing Southeast (n=0). See figure 4-6.


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0

5

10

15

20

25

30

North

NE

East

SE

South

SW

West

NW

Turtles (%)

Figure 4-6 Nesting orientation of Green and Hawksbill turtles (n=32) recorded on North Beach

between September 9th and October 31st 2006.

4.4.3. Tagging

Of the total females for which information regarding their tags was collected during the

night patrols (n=46), 56.5% were already tagged (n=26), whereas 36.96% (n=17) were

newly tagged out of which 6.52% (n=3) showed old tag holes or old tag notches. The

tags applied by the Cao Palma Sea Turtle Monitoring Program from September 9 th until

October 25th are shown in table 3-1. Numbers of removed or destroyed tags are listed in

table 3-2.

Furthermore one previously tagged and one untagged Hawksbill turtle were encountered

on North Beach during night patrols.

CP0126 CP0179-CP0184 CP0199-CP0202CP0139-CP0143 CP0186-CP0189 CP0205-CP0208CP0145-CP0146 CP0191-CP0192 CP0210-CP0213CP0160-CP0161 CP0194-CP0195

Table 4-1 Tags applied by the Cao Palma Sea Turtle Monitoring Program from 9th of September

until 25th of October 2006.


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88231 removed + recovered CP0196 destroyed - not recoveredCP0185 removed + recovered CP0197 destroyed + recoveredCP0193 destroyed + recovered CP0209 destroyed + recovered

Table 4-2 Tags removed or destroyed by the Cao Palma Sea Turtle Monitoring Program from 9th ofSeptember until 25th of October 2006.

Four tags with the numbers 96968, 96969,104480 and 105163 were given to the station

from turtles which had been killed in San Francisco.

A total of five Green turtles nested twice on North beach from 9th of September until 25th

of October 2006. For three turtles the inter-nesting interval was an average of nine days

long while two turtles nested an average of 22.5 days apart.

4.4.4. Biometric data

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

Green turtles for which this information could be collected is shown in the Table 3-3. The

mean carapace length of newly tagged individuals with no evidence of previous tags

(OTH or OTN) was 103.1 cm (n=17), whereas the mean carapace width was 92.86 cm

(n=17). Newly tagged Greens with old tag holes or old tag notches had a mean

carapace length of 104.7 cm (n=3) and a mean carapace width of 96.29 cm (n=3).

Previously tagged Greens averaged at a carapace length of 106.2 cm (n=17) and a

carapace width of 96.53 cm (n=3.08).The average number of fertile eggs was 116.1 for

newly tagged Green females (n=12) with no signs of previous tagging and 117 for newly

tagged Greens with old tag holes or old tag notches (n=3). Previously tagged Greens

laid an average number of 98.13 eggs per clutch (n=9).

Green turtlesCCL min (cm) CCW max (cm) Number of Eggs

n x nx

n x

Newly tagged Green no OTH/OTN 17 103.1 4.17 17 92.86 3.5 12 116.1 19.58Newly tagged Green with OTH/OTN 3 104.7 0.73 3 96.29 3.57 2 117 36.1

Previously tagged Green17 106.2 2.81 16 96.53 3.08

998.13

Table 4-3. Green turtle mean carapace length, carapace width and clutch size on North Beach from

9th of September until 25th of October 2006.


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One previously tagged Hawksbill turtle was encountered doing a half moon during the

study period. No data could be collected regarding size or number of eggs.

4.4.5. Turtle disease or injuries

Disease and injury related information was not analyzed for this phase.

4.4.6. Monitoring of nests

Out of 126 nests, for which a nest fate was determined during night and morning surveys

45.24% seemed to be left in their natural state without any signs of poaching, erosion or

predation (n=57). Based on at least two evidences such as human foot prints, stick

marks, flies, egg shells and/or an exposed egg chamber, the remaining 54.76% (n=69)

of nests were classified as poached, two of which were Hawksbill turtle nests while 67were Green turtle nests. See figure 4-7.

45%

55%

natural nests

poached nests

Figure 4-7 Nest fate recorded during morning and night surveys on North Beach from 9th of

September until 25th of October 2006.


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4.4.7. Nest Fate of nests marked by triangulation

A total of 62 triangulated and marked nests were due to be dug up within the time frame

analyzed in this report from the 9 th of September until the 11th of December 2006. Nine

nests could not be found because of inaccurate measurements (n=2) or lost tags (n=7),these nests were excluded from analysis. 53 nests were located using the

measurements taken, out of which 64.15% (n=34) of nests were empty (some nests

contained one to a few eggs or eggshells) and therefore classified as poached. 32.08%

of nests (n=17) had hatched while 3.77% (n=2) of nests contained the full clutch of eggs

but did not hatch, both of the latter were excavated. See table 4-4 for a summary of

excavation results and figure 4-8 for nest fate of marked nests.

