Phase 4 Science Report Final

8/14/2019 Phase 4 Science Report Final

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GVI Costa Rica Expedition 062 Report

(Phase 4)

10th April 18th June 2006


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GVI Costa Rica Expedition 062 (Phase 4) Report

10th April 18th June 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).

26th June 2006

Produced byBritt Larsen, Expedition LeaderLydia Chaparro, Science Officer

Nicole Evans, Community Liaison OfficerJames Lewis, Science Officer

Julie Jackson, InternAlec Gibbson, Intern

And

Ariane Tempier Expedition MemberAnthony Schultz Expedition MemberBrian Jenkins Expedition MemberJoanna Banks Expedition MemberSuzanne Byrne

Expedition MemberEmma Stillmann Expedition MemberAngus Davidson Expedition MemberSunil Sharma Expedition MemberJames Guilder Expedition MemberAlexander Horn Expedition MemberLisa Unsworth Expedition MemberKevin Middleton Expedition MemberDominic Greves Expedition MemberCaitlin Reynolds Expedition MemberElliott Woodward Expedition MemberKatie Huskey Expedition Member

Kelly Ammon Expedition MemberMary Wagner Expedition MemberMegan Behles Expedition MemberNatalie Perini Expedition MemberSarah Itoh Expedition MemberTiffany Burtch Expedition Member

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
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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1. EXECUTIVE SUMMARY

The fourth 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 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 4:

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

English language lessons (collaboration with the San Francisco community)

Inter-cambio with staff from Cabinas Vista al Mar and the Tortuguero National

Park staff at Cuatro Esquinas

Tourist impact assessment on Cao Palma canal in addition to and in comparison

with the tourist impact assessment conducted in Tortuguero National Park

1.1. Introduction

The Coastal Rainforest Conservation Expedition at the Biological Station Cao

Palma in Tortuguero, Costa Rica has now completed its fourth phase (4 x 10 weeks).

The expedition to date has assisted in collecting a substantial amount of scientificdata. 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 in (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 ....................................................................................... i

1.1.

Introduction.................................................................................................... i

Contents ................................................................................................................... iiTables..................................................................................................................... viiFigures................................................................................................................... viii

2. JAGUAR PREDATION ON MARINE TURTLES.................................................102.1. Introduction................................................................................................. 102.2. Aim ............................................................................................................. 112.3. Methodology............................................................................................... 112.4. Results ....................................................................................................... 12

2.5.

Discussion.................................................................................................. 14

3. MARINE TURTLE MONITORING PROGRAMME..............................................163.1. Introduction................................................................................................. 163.2. Aim ............................................................................................................. 173.3. Methodology............................................................................................... 17

3.3.1. Study site............................................................................................ 173.3.2. Daily track census and nest surveys ..................................................183.3.3. Night surveys...................................................................................... 193.3.4. Tagging............................................................................................... 20

3.3.5.

Biometric Data.................................................................................... 20


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3.3.6. Turtle disease or injuries .................................................................... 213.3.7. Nest Survivorship and Hatchling success ..........................................21

3.3.8.

Physical Data...................................................................................... 21

3.3.9. Human impact data ............................................................................ 213.4. Results ....................................................................................................... 22

3.4.1. Daily track census and nest surveys ..................................................223.4.2. Monitoring of nests ............................................................................. 243.4.3. Monitoring of female turtles ................................................................ 253.4.4. Tagging............................................................................................... 263.4.5. Biometric data..................................................................................... 273.4.6. Turtle disease or injuries .................................................................... 29

3.4.7.

Nest survivorship and hatchling success............................................30

3.4.8. Human impact data ............................................................................ 303.5. Discussion.................................................................................................. 31

3.5.1. Daily track census and nest surveys ..................................................313.5.2. Monitoring of nests ............................................................................. 313.5.3. Monitoring of female turtles ................................................................ 333.5.4. Tagging............................................................................................... 333.5.5. Biometric data..................................................................................... 333.5.6. Turtle disease or injuries .................................................................... 34

3.5.7.

Nest suvivorship and hatchling success.............................................34


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3.5.8. Human Impact Data............................................................................ 354. EBCP RESIDENT BIRD PROJECT.................................................................... 36

4.1.

Introduction................................................................................................. 36

4.2. Aim ............................................................................................................. 374.3. Method ....................................................................................................... 37

4.3.1. Point Counts....................................................................................... 374.3.2. Area Searches.................................................................................... 384.3.3. Incidental Observations...................................................................... 39

4.4. Results ....................................................................................................... 404.4.1. Survey Data........................................................................................ 404.4.2. Incidental Observations...................................................................... 44

4.5.

Discussion.................................................................................................. 45

5. NATIONAL PARK TOURIST IMPACT ASSESSMENT ......................................475.1. Introduction................................................................................................. 475.2. Aims ........................................................................................................... 505.3. Methods...................................................................................................... 50

5.3.1. Aquatic Trails...................................................................................... 505.3.2. Terrestrial Trail ................................................................................... 525.3.3. Strawberry Poison Dart Frog transects ..............................................525.3.4. Assessment of visitor use of aquatic trails within the National Park...53

5.3.5.

Assessment of terrestrial trail condition..............................................53


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5.4. Results ....................................................................................................... 545.4.1. Aquatic Trails...................................................................................... 54

5.4.2.

Terrestrial Trail ................................................................................... 58

5.4.3. Strawberry Poison Dart Frog (Dendrobates pumilio) Transects.........595.4.4. Assessment of visitor use of aquatic trails within the National Park...595.4.5. Assessment of terrestrial trail condition..............................................61

5.5. Discussion.................................................................................................. 615.5.1. Aquatic Trails...................................................................................... 615.5.2. Terrestrial Trails.................................................................................. 655.5.3. Strawberry Poison Dart Frog Transects .............................................665.5.4. Assessment of visitor use of aquatic trails within the National Park...66

5.5.5.

Assessment of terrestrial trail condition..............................................67

5.5.6. Summary included in report to National Park.....................................676. TOURIST IMPACT SURVEY CAO PALMA .....................................................68

6.1. Introduction................................................................................................. 686.2. Aims ........................................................................................................... 686.3. Methods...................................................................................................... 69

6.3.1. Aquatic Trails...................................................................................... 696.3.2. Boat Dock Survey............................................................................... 69

6.4. Results ....................................................................................................... 70

6.4.1.

Aquatic Trails...................................................................................... 70


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6.4.2. Boat Dock Survey............................................................................... 706.5. Discussion.................................................................................................. 70

6.5.1.

Aquatic Trails...................................................................................... 70

6.5.2. Boat Dock Survey............................................................................... 717. COMMUNITY WORK.......................................................................................... 71

7.1. Introduction................................................................................................. 717.2. Aims ........................................................................................................... 717.3. Method ....................................................................................................... 72

7.3.1. Expedition Member training................................................................ 727.3.2. Teaching............................................................................................. 72

7.4. Results ....................................................................................................... 73

7.5.

