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A Study of Tobago’s Nesting Beaches: Leatherback and Hawksbill

Turtles

Zoology Honours Project Amy Robb

0700072

Supervisors: Professor Roger Downie and Doctor Suzanne Livingstone Faculty of Biomedical and Life Sciences

University of Glasgow

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Abstract There are a number of threatened sea turtle species that nest and forage around the

island of Tobago including the leatherback (Dermochelys coriacea), the hawksbill

(Eretmochelys imbricata) and the green turtle (Chelonia mydas). This study surveyed

Tobago’s beaches in 2010 relevant to sea turtle nesting numbers, species and

topographical profile. Three index beaches were patrolled nightly between 1st March

and 30th September and eleven non-index beaches were patrolled weekly between 16th

June and 5th August in conjunction with the local NGO Save Our Sea Turtles (SOS)

Tobago. No green turtles were recorded nesting on Tobago in 2010 but they have been

reported to nest on the island in the past. Leatherback turtles were recorded nesting in

high numbers over the 14 beaches with a total of 448 confirmed nests and hawksbill

turtles were recorded nesting in lower numbers with 42 confirmed nests. Average false

crawl rates were calculated for leatherback turtles to be 16.7% over the three index

beaches on Tobago. Average false crawl rates were calculated to be higher for hawksbill

turtles at 25% over the three index beaches. All the beaches patrolled were profiled and

the profile was analysed in relation to nesting density and Google Earth and Bing Maps

were used to present the distribution of sea turtle nesting visually. The information

obtained provides a useful foundation from which further research can be developed,

including making a population estimate for the island.

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Table of Contents

Abstract......................................................................................2

Introduction Sea Turtles.......................................................................5 Tobago.............................................................................7

Sea Turtles In Tobago......................................................8 SOS Tobago......................................................................9 Assessing Population Size...............................................10 Beach Profiling................................................................11 Using GIS.........................................................................13 Project Aims....................................................................13

Methods Location of Study Sites....................................................14 Data Collection on Nesting Turtles.................................15 Beach Profiling................................................................17 Mapping..........................................................................18

Statistical Methods.........................................................19

Results Leatherback turtles..........................................................20 Nesting.................................................................20 False crawls..........................................................21 Beach Profiling.....................................................23

Hawksbill turtles..............................................................24 Nesting.................................................................24 False Crawls..........................................................25 Beach Profiling.....................................................27

Mapping...........................................................................28 Limitations in Data Collection..........................................45

Discussion Leatherback turtles..........................................................48 Nesting Behaviour................................................48 False crawls..........................................................49 Population Model.................................................51 Beach Profiling......................................................52

Hawksbill turtles...............................................................53 Nesting Behaviour................................................53 False crawls..........................................................55 Beach Profiling.....................................................57

Mapping...........................................................................58 Limitations and Recommendations.................................59

Recommendations and Future Research.........................60

Summary of Findings.................................................................62

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Afterword...................................................................................63 Acknowledgements...................................................................64

References..................................................................................65

Appendix.....................................................................................70

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Introduction

Sea Turtles

Sea turtles, along with tortoises and freshwater turtles belong to the order Testudines.

There are seven living species of sea turtles, six of which belong to the family

Cheloniidae: the hawksbill turtle (Eretmochelys imbricata), the green turtle (Chelonia

mydas), the flatback turtle (Natator depressus), the loggerhead turtle (Caretta caretta),

the olive ridley (Lepidochelys olivacea) and the kemp’s ridley (Lepidochelys kempii). The

leatherback (Dermochelys coriacea) (Davenport, 1997) belongs to the family

Dermochelyidae in which there is only one species. There is some controversy over the

East Pacific green turtle sometimes known as the black turtle. However, it is generally

accepted as a subspecies of the green turtle (Chelonia mydas agassizii), although some

researchers believe that it is a separate species (Chelonia agassizii) (Karl and Bowen,

1999).

Tobago has three of the seven species of sea turtles nesting on its shores, the

leatherback, the hawksbill and, although it has not been recorded nesting on Tobago for

several years, the green turtle (G. Lalsingh, personal communication, 2010).

The leatherback turtle is the largest of all the sea turtles, weighing over 900kg and with

a carapace of up to 188cm long (Scott, 2004). The carapace of the leatherback is unusual

in that it is formed from a layer of tough leathery skin instead of hard shell.

Leatherbacks are pelagic and the most widely distributed of the sea turtles, found in all

the oceans but the Arctic and Antarctic. They are highly adapted for a pelagic lifestyle,

with a unique flipper structure and flipper proportions to allow for powerful swimming.

Their large body size, effective insulation and control of their blood flow allows for great

diving depth and toleration of colder waters. In Tobago, the leatherback nesting season

is from March to August, but the season differs between localities. They nest

approximately every three years on average, emerging onto beaches in darkness to nest

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approximately every ten days and laying in total around four to eight clutches a season

(Reina et al, 2002). When they nest they use their back flippers to dig a hole around

80cm deep, and into it deposit 80-120 soft-shelled eggs, including infertile capsules, that

will take between 57 and 75 days to hatch, depending on incubation temperature

(Davenport, 1997).

The hawksbill is one of the smaller of the sea turtles, usually less than one metre in

length and around 80kg in weight. It is characterised by a hooked beak on its upper jaw

that is hawk-like in appearance (Spotila, 2004). This beak allows them to feed in coral

reefs on sponges. Their presence often indicates a healthy reef and it has even been

suggested that they have a positive effect on coral reefs, improving biodiversity and

maintaining community dynamics (Leon and Bjorndal, 2002). They are found in tropical

and sub-tropical seas around the world. The hawksbill is poached in large numbers, for

its meat and eggs, but mainly for its intricate shell which is used in tortoiseshell

products. Due to this, hawksbill populations have been under severe decline (Bjorndal,

Bolton and Lagueux, 1993; IUCN, 2008). Hawksbills will nest every two to three years,

coming onto the beach every 14 to 16 days and laying in total five to six clutches per

season. They dig a nest with their back flippers, around 40cm deep and deposit into it

around 160 soft shelled eggs, including infertile capsules (Burton and Burton, 2002).

They prefer to nest on isolated, small beaches in the vegetation zone and the hawksbills

small size and agility allows them to do so. The nesting season on Tobago is April to

September.

The green sea turtle is so named due to the green tinge to the fat found under the

plastron, caused by the diet they have. They are the only species of sea turtle to be

completely herbivorous, feeding on sea-grass meadows and algae in shallow, coastal

waters. They measure from around 81cm in length up to 120cm and weigh around

180kg. The green turtle is found in tropical and sub-tropical seas around the world

(Balazs, 1980).