32%

64%

4%

Hatched and Excavated

Poached

Eggs present but did not hatch

Figure 4-8. Nest fate results of marked nests from September 9th until December 11th 2006.

4.4.8. Excavation Results, Hatching and Emerging success

During morning patrols from September 10th until October 31st 2006 a total of 12 sets of

hatchling tracks were found on North Beach for 11 of which the position of the nest could

be located. These 11 Green turtle nests, all of which had not been triangulated, were


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excavated a minimum of five days after the tracks had been encountered and the data

collected is summarized in Table 4-5.

Out of 62 nests marked by triangulation, 53 could be located using the measurements

and reference points taken. 19 of these nests contained a full clutch of eggs and theircontent was excavated and analyzed. See Table 4-4 for a summary of the data recorded

during excavations of all nests, unmarked and marked.

# ofnests

AliveHatchlings

DeadHatchlings

Shells>50%

YolklessEggs

UnhatchedwithoutEmbryo

Unhatchedwith Embryo

Depredated UnknownTotalEggs

30 6 3 2898 9 111 104 373 76 3562

Table 4-4. Summary of excavation results for 30 Green turtle nests on North Beach from September

9th until December 11th 2006.

For 23 nests the bottom depth of the egg chamber was measured during the nest

excavations. The calculated average nest depth accounted for 67.57 cm (n=23).

The incubation period could not be calculated as none of the marked nests was

observed hatching.

See table 4-5 for hatching and emergence success of the 53 marked nests excavated on

North Beach.

n Fate Eggs total Shells total Hatching

success (%)

Emerging

success

(%)

17 hatched 2006 1823 90.89 90.58

34 poached 3712 0 0 0

2 unhatched 283 0 0 0

53 Total 6001 1823 30.38 30.28

Table 4-5. Hatching and emerging success for 53 marked Green turtle nests excavated from

September 9th until December 11th 2006 on North Beach. Note: For nests of which the number of

eggs laid was unknown, the average number of eggs per clutch (x = 120) was used to calculate

hatching and emergence success.


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Hatching and emerging success for marked hatched nests were almost equal at 90.89%

and 90.58% (n=17) respectively. Overall, triangulated nests accounted for 30.38%

hatching and 30.28% (n=53) success.

Table 4-6 shows hatching and emerging success for 11 nests which were observedhatching during morning and night patrols. As the number of eggs is unknown for those

nests, the average clutch size of 120 eggs was used for analysis.

n Fate Eggs total Shells total Hatching

success (%)

Emerging

success (%)

11 Hatched 1320 1075 81.44 81.21

Table 4-6. Hatching and emerging success for 11 unmarked Green turtle nests excavated from

September 9th until December 11th 2006 on North Beach.

The 11 nests found hatching reached a hatching success of 81.44% and an emerging

success of 81.21%.

4.5. Discussion


The study period from September 9th until October 31st 2006 reflects two months of the

Green turtle nesting season which on the Caribbean coast of Costa Rica ranges fromJune to November. Thus this report does not represent the entire Green turtle nesting

season.

The seasonal distribution of Green turtle tracks shows September as a month of high

nesting activity with 110 nests recorded from September 9 th until September 30th 2006.

October reflects the end of the nesting season with a comparatively low nesting activity

resulting in a total number of 37 nests from October 1st to October 31st 2006.

The only other sea turtle species visiting North Beach during this phase was the

Hawksbill turtle. Seven tracks resulted in two nests and five half moons, the last track of

the season being encountered on October 16th 2006.

Regarding the spatial distribution of sea turtle nests on North beach during the study

period, Green turtles preferred the following sectors: Mile 4/8, Mile 5/8, Mile 1 2/8 and


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intermediate size, their measurements lying in between the CCL and CCW

measurements recorded for the other two turtle categories.

Possibly these results are the outcome of the continuous tagging effort throughout the

Green turtle nesting season increasing the number of tagged re-nesting turtles. This isalso reflected in the overall higher percentage of previously tagged turtles during this

study period (56.5%) compared to the previous phase (44%). The smallest size of newly

tagged turtles without OTN or OTH indicates that these turtles might be neophytes in

their first year of nesting.

4.5.4. Monitoring of nests

Illegal poaching of sea turtle nests was recorded throughout the entire study period.

During beach patrols a minimum of 54.76% of nests were classified as poached

including both of two Hawksbill nests. Compared to 64.15% of poaching of marked nests

by triangulation, the above numbers underestimate the actual poaching rate.

The results of this study period show that the accuracy of triangulation measurements

has improved throughout the sea turtle nesting season, whereas the loss or removal of

triangulation tags seems to be an ongoing problem.

Nests of critically endangered Hawksbill turtles need to be protected by all means,

therefore nest protection measures such as nest relocations should be implemented in

future nesting seasons.