Discussion.................................................................................................. 73

8. Bibliography ........................................................................................................ 749. APPENDIX.......................................................................................................... 78


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Tables

Table 3-1. Number of nests, half moons and horizontal distribution of nests from the

North Beach22

Table 3-2. Tags applied by Cao Palma Sea Turtle Monitoring Programme from 1 st

March to 15th June 2006...26

Table 3-3. Leatherback mean carapace length, carapace width and clutch size on the

North Beach27

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

Beach..28

Table 3-5. Hawksbill mean carapace length, carapace width and clutch size on the

North Beach28

Table 3-6. Loggerhead mean carapace length, carapace width and clutch size on the

North Beach29

Table 3-7. Mean and range carapace length and width and clutch size of leatherback

turtles found more than once on the North Beach29

Table 4-1. Incidental recordings of rare species observed during phase 4.44

Table 5-1 Number of the most common key species observed during each study

phase based on Cao location54

Table 5-2 Adjusted number of the most common key species observed during each

study phase based on Cao location.55

Table 5-3 Records collected from night survey of the terrestrial trial during phase

459

Table 5-4 Data collected during Phase 4 on the total number of boats recorded

entering Tortuguero National Park..60


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Figures

Figure 2-1. Beach distribution of Jaguar tracks, turtle tracks, and dead turtles alongthe 14.5 miles in Tortuguero National Park. .13

Figure 2-2. Date distribution of Jaguar tracks, dead turtles, and total turtle tracks in

Tortuguero National Park.14

Figure 3-1. A) Seasonal nesting distribution of leatherback turtles. B) Seasonal

nesting distribution of green, hawksbill and loggerhead turtles on the North

Beach...23

Figure 3-2. A) Spatial nesting distribution of leatherback turtles. B) Spatial nesting

distribution of green, hawksbill and loggerhead turtles on the North Beach23

Figure 3-3. Destiny of the nests (all species) on the North Beach24

Figure 3-4. Temporal activity distribution of the 4 studied species (error bars 5%) on

the North Beach.25

Figure 3-5. Nesting orientation of the 4 studied species (n = 27) on the North Beach

between March 1st and June 15th 2006..26

Figure 3-6. Distribution of the injuries presents on the turtles checked on the North

Beach...30

Figure 4-1. Distrubution of survey periods and study sites during Phase 4.40

Figure 4-2. Key species recorded during surveys of the Cleared Areas studysite41

Figure 4-3. Key species recorded during surveys of the Cao Palma study site42

Figure 4-4. Key species recorded during surveys of the Cerro Tortuguero study

site43

Figure 4-5. Key species recorded during surveys of the North Beach study site44


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Figure 5-1. Variation in most common key species recorded based on study phase in

all Caos.56

Figure 5-2. Variation in most common key species recorded based on study phase

and Access (AC) Cao only.57

Figure 5-3 Variation in most common key species recorded based on study phase

and Cao (Harold (CH) and Chiquero (CC) only)57

Figure 5-4 Variation in observed records of Little Blue Heron (Egreta Caerulea)

based on study phase within all study areas.58

Figure 5-5 Data collected during Phase 4 on the total number of tourist boats

recorded entering the National Park...60

Figure 5-6 Data collected during Phase 4 on the total number boats recorded

entering the National Park61

Figure 6-1. Key species recorded during surveys of the Cao Palma study site70


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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 Green Turtles thereare also 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 beach of the

park since the 1950s and continues to be monitored today by the Caribbean

Conservation Corporation (CCC).

The National Park is also home to the Jaguar (Panthera onca) which is the largest felid

in the western hemisphere (Silver et al., 2004) measuring up to two meters in length and

weighing about 120 kg. The Jaguar population is threatened in main due to hunting,

habitat destruction and fragmentation. This fragmentation can result in populations

becoming so isolated they are considered severely endangered (Madellin et al., in

press). The range of Jaguars stretches from southern USA to Argentinean Patagonia

and has been reduced by 50% since 1900 (Sanderson et al., 2002). The range of an

individual Jaguar is estimated to be as low as 1 individual per 11km2 (Silver et al., 2004)

to as high as 1 individual per 64km2 (Rabinowitz & Nottingham, 1986). Jaguar preys on

a variety of species including White-lipped Peccary (Dicotyles pecari), White-tailed Deer

(Odocoileus virginianus), Bairds Tapir (Tapirus bairdii), Capybara (Hydrochaeris

hydrochaeris), turtles, and Spectacled Caimen (Caiman crocodiles) (Oliveira, 1994).

Information on Jaguar predating on sea turtle is sparse. In TNP, and many other areas,

marine turtle predation by Jaguar has been recorded sporadically. Eighty-two C. mydas

were identified as being predated by Jaguar 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 Jaguar have been recorded preying upon Olive Ridley

Turtles (Lepidochelys olivacea), Black Turtles (Chelonia agassizii), and Hawksbills E.

imbricate. This predation upon turtles by Jaguar 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. mydass recorded to be killed by Jaguar (in 1981

and 1984) (Carrillo et al., 1994). Weekly walks on the beach to record the number of


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dead turtles killed by Jaguar began in 1997, as part of the turtle monitoring programme,

and continued until 1999. Four dead C. mydaswere found killed by Jaguarin 1997, 25

in 1998, 22 in 1999, and two Leatherbacks in 1999 (Trong, 2000). Though there is

much more to learn about the predation of Jaguar on marine turtles some interesting

data has been collected to date. Jaguarshave been recorded killing marine turtles inthe open area of the beach and occasionally dragging the turtle to the vegetation. There

was one instance where a turtle was dragged 100 meters into the forest. In most cases

a very small proportion of the turtle was eaten, in many examples only the neck muscle

was consumed (Trong, 2000). Trong (2000) also states that there was evidence of

Jaguar approaching nesting turtles yet not attacking them. Theories for this behaviour

were not put forward, however ongoing field work undertaken by GVI may help to gain

an understanding of Jaguarprey selection within TNP.

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 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.

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 mile stretch of beach from the entrance of

Tortuguero National Park (mile 3) south to Jalova lagoon (mile 18). At least four

surveyors conduct the survey once per week, 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.


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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 peek of C. mydas season these numbers cannot be

exact because of the high numbers of turtle tracks that are seen on the beach.

When fresh Jaguar tracks are encountered, the right hind foot is photographed and the

length and width of the track are measured. The direction of the track (north or south)

and location (mile marker and GPS coordinates) are also 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 surveysare 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 extra comments/observations. Photographs of

particular features may be taken.