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All three species of sea turtle nesting on Tobago are enlisted as Endangered or Critically

Endangered on the IUCN Red List of Threatened Species (IUCN, 2010).

Tobago

Tobago is the smaller of the two

islands making up the Republic

of Trinidad and Tobago, located in

the West Indies, as seen in Figure 1.

Tobago has a latitude of 11˚ 9` N,

and longitude 60˚ 40` W, and is

found to the North East of Trinidad.

It has a land area of 300km² and is

42km in length and around 12km

wide. Tobago is a volcanically

originated, rather mountainous island with a lot of the land covered by forest. The main

ridge dominates the island, being 29km long and reaching around 576m in height (Food

and Agriculture Organization of the United Nations, 1998). In the South West of the

island there is an area of flat land known as the coastal plain.

The coasts of Tobago consist of cliffs, rocky shores and sandy beaches. Much of

Tobago’s coastline is under threat of development, where, despite being home to a

large percentage of the islands marine and terrestrial biodiversity, there is only currently

one legislated marine park at Buccoo Reef (Tompkins, Adger and Brown, 2002). The

islands of Trinidad and Tobago are highly influenced by the rivers flowing into the

Atlantic Ocean such as the Amazon and the Orinoco which are controlled by the South

Equatorial Current. This current flows past Trinidad and Tobago therefore affecting the

salinity of the water at Crown Point, to the South West of the island. It also affects the

coastlines of the island. The Atlantic coastline experiences stronger currents and so the

Figure 1: A map of Trinidad and Tobago. Retrieved from the worldwide web 2010 from

www.grangecottagetobago.com/tobago.html

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waters are less calm than on the Caribbean coastline. Tobago experiences a semi-diurnal

tide, the cycle lasting just over 12 hours (Kenny, 2000).

Sea Turtles in Tobago

There are very few data on the distribution of sea turtles in Tobago. Dow et al (2007)

reported that hawksbills are found nesting mainly along the Caribbean side of Tobago,

in particular to the north-east. Leatherbacks have been recorded nesting all around the

island on both the Caribbean and Atlantic sides, however most occurrences of nesting

are on the Caribbean coastline. The green turtle has been recorded nesting in small

numbers on the Caribbean side of Tobago (Dow et al, 2007), however there have been

no recorded incidences of greens nesting on the island in the last few years. The last

recording of the tracks of a green turtle on Tobago was in 2007, the outcome of the

nesting attempt was unknown (G. Lalsingh, personal communication, 2010). Sightings of

greens in the water, however, are common, with the turtles feeding on the sea-grass

beds and algae surrounding the island (Kenny, 2008).

An honours project in 2005 looked at the conservation and distribution of nesting sea

turtles around the island of Tobago (Cawley, 2005). The study found that turtles nested

mainly on the Caribbean side of the island rather than the Atlantic coastline. The nesting

population of female leatherbacks was estimated to be between 155 and 258. The

nesting population of female hawksbills was estimated to be between 50 and 88. There

were no recordings of green sea turtles but were reports of green turtles foraging in

Tobago’s coastal waters. Through interviewing local people they found that there has

been a noticeable decline in nesting turtle numbers in recent years and that there was a

lack in knowledge and awareness of the conservation status of sea turtles and their

vulnerability (Cawley, 2005).

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Since 2005 there have been several other research projects on the sea turtles of Tobago

including:

-A Masters of Research project in 2008 collected incubation temperature profiles from

leatherback turtle nests on Tobago. The study found that a lower mean incubation

temperature led to advantageous morphology traits in hatchlings (Mickelson, 2008).

-A Masters of Research Thesis in 2010 looked at how the morphology and artificial light

influenced the terrestrial transit in leatherbacks nesting on Tobago. It was found that

morphology and light had little influence on the transit in leatherbacks however artificial

light did cause confusion and disorientation (Walker, 2010).

All of the research carried out on the sea turtles of Tobago helps to collect information

on a threatened species where data is much needed. The main threats to the sea turtles

in Tobago are poaching for meat, eggs and shells. Turtle meat and eggs are a traditional

cuisine in Tobago and the shells are used to make jewellery and decorative crafts.

Coastal development is also becoming an increasing threat. Beach chairs, gazebos and

litter obstruct and can be danger to nesting turtles and light pollution confuses both

adults and hatchlings. Fishing is also a common practise in Tobago and turtles can

become entangled in nets and lines (www.seeturtles.org).

All sea turtles that inhabit or nest on the islands of Trinidad or Tobago are protected by

the Conservation of Wildlife Act (1963) and the Fisheries Act (1975), however illegal

poaching still occurs often. All sea turtles and their eggs are only officially protected

during the nesting season and can be hunted legally from October to February, despite

their high conservation status (Lalsingh, 2010).

SOS Tobago

Data collection on sea turtles in Tobago first began in 2000 when a non-governmental

and non-profit organisation, Save Our Sea Turtles (SOS) Tobago was established. SOS

Tobago is community-based and involves both local and foreign volunteers doing much

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of the data collection. SOS Tobago is involved in four main activities: research,

protection, education and eco-tourism (Leotaud, 2001). They protect the sea turtles by

consistently monitoring three main index beaches through night patrols during the

nesting season. During these patrols data is collected and this activity also helps to

prevent poaching. SOS volunteers tag (using both Passive Integrated Transponder tags

and flipper tags) hawksbills and leatherbacks that come up to nest, and recording other

relevant data about the nesting turtles. SOS Tobago also provides assistance for any

graduates or undergraduates that wish to carry out research projects in Tobago. They

believe strongly in education to help conserve the sea turtles and raise public awareness

through talks, school visits and field trips. They also help to educate tourists, fisherman,

tour guides and villagers. They are involved in eco-tourism by working with tour guides,

guest houses and hotels to encourage turtle friendly practices on the nesting beaches.

Assessing population size

Many other small islands like Tobago have nesting turtle populations. Barbados, for

example, is an island slightly bigger than Tobago 300km away, with nesting populations

of sea turtles. Like Tobago, Barbados has leatherbacks, hawksbills and greens in the

area. Loggerheads are also seen but rarely (Horrocks, 1992). The Barbados Sea Turtle

Project was initiated in 1987 and has carried out a large amount of research there

(Beggs, Horrock and Krueger, 2007). Initially they monitored populations to allow

population estimates of nesting sea turtles populations on Barbados. However now,

beach nesting monitoring occurs, as does in water monitoring. They also do genetic

analysis, rescue and rehabilitation, and satellite telemetry (Barbados Sea Turtle Project

Website).