Regarding the globally endangered Green turtles, North Beach receives less than 1 % of

the Tortuguero Green turtle population of nesting females. Their peak nesting occurs on

Tortuguero Beach, where estimated nest numbers range from about 40,000 to about

160,000 nests per season on 23 miles of beach from the Tortuguero River mouth to the

Jalova lagoon. Green turtle 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 with collaborating with local authorities

should hopefully help to decrease poaching of adult turtles and sea turtle eggs. The


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implementation of a sustainable sea turtle conservation program on North Beach should

be aimed for as soon as possible.

4.5.5. Excavation results, hatching and emerging success

The hatching and emerging success of hatched, marked nests recorded on North Beach

is high at 90.89% and 90.58% (n=17) respectively. These numbers are higher than

those recorded for undisturbed, marked nests excavated on Tortuguero Beach by the

CCC (Unpublished Report on the 2005 Green turtle program by the Caribbean

Conservation Corporation) with 82.8% hatching and 80.5% emerging success (n=151).

Regarding hatching and emerging success of 11 unmarked nests observed hatching, the

obtained numbers of 81.44% and 81.21% are closer to the results of Tortuguero Beach

than to the success rates of marked, hatched nests on North Beach.

The overall hatching and emerging success on North Beach is extremely low due to a

high number of poached nests with 30.38% and 30.28% respectively (n=53). Compared

to an overall hatching success of 70.7% and an overall emerging success of 68.1%

recorded on Tortuguero Beach by the CCC, the success rates of sea turtle nests on

North Beach are preoccupying. These results should be a strong enough reason to call

for protective measures, e.g. patrolling of North Beach, by the local authorities during

future sea turtle nesting seasons.

5. EBCP RESIDENT BIRD PROJECT1

5.1. 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 also the largest nesting

colony for the endangered Green Turtle (Chelonia mydas). Because of the geographical

1 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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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 remainsto 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 monitoring

program 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 several different habitats using area

searches, point counts.

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.

5.2. 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?

5.3. 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:


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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.

5.3.1. Point Counts

A point countsurvey records all species seen or heard in a 10 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.

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 stations are not left during this period unless it aids in the identification of a bird.

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 behavior

Examples of behaviors which are recorded include: courtship displays, nest building,

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

behaviors that are strongly correlated with probable or confirmed breeding are recorded.


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5.3.2. 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

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

subadults/ adults

Any notes on breeding plumage or behaviour

5.3.3. 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 as

rare or vagrant in the Widdowson and Widdowson Tortuguero species checklist 2004

were recorded.

5.4. Results

5.4.1. Survey Data

During Phase 064 a total of 58 RBP surveys were undertaken. Of these 10 were

undertaken on the Cleared Areas study site (6 AM surveys and 4 PM surveys), 20 were

undertaken on the Raphia Trail (10 AM surveys and 10 PM surveys), eight were

undertaken on the Cao Palma (5 AM surveys and 3 PM surveys) and on the Aquatic


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0

10

20

30

40

50

60

70

80

90

CA RT

N Surveys

N Species

Figure 5-2 Total species and surveys on the Cleared Areas (CA) and Raphia Trail (RT) study sites