2.4. Results

A total of 9 full surveys were conducted between 19 April and 14 June with an average

time of 8 hours and 6 minutes. A total of 40 surveys have been conducted by GVI since

11 July 2005.

During Phase 4, 18 C. mydaswere killed by Jaguars. The number of separate sets of

Jaguar tracks found during this phase was 35. A total of 455 C. mydastracks and 170 D.

coriaceatracks were recorded in eight of the nine surveys1.

11 There was no distinction made between Green and Leatherback tracks on one Jaguar survey.


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0

5

10

15

20

25

30

35

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Mile4

Mile5

Mile6

Mile7

Mile8

Mile9

Mile10

Mile11

Mile12

Mile13

Mile14

Mile15

Mile16

Mile17

Mile18

M ile M arker

Total Jaguar

TracksTot al Turtle

TracksDead Turtles

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

Tortuguero National Park. Period: 19 April14 June 2006.

During this phase, all of the turtle carcasses were located between miles 6 and 15

with a high concentration between miles 10 and 13 . The area between miles 9 and 10 contained 4 turtle carcasses and the area between miles 12 and 14 contained 6

turtle carcasses. The highest concentration of Jaguar tracks was between miles 9 and

10 and again between miles 12 and 14. The turtle carcasses found within the high

Jaguar activity area make up 56% of the total turtle carcasses found. Figure 2-1 shows

the location of turtle tracks, Jaguar tracks, and turtle carcasses per half mile. Figure 2-2

shows the number of turtle tracks, Jaguar tracks, and turtle carcasses for each walk.


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0

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Wk 1

(19/04/06)

Wk 2

(26/04/06)

Wk 3

(03/05/06)

Wk 4

(10/05/06)

Wk 5

(19/05/06)

Wk 6

(24/05/06)

Wk 7

(31/05/06)

Wk 8

(07/06/06)

Wk 9

(14/06/06)

Numb

erofP.onca

tracksandnumberofdeadturt

les

0

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40

60

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Numberofturtletracks

P.onca Tracks

Dead Turtles

Turtle Tracks

Figure 2-2. Date distribution of Jaguar tracks, dead turtles, and total turtle tracks in Tortuguero

National Park. Period: 19 April14 June 2006.

2.5. Discussion

Data collected during Phase 4 from mid-April to mid-June includes part of the D.

coriaceaseason and the beginning of the C. mydasseason. D. coriaceaand C. mydas

tracks were seen on all walks throughout the phase. All 18 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. All of the turtle carcasses

were found between miles 6 and 15 which could in part be due to the fact that there isless human presence in this area..

All 18 C. mydascarcasses found were presumed to be killed by Jaguar. Most of the

turtles were found in the vegetation having been dragged by theJaguarfrom the beach.

This varies from the findings of the patrols done from 1997 to 1999 when most turtles


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found were in the open area. One potential reason for this is that there may be more

people walking the beach now forcing the Jaguars to retreat into the vegetation.

However, the surveys conducted in the past were focused mainly on recording turtle

tracks. Therefore the team may have missed some turtles that were located in the

vegetation whereas the main focus of the GVI surveys is to record how many turtles arebeing predated on by Jaguar each year. Because of this there is a conscious effort by

the team to walk very close to the vegetation to avoid missing any dead turtles.

Supporting previously collected data the fresh kills show that only a small part of the

turtles are eaten by Jaguars including the neck muscles and part of the internal organs.

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

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

are easy to approach and kill (Schaller, 1972). It may also be that Jaguars exert such asmall amount of energy killing turtles that not much meat is required to replace the total

energy expenditure of the kill. 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. Therefore Jaguars 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.

The last walk of Phase 4 occurred on the 14th of June which is only the beginning of the

C. mydasseason. From January 2006 to the last walk in June there have been a total of

20 recorded dead turtles killed by Jaguar. It is assumed that over the next three or four

months, until the end of C. mydasseason, more turtles killed by Jaguar will be found.

The number of turtle carcasses will most likely be significantly higher than the numbers

found in 1998 and 1999. Only 25 C. mydaswere 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 increasing in the Park, pushing more Jaguarsonto 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. It is also possible that

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

necessity (Trong, 2000).


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In all surveys, pictures and measurements were taken of the back right print of the

Jaguar. The intention was to be able to identify individual Jaguars through a computer

program that analyses 48 different measurements (Miller, 2001). It has since been

confirmed that distinction of Jaguar using this program is not possible (C. Miller, pers.

comm.)

Surveys will continue to be conducted throughout the C. mydasseason allowing for a

better analysis of an entire year which will provide much valuable data on the predation

of marine 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. MARINE 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 IUCNRed List (IUCN, 2003). In addition to the general decline in sea turtles, Tortuguero and

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

and conservation of the 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 this protection is contributing to the stability of sea turtle

populations, many beaches surrounding the park are supposedly undergoing a high

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

(Canadian Organization for Tropical Education and Rainforest Conservation) started a

five-year long feasibility study in 2004 with the aim of determining nesting populations

and poaching rates of C. mydasand D. coriaceaon North Beach (the beach just north of


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Laguna Tortuguero) and occasionally Hawksbill (Eretmochelys imbricata) and

Loggerhead Turtle (Caretta caretta).

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

well as collaborating on the data collection and analysis, GVI and COTERC shared datawith the CCC (Caribbean Conservation Corporation) in order to gain more knowledge

from tagged turtles and compare poaching rates of turtles nesting on protected National

Park beaches.

3.2. Aim

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

harvesting of turtle eggs, and to a lesser extent turtle meat, on the North Beach. Thus,

the aim of this project is to study the spatial and seasonal distribution of nesting females,

the number of mature females, illegal harvesting of turtle meat and eggs, and natural

predation of nests. Through these means the project aims to study, monitor and protect

the sea turtles coming to nest on the North Beach, as well as compare the data with

other important nesting sites like the TNP.

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 (5 kilometers)

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

southern point until Laguna Cuatro (103756,3N 833225,7W) in the north. Although

this beach is not within the TNP boundaries, it is situated within the Barra Colorado

Wildlife Refuge which, like the TNP, also is managed by ACTo (Area de ConservacinTortuguero) under MINAE the Costa Rican Ministry of Environment and Energy).

The study area begins at Mile 0 just north of Tortuguero river mouth (103551N

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

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


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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 Marand Turtle Beach Lodge) and a few ranchos and houses are built along the study beach.

On the southern side of Tortuguero river mouth is Tortuguero beach where 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 with a typical high energy-beach. The

width of the nesting beach platform (or berm) vary 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 plants such as 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

(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, coconuts husks and a largeamount of plastics, trash, beer bottles etc...