To be able to conserve sea turtles, knowledge on population size and distribution is key

(Hays, 2000). However, this can be a problem, when the species remain submerged

except for air replenishment, for most of their life-span, as is the case with sea turtles.

Indeed, it is only females that emerge to nest on a beach and they only do so once every

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two or three years. Long term patrolling of beaches during the nesting season, and the

use of tagging as an aid, is one way to estimate the turtle population of an area. By

regular patrols, threats to the turtles and their eggs through poaching are reduced and

an estimate of turtle nesting numbers can be produced (Horrocks, 1992). Counting

tracks and nesting females is relatively simple, but the resulting data can be difficult to

interpret. Females will only nest once every two or three years and may come onto the

beach several times in one season. Also the females may not use the same beach every

season. Nesting female numbers can show considerable variation from year to year as a

consequence of this. This problem can be reduced by using population models which

can estimate turtle populations for a specific area for a season whilst taking into account

these factors. A recent study by Allen et al (2010) used this method, applying a Poisson

distribution to the number of seen turtles to estimate the number of unseen turtles on

Cousin Island of the Seychelles. There are now several models that have been developed

that can be used for this purpose.

Beach Profiling

Horrocks (1992) states that in conserving marine turtles it is first important to ascertain

what areas and conditions are critical to their survival. Beach surveys can monitor

nesting turtles, allowing numbers and trends to be determined. Beach profiling,

however, can also be used to monitor the nesting habitat of turtles. There have been

long-term concerns over the changing conditions of coastal sandy beaches and their

ability to support nesting turtle populations (Fish et al, 2008). There has been an

increase in human activity in coastal areas with more coastal development, tourism, and

industrialization. The Wider Caribbean Region is classed as a Small Island Developing

State, or SID, and many are tourist-dependant, including Tobago. This means that the

coasts are more likely to be developed and so the beaches are more likely to be affected

by light and noise pollution, and erosion (Varela-Acevedo et al, 2009). There is a lack of

knowledge on what the important features are of a nesting beach for different species

of sea turtle and what is important in nest site selection. Through beach profiling it may

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be possible to look at the profile of a beach and determine if it is suitable for nesting

turtles.

When a female decides to nest several factors can influence the choice of beach.

Leatherbacks prefer a deep water approach and little or no reef and they require a wide

entry onto the beach (Pritchard, 1971). They also prefer a high energy beaches where

currents produce a steep-fronted profile (Bouchard and Bjorndal, 2000). This could be

due to the difficulty leatherbacks have on land locomotion. A steep approach would

allow the nest to be above high tide levels without the turtle having to travel long

distances up the beach (Hendrickson, 1980). They also prefer open sandy beaches to

protect their plastron from damage on sharp reefs (Eckert, 1987). Green turtles are

thought to prefer beaches with a slightly steep sloped entry and moderate to high

energy waves on approach (Brock, Reece and Ehrhart, 2009). Hawksbills, however,

prefer a steeper slope and calmer waters on emergence on isolated, sheltered beaches

(Varela-Acevedo et al, 2009). They are one of the more flighty species of sea turtles

when nesting and it takes very little movement or noise to cause them to abandon a

nesting attempt. The nesting beaches of hawksbills usually have offshore barrier reefs,

and thick vegetation. Hawksbills are known to nest high on the beach, often amongst

vegetation (Witzell, 1983).

Once a turtle has started to lay its eggs is not easily disturbed, but when a female is

emerging from the sea or attempting to nest she may be startled by lights, noise or

unusual activity and return to sea without nesting. A nest site may be abandoned if an

obstruction is met such as the roots of trees or rocks, if the physical properties of the

sand are not correct or if the egg chamber collapses repeatedly. This is known as a false

crawl or a non-nesting emergence. Turtles may false crawl several times before

choosing a suitable nesting site. The rates of these false crawls may help to determine if

the suitability of the beach is changing over time (Williams-Walls et al, 1983).

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Using GIS

Geographic Information System or GIS is becoming increasingly popular. It is a

programme that can store, analyse, and present data linked to a location (Schuurman,

2004). The use of GIS in turtle conservation could help to improve our understanding of

exactly where turtles are nesting in an area and what beaches are critical to turtle

nesting and conservation. The areas in which GIS can be used in turtle conservation are

numerous. Data collected over many years can be transformed into a simple format that

is visually easy to understand and from which conservation management plans can be

formed (Breman, 2002). A study by Maktav et al (2000) formed a digital terrain model of

the Lztuzu beach in Turkey where sea turtles nest. They found that GIS was extremely

useful in presenting the data. They state that GIS can be used to combine data on land

and water and that the data can be visually examined to determine how turtles are

affected by environmental, land use and ecological changes.

Project Aims

This project is designed to collect information and draw conclusions on the beaches of

Tobago, relevant to nesting sea turtle numbers, sea turtle species and topographical

profiles of the beaches.

The aims of this project were to:

Estimate the populations of the different species of sea turtles nesting in

Tobago, looking at previously un-monitored beaches using a model, and data

from three index beaches

Profile the major sea turtle nesting beaches on Tobago and look at these in

conjunction with nesting density

Present the data visually using GIS technology so that it is useful for SOS Tobago

to use it in their monitoring and future research

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Materials and Methods

Location of Study Sites

All research was carried out on the Island of Tobago in collaboration with Save Our Sea

Turtles Tobago. Data was collected from three index beaches; Turtle Beach, Grafton and

Mt. Irvine Back Bay, as can be seen in Figure 2. These beaches are patrolled every year

by SOS.

Figure 2: A map of Tobago showing the location of the study sites around the island. Retrieved from the worldwide web 2010 from www.grangecottagetobago.com/tobago.html

Data on nesting turtle numbers was also collected from other (non-index) beaches

around the island, most of which had seldom previously been studied. These beaches

included Englishman’s Bay, Parlatuvier, Dead Bay, Bloody Bay, Argyle (Carapuse Bay),

Fort Granby, Minister’s Bay (Big Bacolet), Lambeau, Crown Point, Kilgwyn Bay and Sandy

Point, as seen in Figure 2. These beaches are described in detail later on in this project.

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Data collection on nesting turtles

Materials used:

Data collection sheets and pen

Global Positioning System (GPS)

Measuring tape

Latex Gloves

Bags for nest relocation

Head torch with red filter

Flipper tags and PIT tags with tagging device

The three index beaches were patrolled at night between the hours of 8pm and 6am

every day of the week between the 1st of March and the 30 th of September 2010. This

was done by two groups of volunteers, with one group covering Turtle Beach and the

other patrolling both Grafton and Mt. Irvine Back Bay. Beaches were patrolled at 30

minute intervals, ensuring a regular SOS presence to dissuade illegal poaching and also

ensuring that all turtles were encountered during an early stage of the laying process.