Cleared Areas AM Surveys

0

10

20

30

40

50

60

70

80

BaltimoreOriole

Blackburnian

Warbler

Black-crown

edTityra

BlueG

rosbeak

Brown-cappedTyrannulet

Buff-throated

Saltator

Gray-cappedFlycatcher

LaughingFalcon

LineatedWoo

dpecker

MagnificentFrigatebird

NorthernBarred-Woodcreeper

Pink-billedSeed-Finch

Purple-crown

edFairy

Red-ey

edVireo

RoadsideHawk

Rose-breastedG

rosbeak

Short-billedPigeon

Streak-headedWoodcreeper

Stripe-breastedWren

Stripe-throate

dHermit

SwainsonsThrush

TropicalPewee

Violet-crownedWoo

dnymph

White-breastedWood-Wren

White-fronted

nunbird

Yellow-belliedElaenia

Yellow-marginedFlycatcher

Gray-cheekedThrush

MaskedTityra

PeregrineFalcon

RingedKingfisher

Bright-rump

edAttila

SocialFlycatcher

Bare-throatedTig

er-Heron

Thick-billedSeed-Finch

White-necked

Jacobin

Broad-wingedHawk

SquirrelCuckoo

Cinnamon

Becard

White-crowne

dParrot

Barn

Swallow

White-ringedflycatcher

Yellow-oliveF

lycatcher

Scarlet

Tanager

Slaty-tailedTrogon

Black-cowledOriole

Yellow

Warbler

Purple-throatedFruitcrow

Long-billedHermit

Passerini's

Tanager

BlackVulture

Summer

Tanager

Black-cheekedWoo

dpecker

BayWren

Keel-billed

Toucan

Bronz

yHermit

TurkeyVulture

Olive-backedE

uphonia

GreatCrestedFlycatcher

Boat-billedFlycatcher

White-collared

Manakin

CommonTody-Flycatcher

Golden-hooded

Tanager

MontezumaOro

pendola

Black-mandibled

Toucan

Olive-throatedParakeet

Rufous-tailedHummingbird

Tropical

Kingbird

LesserGreenlet

Palm

Tanager

Blue-gray

Tanager

HouseWren

Chestnut-sided

Warbler

GreatK

iskadee

Black-striped

Sparrow

Clay-coloredRobin

Blue-blackG

rassquit

EasternWood-Pewee

CollaredAracari

VariableSeedeater

Figure 5-3 Key species recorded during AM surveys of the Cleared Areas study site


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For the Cleared Areas AM survey the top five species were: Variable Seedeater

(Sporophila americana), Collared Aracari (Pteroglossus torquatus), Eastern Wood-

Pewee (Contopus virens) and equal fifth were Golden-hooded Tanager (Tangara

larvata), Clay-colored Robin (Turdus grayi) and Blue-black Grassquit (Volatinia jacarina).

The rare species observed during the Cleared Areas AM survey were: Yellow-margined

Flycatcher (Tolmomyias assimilis), Black-crowned Tityra (Tityra inquisitor), Purple-

crowned Fairy (Heliothryx barroti) and Roadside Hawk (Buteo magnirostris).

Cleared Areas PM Surveys

0

2

4

6

8

10

12

14

BayWren

BlackVulture

Black-stripedSparrow

Blu

e-grayTanager

GreatCrestedFlycatcher

LesserGreenlet

Lo

ng-billedHermit

MaskedTityra

NorthernBarre

d-Woodcreeper

NorthernWaterthrush

Olive-backedEuphonia


Sla

ty-tailedTrogon

Stripe-throatedHermit

TurkeyVulture

Blue-blackGrassquit

Pas

serini'sTanager

SquirrelCuckoo

Streak-headedWoodcreeper

T

ropicalKingbird

White-crownedParrot

Yellow-cro

wnedEuphonia

White-collaredManakin

Red-c

appedManakin

ScarletTanager

Black-cowledOriole

Boat-billedFlycatcher

Black-cheek

edWoodpecker

BaltimoreOriole

Cla

y-coloredRobin

GreatKiskadee

Golden-hoodedTanager

Montezu

maOropendola

EasternWood-Pewee

VariableSeedeater

Figure 5-4 Key species recorded during PM surveys of the Cleared Areas study site

For the PM survey the top five species were: Variable Seedeater (Sporophila

americana), Eastern Wood-Pewee (Contopus virens), Montezuma Oropendola

(Psarocolius montezuma), Great Kiskadee (Pitangus sulphuratus) and Golden-hooded

Tanager (Tangara larvata).

The rare species observed during the Cleared Areas PM survey were Yellow-crowned

Euphonia (Euphonia luteicapilla).


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Raphia Trail AM Surveys

0

2

4

6

8

10

12

14

Blue-grayTanager

Chestnut-mandibledtoucan

Greattinamou

P

rothonotaryWarbler


RingedKingfisher

SpottedWoodcreeper

Stripe-throatedHermit

TropicalPewee

TurkeyVulture

Wedge-billedWoodcreeper

Clay-coloredRobin

Golden-crownedSpadebill

BayWren

Plain-brownWoodcreeper

BrownJay

R

ed-cappedManakin

Red-eyedVireo

Ru

fescentTiger-Heron

CinnamonWoodpecker

W

hite-crownedParrot

WoodThrush

Y

ellow-throatedVireo

NorthernBarred-

Olive-throatedparakeet

Gray-neckedWood-Rail

S

tripe-breastedWren

GreatBlueHeron

GreenIbis

Slaty-tailedTrogon

Check

er-throatedAntwren

Violet-crownedWoodnymph

Bright-rumpedattila

Wes

ternSlaty-Antshrike

Yellow-

marginedFlycatcher

Montezumaoropendola

BicoloredAntbird

Che

stnut-sidedWarbler

Grea

tCrestedFlycatcher

Brown-cappedTyrannulet

Long-billedHermit

MealyParrot

White-BreastedWood-Wren

White-flankedAntwren

EasternWood-Pewee

Chestnut-backedantbird

White-CollaredManakin

Olive-backedeuphonia

CollaredAracari

LesserGreenlet

Figure 5-5 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), Collared Aracari (Pteroglossus torquatus), Olive-backed

Euphonia (Euphonia gouldi), White-Collared Manakin (Manacus candei) and equal fifth

Chestnut-bac

phase 6 064 science report final

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