3.3.2. Daily track census and nest surveys

The turtles found in this area are D. coriacea, nesting from March to mid-July, C. Mydas,

nesting from June to November, and occasionally E. imbricataand C. caretta, nesting

from June to September (Trong et al., 2004). Because of this our surveys were

conducted every day and night from March to June and will continue through November

2006. In between GVI expedition phases COTERC alone conducts all surveys.

The daily track surveys began every day at 6:00 am and finished by 7:30 am and

consisted of walking the beach between mile 0 and 3 1/8, recording and monitoring the

tracks and nests from the night before. The day team identified tracks as full (turtle

nested), half moon (non-nesting emergences in which the track takes the form of a


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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 are then

identified as natural (if remained in its original state), predated by an animal or poached(with signs of stick marks, exposed egg chamber, eggs shells on the sand or human foot

prints).

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

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

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

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

number was recorded and checked against CCC tagging data.

3.3.3. Night surveys

Each night there is a survey consisting of walking the beach between mile 0 and 3 1/8

during 5 hours (21:00 to 02:00) and since 5 June the night surveys where divided in 2

shifts (20:30 to 00:30 and 00:00 to 04:00). 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 in length and only one night team goes out at the same time (except between

00:00 and 00:30 where 2 teams meet), there was a high possibility that not all turtles

were observed while nesting at night. When this happened their tracks were

documented by confirming that there were two sets of tracks (one ascending and one

descending the beach). In this case the methodology used was the same for the day

protocol.

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

time that the track was encountered and the species. The initials of each member of the

team, as well as mile marker number and GPS of each nest, were recorded every time.The position of the nesting turtle (turtle facing North, South, East or West) and the

vertical position of the nest in the beach (Open, Border or Vegetation) were recorded. If

the nesting process was observed, a count of the number of eggs (and for D. coriacea

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

also noted.


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3.3.4. Tagging

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

flipper using Monel #49 tags (National Band & Tag Co., Newport, USA). The 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 after having

completed the nesting process, while they were covering the nest or returning to the

ocean. Evidence of old tags in the flippers, old tag notches (OTN) or old tag holes

(OTH), was also recorded, as well as evidence of trauma or parasites due to old tags.

3.3.5. Biometric Data

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

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

includes fertile and infertile eggs.

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 reviewed three times to allow for

precision and the average of the three measurements was used as the final

measurement.

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

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 (CCWmax): Measured at the widest part of

the carapace from one side to the other.

Deformation or missing pieces of the carapace and flippers or any other relevant data

were also recorded.


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3.3.6. Turtle disease or injuries

Fibropapillomatumours, deformation or missing pieces of the carapace and flippers, as

well as any other relevant data was also recorded inspecting the turtle, after the

oviposition process, using a flashlight with a red light.

3.3.7. Nest Survivorship and Hatchling success

Samples of nests were marked using triangulation in order to locate the nest at

estimated hatchling time. During oviposition triangulation was conducted using three

pieces of flagging tape (tags) which were attached to vegetation behind the nest. The

distance from the centre of the egg chamber to each of these tags was measured, to thenearest cm, whilst the turtle was still laying eggs. The distance to the most recent high

tide line was also recorded. When it was time to excavate the nest, the triangulation

allows finding the location of the egg chamber at the site where the three tag lines

crossed. Three tags were used to compensate for the loss of any tapes. If one tag was

lost it was still possible to locate the nest using the other two tags.

3.3.8. Physical Data

The ambient temperature as well as rainfall and relative humidity were taken on the

beach at 6:00 a.m. and 6:00 p.m. on a daily basis. The ambient temperature and relative

humidity were recorded with a handheld Skymaster device and rainfall was recorded

from a rain gauge positioned at Cabinas Vista al Mar, on the upper platform of the

beach, with a PVC tube (8.5 cm 160 cm).

3.3.9. Human impact data

Due to the recent increase in human activity on the North Beach all artificial light (whiteor red) observed during the night surveys were recorded. As well as the number of

people, fires and tourist with or without guide.


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3.4. Results

Data was collected from 1st March to 15th June, covering 3 of the 4 months of the

Leatherback Turtle nesting season. The total number of morning and night surveys was

108 and 107, respectively.

During the daily track census a total of 668 6/8 miles (321 hours) was walked, taking an

average of 1 hour and 30 minutes to complete the 3 1/8 miles of the beach. Meanwhile,

the nightly surveys covered 878 miles (507.5 hours), taking an average of 4.78 hours to

walk an average of 9 miles per night.


Without taking into consideration the half moons, lifted or dead turtles, 59% (n=44) of theturtles that came onto the beach to nest were seen during the nights patrols. The

remaining 41% were from tracks found but no turtle seen, 14% (n=10) of which were

observed during nights patrols and 27% (n=20) during the daily track census. Only 4

turtles were observed doing a half moon.

The tracks encountered on the North Beach were identified as leatherback, green,

hawksbill and loggerhead turtles. A total of 103 tracks were observed, divided into 71

nests and 32 half moons. The nests were 73% Leatherback (n=52), 17% Green (n=12),

7% Hawksbill (n=5) and finally, 3% were Loggerheads (n=2). The horizontal distribution

of these nests on the beach was 76% in the open area (n=54), 17% in the border (n=12)

and 7% in the vegetation (n=5). See details in table 3-1.

Table 3-1. Number of nests, half moons and horizontal distribution of nests from the North Beachbetween March 1st and June 15th 2006.

The first sea turtle activity recorded was a Leatherback half moon the 2 nd March, but the

first nest was not until the 5th March. The first green turtle nest and half moon were

Horizontal distributionof the nestsSpecie Nest Half

moonOpen Border Vegetation

Leatherback 52 21 47 5 0

Green 12 10 4 4 4

Hawksbill 5 1 1 3 1Loggerhead 2 0 2 0 0

Total 71 32 54 12 5


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54%

4%

7%

35%

Natural

Erosion

Unknown

Poached

7/8 (1 nest, 1 half moon), mile 2 (1 nest, 1 half moon), mile 2 3/8 (0 nests, 1 half moon)

and mile 2 6/8 (1 nest, 0 half moons). See figure 3-2 A & B for the spatial distribution

(from Mile 0 to mile 3 1/8) of turtles nested on the North Beach. See Appendix B for a

more detailed figure.

3.4.2. Monitoring of nests

Out of the 71 nests on the North Beach until 15 th June, 54% seemed to be left in their

natural state without any signs of poaching, erosion or predation (Leatherback: n=29,

Green: n=7, Hawksbill: n=1 and Loggerhead: n=1). Based on various evidence such as

human foot prints, stick marks, egg shells and/or an exposed egg chamber, 35% of the

total nests were poached (Leatherback: n=16, Green: n=4, Hawksbill: n=4 and

Loggerhead: n=1). 4% of the nests were affected by the erosion (Leatherback: n= 3).

Finally, the remaining 7% were from those nests where it was not possible to determine

whether they were poached, eroded or left in their natural state. See the figure 3-3.

Figure 3-3. Destiny of the nests (all species) on the North Beach between March 1st and June 15th2006.