When a turtle or turtle tracks were encountered, a data sheet (Figure 3, Appendix) was

filled in. Only fresh nests were recorded. On the first patrol all nests found were

recorded. On the second patrol GPS prevented the same nests being recorded. It was

relatively easy to identify the turtle nests. Although turtles camouflage it was possible to

see disturbance in the sand and turtle tracks going to and from the nest. It was also

relatively easy to distinguish between species. The tracks of a leatherback were wider

and the flipper marks were symmetrical. Hawksbill tracks were much narrower and the

flipper marks were asymmetrical. If a turtle was seen the species of turtle, time seen,

weather and beach were noted. The patrol members would then sit down on the beach,

far enough from the turtle so as not to disturb it but to still allow monitoring. Once a

turtle deposited 10 or so eggs they would reach a trance-like state from which they

could not be disturbed. It was then that data collection would begin by shining a red

light on the posterior end of the turtle and checking for identification tags. Tag numbers

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where present were recorded. When no tag was present one was applied to the flap of

skin between the tail and the rear flipper, on each side. A Passive Integrated

Transponder (PIT) tag was inserted into the front right shoulder, if the patrol carried the

equipment to do so. Measurements of the carapace were taken using a 2m flexible

measuring tape. Length was measured keeping the measuring tape as close to the

longitudinal central ridge on the carapace as possible, running from just behind the

turtles head to the posterior tip. The breadth was measured at the widest point from

the lateral ridges, the measuring tape perpendicular to the longitudinal central ridge.

Any distinguishing features such as bite marks or damaged carapace were noted. The

GPS location of the nest was taken to prevent double counting of nests and the beach

zone was recorded. When the turtle had finished laying the outcome and time of entry

back into the sea was noted. If the turtle became confused by lights, people or dogs this

was also recorded. On occasion turtle tracks were encountered after the turtle had

returned to sea. These were classed as estimated lays or unknowns if patrollers were

unsure about the outcome.

The more non-index beaches were patrolled in the daytime between the hours of 7am

and 5pm from the 16th of June until the 5th of August in the following order:

Englishman’s Bay, Parlatuvier, Bloody Bay, Dead Bay, Argyle, Fort Granby, Minister’s Bay

(otherwise known as Big Bacolet), Lambeau, Kilgwyn, Crown Point and Sandy Point. A

car was used for transport between the beaches and the patrols occurred once a week

on a Tuesday where possible. The team of four people included an expert on Tobago’s

sea turtles. When turtle tracks were encountered the data was collected the same as on

the index beaches using a data sheet (Figure 3, Appendix).

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Beach profiling

Materials used for beach profiling:

Measuring Tape

Abney level

Compass

Data collection sheet and pen

Camera

Global Positioning System (GPS)

Two researchers (Person A and Person B)

The beaches were profiled using the WWF Beach Profiling Manual (Fish, 2011) as a

guide between 16th June and the 5th August 2010. Across the width of the beach,

sampling points 50m apart were measured. From these points the length of the beach

was profiled, with the profile being perpendicular to the water, as seen in Figure 4.

Figure 4: A diagrammatic picture showing beach profiling. Constructed using Adobe Photoshop.

Two people were required to profile the beaches, labelled person A and person B for

clarity. The eye level of person A was determined on person B by standing side by side

and noting where, on person B, person A’s eye level was. Person A then stood at the top

of the sampling point with the Abney level, GPS and compass, and person B stood at the

bottom of the sampling point. The compass bearing of the profile was measured and the

GPS was used to record the starting point. Starting from person A at the top of the

beach person B then stood at the next point of change in slope as seen in Figure 5.

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Figure 5: A diagram showing the beach profiling. Taken from WWF Profiling Manual (Fish, 2011).

The Abney level was used by lining the eye piece mark up with the eye level determined

on person B. The level was measured by moving the bubble to the centre of the mark on

the eyepiece. The distance between person A and person B was measured and recorded

along with the slope taken from the Abney level. This process was continued at the next

change in slope, with person B moving down to the next point of change in the slope,

and person A moving to the point previously occupied by person B. After the whole

sampling point had been measured person A and B moved to the next sampling point

50m along the beach and repeated the process.

Mapping

The initial plan was to use GIS technology to present the data. However in the end this

route was not possible and so Google Earth and Bing Maps were used to present the

data. Google Earth had only parts of the island available to view in detail and so Bing

maps had to be used to view some of the beaches. However to be able to input the data

into Bing Maps a demo version of software had to be used. This means that the maps

have the words ‘staging’ printed across them.

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Statistical Analysis

The false crawl results were analysed using a General Linear Model in Minitab 15

Statistical Software. Data first had to undergo Arcsine Transformation before entry into

Minitab.

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Results

Leatherback turtles

Nesting

Number of nests and false crawls were collected nightly from the three index beaches

between the dates of 1st March and 30th September (Table 1). Turtle Beach had the

highest nesting activity.

Table 1: Nesting numbers of leatherback turtles on index beaches.

Beach Nests False crawls Unknown

Turtle Beach 264 45 1

Grafton 63 45 5

Back Bay 99 22 7

Data were collected weekly during daylight hours from eleven non-index beaches

between 16th June and 5th August. These results are presented in Table 2 along with the

nightly data for this time period from the index beaches. There was also one recorded

stranding of a leatherback on Mt. Irvine Back Bay, which later returned to sea.

There was a significant number of turtle emergences on non-index beaches which were

classed as ‘unknown`, i.e. turtle tracks which could not definitely be classed as either a

false crawl or confirmed nest. An average false crawl rate from the index beaches, 2005

to 2010 was calculated to be 16.7%. This was applied to the unknown data, therefore

assuming that 16.7% of the emergences listed as unknowns would be classed as false

crawls and 83.3% as nesting events. This can be seen in Table 2 under the heading

‘Edited Nests`, which is the total of confirmed nests plus the proportion of likely nests

calculated from the unknowns.

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Table 2: Nesting numbers of leatherback turtles on index and non-index beaches.