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0

2

4

6

8

10

12

14

16

20:00 20:30 21:30 22:30 23:30 00:30 01:30 02:30 03:30 04:00

Nesting turtles

3.4.3. Monitoring of female turtles

During the night surveys, 51 female sea turtles were observed during 8 of the 9 possible

nesting activity processes. 18% were emerging from the sea (n=9), 10% were selecting

the nest site (n=5), 8% were digging the body pit (n=4), 24% were digging the eggchamber (n=12), 12% were in the oviposition process (n=6), 16% were disguising the

nest (n=8) and finally, 4% were returning to the sea (n=2). Furthermore, out of the 8%

(n=4) of turtles which were observed attempting to nest, one Green was digging the egg

chamber at the water edge and three times leatherback turtles came up on the beach

but did not lay any eggs (observed selecting the nest site and twice the egg chamber

was dug as well). Other females found on the North Beach were a dead Hawksbill turtle

which appeared the morning of the 2nd April without any signs of poaching, and a lifted

Hawksbill on the 10

th

June.

The earliest turtle coming to nest at night was a Hawksbill found digging the egg

chamber at 20:47. Yet, the latest turtle nesting could not be determined, since the beach

was left at 02:00, between March 10to June 4, and at 04:00, between June 5 and June

15. However, during the morning census, new turtle tracks (nests and half moons) were

still being recorded. The hours that presented a higher nesting activity were between

23:00 and 01:30, where 67% (n=31) of the turtles were observed during the laying

process. See figure 3-4.

Figure 3-4. Temporal activity distribution of the 4 studied species (error bars 5%) on the North Beachbetween March 1st and June 15th 2006.


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0

2

4

6

8

10N

NE

E

SE

S

SW

W

NW

The orientation of the 27 females seen during the oviposition process was 4% heading

North (n=1), 4% Northeast (n=1), 7% East (n=2), 11% Southeast (n=3), 15% South

(n=4), 37% West (n=10) and finally 22% Northwest (n=6). See figure 3-5.

Figure 3-5. Nesting orientation of the 4 studied species (n = 27) on the North Beach between March1st and June 15th 2006.

3.4.4. Tagging

Of the total females seen during the night patrols, 15 (38%) were already tagged, 20

(51%) were newly tagged in 2 flippers (20% of them showing 1 or 2 evidences of old

tags OTH or OTN) and 4 (10%) were tagged in one of the flippers (100% of them witha minimum of 1 OTH). None of the newly applied tags were lost.

The tags applied by Cao Palma Sea Turtle Monitoring Programme are shown in table

3.2

Monel tags Iconel tagsVA8205-VA8208 CP0001-CP0006VA8210-VA8214 CP0008VA8217-VA8218 CP0010-CP0019

VA8222-VA8224 CP0022-CP0025VA8226 CP0035VA8228 CP0041VA8231-VA8232VA8249

Table 3-2. Tags applied by Cao Palma Sea Turtle Monitoring Programme from 1st March to 15th June

2006.


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The 15 turtles that arrived to nest at the North Beach and were already tagged, came

from other turtle monitoring programmes. 58% came from Tortuguero (tagged by the

CCC), 12% from Playa Chiriqui, 24% from Pacuare, and 6% came from Playa Soropta in

Panama, all of which are situated along the Caribbean Coast south of Tortuguero. The

re-nesting interval from 4 leatherback turtles observed on the North Beach during thestudied period was an average of 27.2 days.

3.4.5. Biometric data

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

the leatherback turtles coming to nest in the North Beach during the studied period 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 slightly higher (155.8 cm) that the mean

carapace length of newly tagged females with old tag holes or notches (152.5 cm), and

that of previously tagged females (148.5 cm). The mean carapace width of newly tagged

females with no evidence of previous tags was also slightly higher (118.8 cm), than the

other two categories (109.1 and 110.0 cm, respectively). The mean of fertile eggs was

slightly higher for newly tagged females (88 eggs) with no signs of previous tagging than

for the rest of females (67 and 75 eggs, respectively). On the other hand, the mean of

the infertile eggs was very similar between the newly tagged without any evidence of old

tags (25 eggs) and the previous tagged females (23 eggs), which were smaller than the

mean of the newly tagged with evidences of old tags notches and holes (32 eggs). See

table 31-3.

CCLmin (cm) CCWmax (cm) Fertile eggs Infertile eggsSample

N X .. N X .. n x .. n X ..

Newly tagged no OTH/OTN 6 155.8 5.2 6 111.8 5.0 5 88 5 5 25 11Newly tagged with OTH/OTN 3 152.5 0.4 3 109.1 1.2 1 67 / 1 32 /Previously tagged 17 148.5 6.5 16 110.0 5.9 10 75 16 10 23 8.3

Table 3-3. Leatherback mean carapace length, carapace width and clutch size on the North Beachbetween March 1st and June 15th 2006.

The mean carapace length, carapace width and clutch size of green turtles is shown in

table 3-4. As seen for Leatherbacks, the mean carapace length of newly tagged green

with no evidence of previous tags was slightly higher (104.0 cm) that the mean carapace

length of previous tagged females (90.8 cm). The mean carapace width of these newly


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tagged green females with no evidence of previous tags was also slightly higher (93.9

cm), than the other category (78 cm). The number of fertile eggs was higher for the

previous tagged turtles (132 eggs) than for the newly tagged (119 cm).

CCLmin (cm) CCWmax (cm) Clutch sizeSamplen x .. n X .. n x ..

Newly tagged Green no OTH/OTN 7 104.0 4.4 7 93.9 6.0 4 119 17.3Previous tagged Green 1 90.8 / 1 78.0 / 1 132 /

Table 3-4. Green mean carapace length, carapace width and clutch size on the North Beach betweenMarch 1st and June 15th 2006.during.

The mean carapace length of newly tagged Hawksbill with no evidence of previous signs

was a little smaller (89.3 cm) than the mean of previous tagged turtles (93.6 cm). Like for

the carapace length, the mean carapace width of newly tagged hawksbills with no

evidences was also smaller (75.5 cm) than for the previous tagged females (85.1 cm).

However, the clutch size was slightly higher in the newly tagged turtles (151 eggs) than

for the previously tagged (149 eggs). See table 3-5.

CCLmin (cm) CCWmax (cm) Clutch sizeSample

N x .. n X .. n x ..

Newly tagged Hawksbill no OTH/OTN 2 89.3 3.3 2 75.5 4.6 2 151 29.7Previous tagged Hawksbill 1 93.6 / 1 85.1 / 1 149 /

Table 3-5. Hawksbill mean carapace length, carapace width and clutch size on the North Beachbetween March 1st and June 15th 2006.

As shown in table 3-6, the mean carapace length of newly tagged loggerhead with no

evidence of previous signs was smaller (97.2 cm) than the mean of newly tagged

loggerhead with signs of previous tags (100.4 cm). The mean carapace width of newly

tagged females with no evidences was higher (91.7 cm) than for the other category (89.3

cm). No previously tagged loggerhead was seen during the studied period. Unfortunately

it was possible to count only one Loggerhead clutch, and the number the eggs counted

were 136. See table 3-6.


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CCLmin (cm) CCWmax (cm) Clutch sizeSample

N x .. n X .. n x ..

Newly tagged Loggerhead no OTH/OTN 1 97.2 / 1 91.7 / 1 136 /Newly tagged Loggerhead with OTH/OTN 1 100.4 / 1 89.3 / 0 N/A

Table 3-6. Loggerhead mean carapace length, carapace width and clutch size on the North Beachbetween March 1st and June 15th 2006.

The mean carapace length, carapace width and clutch size of the Leatherback found on

more than one occasion, is shown in the Table 3-7. Three times the same turtle was

found the CCWmax measurements had a higher level of precision than the CCLmin

measurements. On the contrary, the measurements from the three turtles that were

found on two occasions, the CCWmin had a lower precision than the CCLmin. See table

3-7.

CCLmin (cm) CCWmax (cm) Fertile eggs Infertile eggsEncounters

N X .. Range n x .. Range N x .. n x ..

3 1 145.0 1.2 0.0 - 3.0 1 107.8 0.3 0.0 - 0.6 3 0 0 3 0 02 3 150.6 4.3 0.0-1.1 3 109.9 3.5 0.0-5.7 3 76 10 3 30 11

Table 3-7. Mean and range carapace length and width and clutch size of leatherback turtles foundmore than once on the North Beach between March 1st and June 15th 2006.


A total of 46 sea turtles were examinated after the oviposition process to monitor theexternal aspect of the turtle (bites, deformations or missing parts of the body, parasites,

epibionts, etc.) and the possibility of disease like the fibropapilloma tumors. No

individuals were recorded to be affected by fibropapillomaand only one turtle was found

washed up by the sea, without any external mark or injuries. 70% (n=32) of the turtles

examined had a minimum of one bite on their body. See figure 3-8.


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Front rightflipper, 21%

Rear right flipper,20%

Rear left flipper,20%

Front left flipper,13%

Epibiontes, 15%

Carapace, 7%

Mutilations, 1%

Death, 1%

Figure 3-6. Distribution of the injuries presents on the turtles checked on the North Beach betweenMarch 1st and June 15th 2006.

3.4.7. Nest survivorship and hatchling success

From the seemingly 15 natural nests out of 71 total nests on the North Beach, only 5

hatched. For the other 10 nests, any evidence of emergence success was recorded. The

5 nests that hatched took an average of 63.4 days between the incubation period and

the emergence of the hatchlings on the surface of the beach.

The first nest marked by triangulation was on the 10th

May, since then 14 more nestshave been marked using the triangulation method. None of these nests will be

excavated until 12th July. For this reason the hatchling success is not analyzed in this

report.

3.4.8. Human impact data

During the night surveys the presence of 2 strong torches (from the guards of Turtle

Beach Lodge and Cabinas Vista al Mar) were recorded on almost all nights. White lights

were observed 50% of the time throughout the night patrol, as well as fishermen,

bonfires, tourists and local people walking the beach at night. In various places along the

beach, a few permanent lights have been observed, including a very bright external light

on the top part of the beach in front of Turtle Beach Lodge. This was changed for a red

light at the beginning of May. Moreover, a fishing line just before mile 1, of approximately

50 meters length, was recorded on all nights.


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3.5. Discussion


Although Leatherback nesting was observed from 2nd March to 15th June, the nesting

season 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. At the time of

writing Leatherbacks are still coming up to nest on the North Beach as well as other

species (Greens, Hawksbills, and Loggerheads).

The total number of nests recorded on the North Beach during this study was 71. More

than half of the turtles were seen during the night patrols, thanks to the large number of

hours and miles walked on the beach. The majority of these nests were from leatherback

turtles, however a considerable number of nests from other species were also recorded

between March and mid-June. Especially those of green and hawksbill turtles, which

started to arrive, on 23rd and 26th April, respectively, more than one month previous to

their respective nesting season beginning in June.

The seasonal distribution of leatherback turtles was higher between 13 th and 30th of April

and between 17th May and 14th June. If we add the four species together, the higher

densities were between 13 April and 5 May, 17 May and between 24 May and 13 June.See Appendix A.

The higher density of nests per mile was found at the first stretch of the beach, between

mile 0 and 1, with a 42% of total nests. The sectors between mile 1 and 2 and between 2

and 3, had both 30% of the nest. In particular, the actual zones with the higher density

were at mile 3/8, mile 5/8 and at mile 2 7/8. See Appendix B.

3.5.2. Monitoring of nests

Illegal take of turtle nests was recorded throughout the entire study period. A minimum of

31% of the Leatherback nests were poached, as well as 33% of Green, 50% of

Loggerhead and finally 80% of the Hawksbill nests. The very low levels of nesting

Hawksbills observed in the Tortuguero area are disconcerting. To ensure increased

Hawksbill nesting in the future, any action aimed at protecting nesting females, nests or


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females in the internesting habitat should be encouraged (Da Haro & Trong, 2005).

Hawksbill nesting at Tortuguero are now at such low levels that every female and nest

are important (Trong et al. 2005).

Although we estimated the minimum poaching rate for each species, this does not reflectthe actual poaching that occurs on the beach. One of the causes of this under-estimation

is due to the act of erasing tracks and nests once recorded on the beach. This act has

three big consequences:

1. The night patrol has to stay with the turtle throughout the nesting process

(sometimes more than two an a half hours) in order to be able to erase the tracks

afterwards. In this way, other turtles that are nesting at the same time in other parts

of the beach are lost, i.e. not recorded (a nest was found during the night but not the

turtle in 14 % of the total time spent on the beach. See 3.3.2).

2. There is a risk of damaging the nest when erasing tracks and attempting to

camouflage the bodypit, such as excessive compact sand on top of the nest.

3. Erasing the tracks could be encouraging illegal harvest of the eggs and poachers

could also erase new tracks without leaving any evidence of the harvested nest and

thus causing inaccuracies in the data collection.

For those reasons, the erasing of tracks was stopped in May. The final report of the

Leatherback Nesting Season 2006 will be able to give an indication of whether the illegal

harvesting of the nest is statistically different with or without erasing the tracks. In order

to protect the hawksbill nests as much as possible, an exception to the above was

agreed to apply in that the tracks will be erased after all Hawksbill encounters, with the

purpose to minimize the possibility for the poachers to find the nest.