Beach Coast Nests False crawls Unknown Edited Nesting

Turtle Beach Caribbean 96 14 1 97

Grafton Caribbean 30 18 2 32

Mt. Irvine Back Bay Caribbean 36 5 0 36

Englishman's Bay Caribbean 4 1 5 8

Parlatuvier Caribbean 2 1 2 4

Bloody Bay Caribbean 6 3 15 18

Dead Bay Caribbean 10 3 10 18

Argyle Atlantic 0 0 0 0

Fort Granby Atlantic 0 0 0 0

Ministers Bay Atlantic 0 1 5 4

Lambeau Atlantic 0 0 0 0

Kilgwyn Atlantic 0 0 0 0

Crown Point Atlantic 0 0 0 0

Sandy Point Atlantic 0 0 0 0

Total 217

In the above table the first seven nests are located on the Caribbean coastline. The last

seven nests are located on the Atlantic coastline. There is a total of 217 nests in the

Edited Nesting column. From this it was calculated that 98% of leatherback turtles nest

on the Caribbean coastline of Tobago compared with only 2% on the Atlantic coastline

during this time period.

False Crawls

By analysing data from 1st March to 30th September, 2005 to 2010 on index beaches an

average false crawl rate for leatherback turtles was 16.7%. However, the false crawl rate

varied depending on the beach, for example in 2010 the average false crawl rate on

Grafton Beach is 37.7%, whereas on Mt. Irvine Back Bay it is only 15%. There are also

fluctuations between years. Interestingly in 2006 on Mt. Irvine Back Bay there is an

average false crawl rate of 0%. This can be seen in Table 3.

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Table 3: Average leatherback false crawl rates in % for each beach per year.

Beach 2005 2006 2007 2008 2009 2010

All Beaches 5.5 7.8 19.8 15 27.4 24.8

Turtle Beach 4.3 11.5 15.1 3.5 16.6 14.6

Grafton 7.9 11.8 8.3 23.4 38.2 41.7

Mt. Irvine Back Bay 4.2 0 36 18 27.4 18.2

When in the form of a graph (Figure 6), it is easy to see that there is a general increase

in false crawl rates from 2005 to 2010, particularly in the case of Grafton. In 2007 there

is a large increase in the rate of false crawls on Mt. Irvine Back Bay.

Figure 6: A graph showing the % false crawl rates for leatherbacks for different beaches (N=2159).

0

10

20

30

40

50

2005 2006 2007 2008 2009 2010

Average %

Year

Average % of false crawls in leatherbacks per beach per year

TurtleBeach

Grafton

Mt. IrvineBack Bay

The results were input into Minitab using a General Linear Model and it was found that

the differences in false crawl rates between beaches were not significantly different

from each other (F=1.26, DF=2, P=0.324) or years (F=2.22, DF=5, P=0.133). Therefore an

average false crawl rate for the index beaches is a valid figure to use for the correction

of the unknowns.

23

Beach Profiling

All the beaches that were surveyed were also profiled with the intention of creating a

visual diagram of the profile of each beach and comparing the profile with the number

of turtles nesting on the beach. However due to lack of specific software required for

this it was not possible to do so. Instead, the average slope gradient for each beach was

calculated, as seen in the previous section. Leatherback nesting density was calculated

using edited turtle nesting numbers from Table 1 and the % of leatherback turtles

nesting on each beach was calculated using data between 16th June and 5th August

(Table 4). Nesting density is based on the number of nests per beach divided by the area

(m²).

Table 4: Summary of beach profiling data, including % of leatherback turtles nesting on beaches and

leatherback nesting density.

Beach Length (m)

Breadth (m)

Area (m²)

Slope over entire beach

(degrees)

slope nearest

sea edge (degrees)

% Nesting

Number of nests

Nesting Density

(nests/m²)

Turtle Beach 1210.68 31.3 37894 -5.6 -9.6 45 97 0.0026

Grafton 896.33 29.9 26800 -4.1 -6.6 15 32 0.0012

Mt. Irvine Back Bay 473.8 42 19900 -4.7 -6.2 17 36 0.0018

Englishman's Bay 350 17.34 6069 -9.5 -9.6 4 8 0.0013

Parlatuvier 242.86 29.50 7164 -9.1 -8 2 4 0.0006

Dead Bay 207.23 28 5802 -3.8 -5.2 8 18 0.0031

Bloody Bay 314.90 21.74 6846 -5.1 -7.6 8 18 0.0026

Argyle 1051 14.13 14851 -6.3 -5.9 0 0 0

Fort Granby 647.73 12.56 8135 -5.9 -5.9 0 0 0

Ministers Bay 1300 16.56 21528 -4.1 -4.3 2 4 0.0002

Lambeau 1530 37.50 57375 -1.5 -0.8 0 0 0

Crown Point 320.14 12.30 3938 -3.8 -4 0 0 0

Kilgwyn 200 4 800 -10 -10 0 0 0

Sandy Point 150 8 1200 -7.1 -8.3 0 0 0

In Figure 7 it can be seen that the index beaches are all major nesting sites for the

leatherback, Turtle Beach in particular.

24

Figure 7: The % of leatherbacks nesting on beaches.

Hawksbill Turtles

Nesting

Data were collected nightly from index beaches between the dates of 1st March and 30th

September (Table 5). On the 28th July a hawksbill turtle was found dead from poaching

on Grafton Beach.

Table 5: Nesting numbers of hawksbill turtles on index beaches.

Beach Nests False crawls Unknown

Turtle Beach 7 6 0

Grafton 4 7 0

Mt. Irvine Back Bay 13 3 0

Data were collected nightly from three index beaches and weekly during daylight hours

from eleven non-index beaches between 16th June and 5th August (Table 4). On the 22nd

June a local on Englishman’s Bay alerted the patrol to hawksbill turtle tracks where the

tracks led up to a body pit with none leaving. From the body pit evidence could be seen

25

where the turtle was dragged on its back to tyre marks. It can be assumed from this that

the hawksbill turtle was poached.

There was a large number of turtle nestings on non-index beaches that were classed as

unknown when they were recorded. The average false crawl rate from the index

beaches, 2005 to 2010 was 25%. This was applied to the data, assuming that 25% of the

unknowns were false crawls and 75% as nesting events. This can be seen in Table 6

under the heading ‘Edited Nests`.

Table 6: Nesting numbers of hawksbill turtles on index and non-index beaches.

Beach Coast Nests False crawls Unknown Edited Nests

Turtle Beach Caribbean 3 4 0 3

Grafton Caribbean 2 7 0 2

Mt. Irvine Back Bay Caribbean 10 1 0 10

Englishman's Bay Caribbean 6 1 7 11

Parlatuvier Caribbean 0 0 0 0

Bloody Bay Caribbean 1 0 0 1

Dead Bay Caribbean 4 0 5 8

Argyle Atlantic 0 0 0 0

Fort Granby Atlantic 0 0 1 1

Ministers Bay Atlantic 4 4 2 6

Lambeau Atlantic 1 0 0 1

Kilgwyn Atlantic 0 0 0 0

Crown Point Atlantic 0 0 3 2

Sandy Point Atlantic 2 0 1 3

Total 48

A total of 48 hawksbill clutches were laid over the 14 surveyed beaches during the time

period of data collection. It was calculated that 74% of hawksbills nest on the Caribbean

coastline compared with 26% on the Atlantic coastline.