In comparison to the previous years, the poaching rate on the North Beach is decreasing

(COTERC Report 2006, unpublished), and as shown in others Sea Turtle Monitoring

Programmes, the constant presence of the researchers on the beach may be one of themajor reasons for the reduction of illegal harvests.


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3.5.3. Monitoring of female turtles

91% of the times the turtles came out to nest between 21:30 and 01:30 and 52% of

those were between 23:30 and 00:30. 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 higherdensity hours, will be continue until a change of this density.

The study of the orientation of the turtles when nesting will continue. At the moment it

seems that the favourite orientation of the turtles while there are nesting is west,

followed by northwest and south.

3.5.4. Tagging

During the 507.5 hours of night patrol and a total of 39 worked turtles, 4 did not have anytags and presented one or two OTH or OTN, and other 4 other had only one tag and

also presented one or two OTH or OTN. This information will be very useful in terms of

estimating tag loss and annual survival probabilities (Da Haro & Trong, 2005).

On the other hand, it is known that other projects along the Caribbean Cost of Costa

Rica, with a bigger population of leatherback turtles (with the exception of the CCC) are

also tagging using PIT tags (Passive Integrated Transponder) placed under the skin.

These PIT tags are read using a scanner device. Since leatherback turtles can travel

relatively long distances during the same nesting season (L. Chaparro, pers comm.), it is

possible that a number of turtles, in particular those presenting old tag notches or holes,

possess a PIT in their bodies which we can not detect on the North Beach because of

the absence of the required equipment. Future investigation, in particular for the

Leatherback turtles, could prove the need of this kind of expensive equipment.

3.5.5. Biometric data

Mean carapace measurements of previously tagged leatherback and green turtles weresmaller than those of newly tagged with evidences of old tag or notches and smaller

than the newly tagged without evidences. On the contrary, the mean carapace

measurements of previously tagged hawksbill were greater than those of newly tagged

without evidences of old tag or notches. With the loggerhead turtles, the mean carapace

length of the newly tagged with evidences was higher than the one without evidences


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but the mean carapace width was the reverse. In theory (L. Chaparro, pers. comm.), the

newly tagged turtles (assumed younger) are in general smaller than the previously

tagged turtles (assumed older), but so far this theory could only be applied to the

hawksbill measurements.

One of the reasons for these results could be that this is the first year that a tagging

programme is taking place on this beach. Consequently, we are not able to identify the

re-migrating turtles (turtles that came to nest in previous years) from the neophytes ones

(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 programmes 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 reality.

Despite this fact, thanks to encountering re-nesting turtles, the precision could be

calculated and the higher range obtained was between 0.0 to 3.0 centimeters for the

length and 0.0 to 5.7cm for the width, showing that the precision obtained with the length

measurement was higher than the width. Consequently, training of correct and precise

measuring techniques of the length and width of the carapace of the four different

species is of extreme importance and urgency. During next phase such training will be

provided in order to make sure that measurements are recorded as precise and accurate

as possible.


Out of the 46 individuals examined, not one was recorded to be affected by

fibropapilloma tumors. However, the majority of these females (n=32), presented a

minimum of 2 bites somewhere on the body, the majority of bites located on the right

front flipper and on both rear flippers.

3.5.7. Nest suvivorship and hatchling success

Until the end of this study, only 33% of the nests that should already have hatched did in

fact hatch. Because the triangulation of nests did not start until the 10 th of May, the

reasons for this low rate of emergence success can not be estimated. However, this low

emergence success could be due to an actual higher rate of poaching than the recorded.


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In addition, a large number of nests were next to the high tide potentially causing

inundation or erosion of various nests, and the low success could also be due to

depredation inside the nest, infertile eggs or females and a variety of other factors not

mentioned here.

Excavations of the nests will start next phase, on 12 th July. These excavations should

give provide further information about the final destiny of the eggs on the North Beach.

The results will be presented in the final Leatherback Nesting Season 2006 Report.

3.5.8. Human Impact Data

Turtle Beach Lodge have shown a noticeable conservation effort as, in the middle of the

Leatherback Season, they changed the very bright external light placed on the top of the

beach for a less powerful red light. COTERC and GVI have been able to establish a

good relationship with the growing village of San Franciso and the increasing human

settlers on the parallel trail of the beach through various presentations, invitations to join

us on the beach, environmental education and English lessons, and it is hoped that this

will aid in reducing the poaching rate on the beach.


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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 also the largest nestingcolony for the endangered Green Turtle (Chelonia mydas). Because of 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, a long-term monitoring

station 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.

Avifauna monitoring programs in the past have combined the use of area searches,

constant-effort mist netting, and migration counts. 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 4 different habitats using area searches, point counts and various other

techniques.

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 will follow the protocol created by Steven

Furino.

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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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 canbe 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

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 C.

4.3.1. Point Counts

A point countsurvey records all study species3 seen or heard in a ten minute period at a

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

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

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

populations.

3 Study Species are subdivided into habitat types see appendix A


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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

A more structured method of recording breeding behavior has been introduced this

phase. Examples of behaviors which are recorded include: courtship displays; nest

building; copulation; and feeding young (see appendix B for further details). For this

protocol, only behaviors that are strongly correlated with probable or confirmed breeding

are recorded.

4.3.2. Area Searches

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

See appendix C 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 surveyors record only the selected study species for that habitat.

As with the point counts only positively identified species are recorded. Any rare birds

seen during surveys were recorded as incidentals. For each positive record made the

following data should be collected:


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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

subadults/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 ofday when birds might be observed. This includes relaxing in the rancho, eating dinner,

and birding whilst not on survey. Only species that have been classed as rare, vagrant,

hypothetical or unknown in the Checklist to the Birds of Tortuguerowere recorded.

In order to maintain a high standard of competency in the field both staff and Expedition

Members were given bird identification training and tests on a regular basis. The training

involved both in the field bird identification and laboratory training using Powerpoint

presentations. The presentation consisted of a mix of photographs, drawing and audio

bird calls to provide the EMs with a wide selection of examples of the key spices.


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4.4. Results

4.4.1. Survey Data

0

2

4

6

8

10

12

AM PM AM PM AM PM AM PM

CA CT NB CP

Figure 4-1 Distrubution of survey periods and study sites during Phase 4.

During Phase 4 a total of 56 RBP surveys were undertaken. Of these 17 were

undertaken on the Cleared Areas study site (10 dawn and 7 dusk), 13 on Cerro

Tortuguero (5 dawn and 8 dusk), 12 on the North Beach study site (7 dawn and 5 dusk)

and 14 on Cao Palma (9 dawn and 5 dusk).