False Crawls

By analysing data from 2005 to 2010 on index beaches an average false crawl rate of

25% was found in hawksbills. The false crawl rate varied depending on the beach, for

example in 2010 the average rate is 63.6% on Grafton but only 18.8% on Mt. Irvine Back

26

Bay. There were large fluctuations between beaches and years, perhaps due to small

sample size (Table 7).

Table 7: Average hawksbill false crawl rates in % for each beach per year.

Beach 2005 2006 2007 2008 2009 2010

All Beaches 12.2 26.9 33.3 8.3 26.2 42.9

Turtle Beach 16.7 55.6 0 0 28.6 46.2

Grafton 0 0 0 25 33.3 63.6

Mt. Irvine Back Bay 20 25 100 0 16.7 18.8

In the form of a graph, as seen in Figure 8, it can be seen that there are large

fluctuations in false crawl % rates between years however there does seem to be a

general increase in false crawl rates form 2005 to 2010. From 2008 onwards there is a

steady increase in the rate of false crawls every year. Similar to the leatherback false

crawl rates, there is a large increase in 2007 on Mt. Irvine Back Bay.

Figure 8: A graph showing the % false crawl rates for hawksbills for different beaches (N=116).

0

20

40

60

80

100

2005 2006 2007 2008 2009 2010

Average %

Year

Average % of false crawls in hawksbill per beach per year

Turtle

Beach

Grafton

Mt. IrvineBack Bay

The results were input into Minitab using a General Linear Model and it was found that

the differences in false crawl rates between beaches were not significantly different

from each other (F=0.2, DF=2, P=0.824) or years (F=0.45, DF=5, P=0.8

27

Beach Profiling

All the beaches that were surveyed were also profiled with the intention of creating a

visual diagram of the profile of each beach and comparing the profile with the number

of turtles nesting on the beach. However due to lack of specific software required for

this it was not possible to do so. Instead, the average slope gradient for each beach was

found. Hawksbill nesting density was calculated using edited turtle nesting numbers

from Table 6 and the % of hawksbill turtles nesting on each beach was calculated using

data between 16th June and 5th August (Table 8).

Table 8: Summary of beach profiling data, including % of hawksbill turtles nesting on beaches and

hawksbill nesting density.

Beach Length Area

Slope over entire beach

(degrees)

slope nearest

sea edge (degrees)

Number of nests

% Nesting

Nesting Density

Turtle Beach 1210.68 37894 -5.6 -9.6 3 6 0.00008

Grafton 896.33 26800 -4.1 -6.6 2 4 0.00007

Mt. Irvine Back Bay 473.8 19900 -4.7 -6.2 10 21 0.00050

Englishmans 350 6069 -9.5 -9.6 11 23 0.00181

Parlatuvier 242.86 7164 -9.1 -8 0 0 0

Dead Bay 207.23 5802 -3.8 -5.2 8 17 0.00138

Bloody Bay 314.90 6846 -5.1 -7.6 1 2 0.00015

Argyle 1051 14851 -6.3 -5.9 0 0 0

Fort Granby 647.73 8135 -5.9 -5.9 1 2 0.00012

Ministers Bay 1300 21528 -4.1 -4.3 6 13 0.00028

Lambeau 1530 57375 -1.5 -0.8 1 2 0.00002

Crown Point 320.14 3938 -3.8 -4 2 4 0.0005

Kilgwyn 200 800 -10 -10 0 0 0

Sandy Point 150 1200 -7.1 -8.3 3 6 0.00250

Englishman’s Bay, Mt. Irvine Back Bay, Dead Bay and Minister’s Bay are all important

nesting sites for the hawksbill (Figure 9).

28

Figure 9: The % of hawksbills nesting on beaches.

Mapping

Bing Maps and Google Earth were used to form satellite images of the beaches showing

turtle nesting sites, both hawksbill and leatherback. A GPS was used to record nesting

sites. However in some cases due to a bad signal and the inaccuracy of a GPS, nesting

sites may be recorded around 5 metres away from their actual location, as can be seen

in the maps where nesting points are recorded close to the water or amongst the trees.

The data seen in the maps consists of all turtle nesting events (both hawksbill and

leatherback) including false crawls from 16th June to the 5th August. In some of the maps

the turtle nesting numbers may not match tables due to GPS coordinates missing from

the occasional event.

29

Below, in Map 1, is an image of Mt. Irvine Back Bay showing the nesting sites of turtles

on the beach.

Map 1: A satellite image of Mt. Irvine Back Bay, located on the Caribbean coastline, with green markers

representing leatherback nesting events and red markers representing hawksbill nesting events. Formed

using Google Earth, thirty-four of the points are leatherback nests, eight are hawksbill.

Mt. Irvine Back Bay is 474 meters in length and has an average breadth of 42 meters.

The beach tends to be relatively flat at the tree line and slope more steeply towards the

water edge. The average slope near the tree line is -2.1° whereas the slope at the sea

edge has an average of -6.2°. The overall average slope over the breadth of the beach is

-4.7°. There is plenty of plant life at the back of the beach, with sand found stretching

back into the tree line. There is an area of rock found in the centre of the beach and at

one end but there are large stretches of beach free from any rocky outcrops. There is

little or no light or noise pollution due to the secluded location of the beach.

30

Below, in Map 2, is an image of Grafton showing the nesting sites of turtles on the

beach.

Map 2: A satellite image of Grafton, located on the Caribbean coastline, with green markers representing

leatherback nesting events and red markers representing hawksbill nesting events. Formed using Google

Earth, Twenty-eight of the nesting events are leatherback and seven hawksbill.

Grafton is 896 meters in length and has an average breadth of 30 meters. The beach

tends to be relatively flat at the back of the beach and slopes more steeply near the sea

edge. The average slope near the back of the beach is -2.1° whereas the slope at the sea

edge has an average of -6.6°. The overall average slope over the breadth of the beach is

-4.1°. Grafton is a popular beach with tourists and locals and as such many objects such

as sun-loungers, tables and litter are frequently encountered. The light pollution on this

beach is the highest of the three index beaches, coming from hotel spot lights and

roadside street lamps. There is also noise pollution from traffic and loud music. During

the day the beach is commonly used for water sports such as jet skiing, scuba diving and

kayaking. At the back of the beach there is some vegetation in the form of trees and

31

small bushes. Along the length of the beach are several drains, causing pools of

stagnant, unclean water. On occasion turtles will become stranded in these pools,

unable to escape them due to the steep sides.

32

Below, in Map 3, is an image of Turtle Beach showing the nesting sites of turtles on the

beach.

Map 3: A satellite image of Turtle Beach, located on the Caribbean coastline, with green markers

representing leatherback nesting events and red markers representing hawksbill nesting events. Formed

using Google Earth, with 81 counts of leatherback nesting events and five hawksbill.

Turtle Beach is 1211 meters in length and has an average breadth of 31 meters. The

beach tends to be almost flat at the back of the beach and slopes very steeply at the

water’s edge. The average slope near the back of the beach is -1.8° whereas the slope at

the sea edge has an average of -9.6°. The overall average slope over the breadth of the

beach is -5.6°. Turtle Beach, like Grafton, is popular with tourists. Sun-loungers, tables,

litter and parasols are commonly found. There is a fishery based on the beach with nets

and small boats found on the beach regularly. During the day there is often jet skiing

and kayaking in the water. Along the back of the beach in some areas it is highly

developed with little vegetation and often the top of the beach meets stone walls or

hotels. In other areas there is lots of vegetation at the back of the beach. There are two

33

rivers that cross the beach, one at the Northern end and one at the Southern end of the

beach. There is light pollution from hotel spotlights and often noise pollution from

people, loud music and traffic.

34

Below, in Map 4, is an image of Englishman’s Bay showing the nesting sites of turtles on

the beach. The word ‘Staging` that is present on the map is a watermark present on all

Bing Maps and is not significant. It was not possible for these maps to separate

leatherback and hawksbill nesting events and so the number of each is stated in the

map description below.

Map 4: A satellite image of Englishman’s Bay, located on the Caribbean coastline, with turtle nests

represented by the yellow spots, formed from Bing Maps. Fifteen of the points are leatherback nesting

events, ten are hawksbill.

Englishman’s Bay is 350 meters in length and has an average breadth of 17 meters. The

beach tends to slope steeply from the back of the beach, continuing to the sea. The

average slope from the back of the beach is the same as the average slope from the sea

edge at -9.6°. The overall average slope over the breadth of the beach is -9.5°.

Englishman’s Bay is relatively secluded with little or no light or noise pollution at night.

The back of the beach is covered with vegetation on one side and rocks on the other.

35

Below, in Map 5, is an image of Parlatuvier showing the nesting sites of turtles on the

beach.

Map 5: A satellite image of Parlatuvier, located on the Caribbean coastline, with turtle nests represented

by the yellow spots, formed from Bing Maps. All five points are leatherback nesting events.

Parlatuvier is 243 meters in length and has an average breadth of 30 meters. The beach

tends to have a relatively steep slope at the back of the beach, becoming slightly

steeper at the water’s edge. The average slope near the back of the beach is -7.7° and

the slope at the sea edge has an average of -8°. The overall average slope over the

breadth of the beach is -9.1°. Parlatuvier is used often for fishing with many nets

covering the beach and a long pier with many boats in the water. There is very little

vegetation at the back of the beach due to development although there are some small

bushes and grasses present. There may be some light pollution due to the proximity of

buildings.

36

Below, in Map 6, is an image of Dead Bay showing the nesting sites of turtles on the

beach.

Map 6: A satellite image of Dead Bay, located on the Caribbean coastline, with turtle nests represented by

the yellow spots, formed from Bing Maps. Twenty-three of the points are leatherback nesting events, nine

are hawksbill.

Dead Bay is 207 meters in length and has an average breadth of 28 meters. The beach

tends to slope gently at the tree-line becoming steeper towards the water’s edge. The

average slope near the back of the beach is -3.3° whereas the slope at the sea edge has

an average of -5.2°. The overall average slope over the breadth of the beach is -3.8°.

Dead Bay is very secluded with a forest track and steep cliff track leading to the beach.

There is a river running down the beach which tends to vary in the path it cuts across

the beach. There would be no light or noise pollution on the beach at night due to its

remote location.

37

Below, in Map 7, is an image of Bloody Bay showing the nesting sites of turtles on the

beach.

Map 7: A satellite image of Bloody Bay, located on the Caribbean coastline, with turtle nests represented

by the yellow spots, formed from Bing Maps. Twenty-four of the points are leatherback nesting events,

one is hawksbill.

Bloody Bay is 315 meters in length and has an average breadth of 22 meters. The beach

tends to slope gently at the tree line, becoming steeper towards the water’s edge. The

average slope near the back of the beach is -2.3° whereas the slope at the sea edge has

an average of -7.6°. The overall average slope over the breadth of the beach is -5.1°. Due

to construction work Bloody Bay is covered in many small boulders and car tracks were

frequently seen on the beach. There was limited vegetation at the back of the beach but

there were some grasses. At night there would be little or no light or noise pollution due

to the secluded location of the beach.

38

Below, in Map 8, is an image of Argyle.

Map 8: A satellite image of Argyle, located on the Atlantic coastline, formed from Bing Maps. There were

no recordings of turtle tracks on this beach.

Argyle is 1051 meters in length and has an average breadth of 14 meters. The beach

tends to slope from the tree line to the water’s edge with little difference in the slope,

becoming slightly less steep towards the water’s edge. The average slope near the back

of the beach is -6.6° whereas the slope at the sea edge has an average of -5.9°. The

overall average slope over the breadth of the beach is -6.3°. The beach is long and

narrow with tides reaching the vegetation line at the back of the beach. There may be

some light pollution at night due to proximity of hotels and buildings.

39

Below, in Map 9, is an image of Fort Granby showing the nesting sites of turtles on the

beach.

Map 9: A satellite image of Fort Granby, located on the Atlantic coastline, with turtle nests represented by

the yellow spots, formed from Bing Maps. The only instance of turtle nesting events on this beach is

hawksbill.

Fort Granby is 648 meters in length and has an average breadth of 13 meters. The beach

tends to slope steeply at the tree-line, becoming only slightly less steep towards the

water’s edge. The average slope near the back of the beach is -6.8° whereas the slope at

the sea edge has an average of -5.9°. The overall average slope over the breadth of the

beach is -5.9°. Fort Granby Bay is similar to Argyle in that it is long and narrow with a

steeper slope towards the back of the beach and in that the tides come up high, often

covering the entire beach. There is little or no light or noise pollution at night due to the

secluded location of the bay.