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0

10

20

30

40

50

60

70

80

90

Passerini'sT

anager

White-c

rownedP

arrot

White-ring

edFlycatcher

Pale-billed

Woodpecker

Squirrel

Cuckoo

Boat-billed

Flycatcher

Thick

-billedS

eed-Finch

EasternKin

gbird

Palm

Tanager

Gray-capped

Flycatcher

Red-lore

dparrot

TropicalKingbird

Olive

-backed

Euphonia

Mealy

Parrot

SocialFlyc

atcher

Black-cheekedW

oodpecker

Blue-g

rayTanager

Black-mandibleTo

ucan

LesserGreenlet

Collared

Arac

ari

Keel-billed

Toucan

Clay-color

edRobin

Monte

zuma

Orop

endola

Blue-blackG

rassquit

GreatKisk

adee

Variable

Seedeater

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

A total of 26 species were recorded within the Cleared Areas study site. The top four

species were Montezuma Oropendola (Gymnostinops Montezuma), Blue-black

Grassquit (Volatinia jacarina), Great Kiskadee (Pitangus sulphuratus) and Variable

Seedeater (Sporophila corvine) accounting for 49% of all records within the study site.


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0

2

4

6

8

10

12

14

16

Amazon

King

fisher

GreatBlue

Heron

GreenB

ackedH

eron

SnowyE

gret

Sungrebe

GreatTina

mou

Little

Tinamou

RufescentTig

er-He

ron

Yellow-cro

wned

Night-H

eron

AmericanP

ygmy

King

fisher

Cattle

Egret

Bare-thr

oated

Tiger-heron

GreatC

urassow

GreenKing

fisher

Ringed

King

fisher

Anhin

ga

Green-B

ackedH

eron

GreenIbis

Figure 4-3 Key species recorded during surveys of the Cao Palma study site.

A total of 18 species were recorded within the Cao Palma study site. The top four

species were Green Ibis (Mesembrinibis cayennensis), Green-Backed Heron (Butorides

virescens), Anhinga (Anhinga anhinga) and Ringed Kingfisher (Ceryle torquatus)

accounting for 54% of all records within the study site.


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0

2

4

6

8

10

12

14

16

18

20

Barred-W

oodcreepe

r

Black-cheekedW

oodpecker

Black-Throated

Trogon

Pale-billed

Woodpecke

r

Plain-bro

wnWoodcreepe

r

Bright-ru

mped

Attila

Collared

Aracar

i

Short

-billedPigeon

Chestnu

t-backedA

ntbird

WesternSlaty-

Antshrike

LesserGreenle

t

Slaty-tailed

Trogon

Black-mandibleTo

ucan

Keel-billed

Toucan

Figure 4-4 Key species recorded during surveys of the Cerro Tortuguero study site.

A total of 14 species were recorded within the Cerro Tortuguero study site. The top four

species were Keel-billed Toucan (Ramphastos sulfuratus), Black-mandible Toucan

(Ramphastos swainsonii), Slaty-tailed Trogon (Trogon Massena) and Lesser Greenlet

(Hylophilus decurtatus) accounting for 64% of all records within the study site.


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0

5

10

15

20

25

30

35

40

BrownB

ooby

NeotropicCormora

nt

Wilso

n'sPlover

Collared

Plov

er

Sanderling

RoyalT

ern

Semipalmate

dPlov

er

Whimbre

l

Black-bellie

dPlov

er

Magnific

entF

rigatebir

d

Spotted

Sandpiper

BrownP

elican

Figure 4-5 Key species recorded during surveys of the North Beach study site.

A total of 12 species were recorded within the North Beach study site. The top four

species were Brown Pelican (Pelecanus occidentalis), Spotted Sandpiper (Actitis

macularia), Magnificent Frigatebird (Fregata magnificens) and Black-bellied Plover

(Pluvialis squatarola) accounting for 71% of all records within the study site.

4.4.2. Incidental Observations

14/04/2006 AMTortugueroNational ParkBeach

2 x Black-necked Stilt

18/04/2006 AM North Beach Mangrove Cuckoo10/05/2006 AM Cano Palma Roseatte Spoonbill

Table 4-1 Incidental recordings of rare species observed during phase 4.

Three rare species were observed outside of surveys. All of the species seen were

observed by more than one person and a detailed description of the species was taken

to confirm identification. In the case of all these species miss-identification would be

unlikely.


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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 fourth phase, this early set of data

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

The data obtained in this phase was collected using different methodology to that used

during the previous phases. The methodology had a limited list of target species

therefore no information on which of the study sites contains the highest or lowest

species diversity could be ascertained. This information has however been established

in the previous phases and was therefore deemed not necessary to confirm in this

phase.

The technique of using both area searches and point counts to conduct monitoring

surveys works as an effective indicator to determine the local bird presence. The two

survey techniques were combined in this phase to coincide with methodology

established by Steven Furino and allow a greater number of surveys to be undertaken.

During Phase 4 a total of 56 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 (see figure4.1).

Comparison between study sites is no longer examined as variation in the newly

adopted key species lists as they do not lend themselves to this form of comparison.

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. To aid with the WINGS database created by Steven Furino, the programme

will finally be installed on the Cao Palma computer and from Phase 5 it will be used

directly by the expedition in order to add all future data.

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

local bird populations. There has been a clear decline in certain species such as the

shore birds and some waders during this phase compared to last phase, specific

examples include Semipalmated Plover (Charadrius semipalmatus) and Little Blue


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Heron (Egretta caerulea). The decline in the presence of the species can be attributed to

normal migrating behaviour as these species breed in North America and only some non

breeding individuals will remain in Costa Rica.

Breeding evidence of a variety of species was recorded during the Phase 4 surveys.Species confirmed as breeding include, Great Kiskadee (Pitangus sulphuratus),

Montezuma Oropendola (Psarocolius montezuma), Rufous-ailed Hummingbird (Amazilia

tzacatl), Yellow-crowned Night-Heron (Nyctanassa violacea), Long-billed Hermit

(Phaethornis longirostris), Bare-throated Tiger-Heron (Tigrisoma mexicanum), Green-

backed Heron (Butorides virescens), Black-cheeked woodpecker (Melanerpes

pucherani) and Clay-colored Robin (Turdus grayi). Some of these records were obtained

off survey or during preliminary nest searches. In addition to these confirmed records

there was also a highly probable record of nesting Green Ibis (Mesembrinibiscayennensis). The lack of data on the breeding and nesting behaviour on this species

makes this finding very important and further work next phase will help to gain data on

this species.

The level of bird watching in personal time and the amount of previous birding

experience this phase was noted to be much lower than that of last phase. It is

reasonable to assume that these factors resulted in a much lower number of incidentals

being recorded. In respect to rare species recorded of survey only three species were

recorded which were Mangrove Cuckoo (Coccyzus minorm), Black-necked Stilt

(Himantopus mexicanus) and Roseate Spoonbill (Platalea ajaja).

The EBCP Resident Bird Project surveys undertaken during Phase 4 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.


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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

Phase 4 Science Report Final

Documents

Transcript of Phase 4 Science Report Final