40

Below, in Map 10, is an image of Minister’s Bay showing the nesting sites of turtles on

the beach.

Map 10: A satellite image of Minister’s Bay, located on the Atlantic coastline, with turtle nests

represented by the yellow spots, formed from Bing Maps. Six of the points are leatherback nesting events,

ten are hawksbill.

Minister’s Bay is 1300 meters in length and has an average breadth of 16.56 meters. The

beach tends to slope gently at the tree-line, with only a very slight change in slope

towards the water’s edge. The average slope near the back of the beach is -4° whereas

the slope at the sea edge has an average of -4.3°. The overall average slope over the

breadth of the beach is -4.1°. Ministers Bay experiences high tides, which regularly reach

the tree-line. Most of the beach would be unaffected by light or noise pollution but

there is some nearby housing which could pose some light pollution.

41

Below, in Map 11, is an image of Lambeau showing the nesting sites of turtles on the

beach. There was one instance during data collection where the tracks of hatchlings

were found and the nest was located. Other than this case no other instances of nesting

was recorded.

Map 11: A satellite image of Lambeau, located on the Atlantic coastline, with turtle nests represented by

the yellow spots, formed from Google Earth. The only instance of turtle nesting was hawksbill.

Lambeau is 1530 meters in length and has an average breadth of 38 meters. The beach

tends to slope very gently, with a slight decrease in slope towards the water’s edge. The

average slope near the back of the beach is -2.1° whereas the slope at the sea edge has

an average of -0.8°, almost horizontal. The overall average slope over the breadth of the

beach is -1.5°. On this beach tides cover the breadth of the beach regularly. There is

vegetation at the back of the beach including trees, bushes and grasses. There may be

some light pollution at night due to the proximity of hotels and buildings.

42

Below, in Map 12, is an image of Crown Point showing the nesting sites of turtles on the

beach.

Map 12: A satellite image of Crown Point, located on the Atlantic coastline, with turtle nests represented

by the yellow spots, formed from Google Earth. All instances of turtle nesting events were hawksbill.

Crown Point is 320 meters in length and has an average breadth of 12 meters. The

beach tends to slope gently at the tree-line, becoming only slightly steeper towards the

water’s edge, with very little difference in slope along the breadth of the beach. The

average slope near the back of the beach is -3.8° and the slope at the sea edge has an

average of -4°. The overall average slope over the breadth of the beach is -3.8°. At the

back of the beach there are large amounts of vegetation. The tide reaches high on the

beach, regularly meeting the tree-line and covering the entire breadth if the beach.

Crown Point is located extremely close to the airport and as such would receive high

levels of light and noise pollution.

43

Below, in Map 13, is an image of Kilgwyn. There was no evidence of turtle nesting

events on the beach during data collection.

Map 13: A satellite image of Kilgwyn, located on the Atlantic coastline, formed from Google Earth.

Kilgwyn is 200 meters in length and has an average breadth of 4 meters. The beach

tends to slopes very steeply with just one slope maintained along the 4 metres and no

change in slope. The overall average slope over the breadth of the beach is -10°. Kilgwyn

Bay is located very near to the airport, which is found just outside the top edge of Map

13. As such the bay may experience light and noise pollution. Vegetation is found in

large amounts in the form of trees and bushes at the top of the beach. Tides regularly

reach the tree-line covering the entire breadth of the beach.

44

Below, in Map 14, is an image of Sandy Point showing the nesting sites of turtles on the

beach.

Map 14: A satellite image of Sandy Point, located on the Atlantic coastline, with turtle nests represented

by the yellow spots, formed from Google Earth. All instances of turtle nesting were hawksbill.

Sandy Point is 150 meters in length and has an average breadth of 8 meters. The beach

tends to slope steeply at the tree-line, becoming steeper towards the water’s edge. The

average slope near the back of the beach is -6° and the slope at the sea edge has an

average of -8.3°. The overall average slope over the breadth of the beach is -7.1°. Sandy

Point is located next to the airport runway and as such may receive high levels of light

and noise pollution. The beach has large amounts of vegetation at the back in the form

of large bushes. It is popular with people as it is easy to access from the road.

45

Limitations in Data Collection

There are some recognised limitations in the data collection methods used for this

project. During the data collection on non-index beaches, it was possible there could

have been some variation in effort and surveyor experience. During the profiling and

surveying there were always two people who carried out the work every week, myself

and an experienced observer, Giancarlo Lalsingh, who was the only person to decide the

category of the nesting event. The two helpers for beach profiling changed most weeks,

but I was there to oversee procedures and ensure they remained the same in each case.

In data collection for the non-index beaches the observers varied, with different groups

on different beaches every night, however there was always an experienced leader in

the group to ensure data collection was carried out correctly.

In surveying the non-index beaches the aim was to patrol every beach each week.

However sometimes this was not possible. On occasion, bad weather conditions would

prevent this by making roads impassable, and conditions dangerous in the case of

lightning storms. On others high tides meant that only parts of some beaches could be

surveyed due to access. The beaches were surveyed as often as possible keeping in

mind the health and safety of the team. The circumstances during weeks of patrols can

be seen below in Table 8. The circumstances are stated as ‘possible` to patrol, ‘not

possible` to patrol or the patrol was ‘not completed`.

46

Table 8: Showing when and where patrols took place on non-index beaches.

Beaches Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8

Englishman's Bay Possible Possible Possible

Not Possible Possible Possible Possible Possible

Parlatuvier Possible Possible Possible Not Possible Possible Possible Possible Possible

Bloody Bay Possible Possible Possible Not Possible Possible Possible Possible Possible

Dead Bay Possible Possible Possible Not Possible Possible Possible Possible Possible

Argyle Possible Not Completed Possible

Not Possible Possible

Not Completed Possible

Not Completed

Fort Granby Possible Possible Possible Not Possible Possible Possible Possible Possible

Ministers Bay Possible Possible Possible Not Possible

Not Possible Possible Possible Possible

Lambeau Possible Possible Possible Not Possible

Not Possible Possible Possible Possible

Kilgwyn Possible Possible Possible Not Possible

Not Possible Possible Possible Possible

Crown Point Possible Possible Possible Not Possible

Not Possible Possible Possible Possible

Sandy Point Possible Possible Possible Not Possible

Not Possible Possible Possible Possible

The turtle nesting season occurs during the rainy season in Tobago. Often there would

be heavy rainfall. There were some concerns that this would cause turtle tracks and

nesting behaviour to be washed away. Although the condition of the nests did

deteriorate over the weeks, generally, despite heavy rain, the tracks were still able to be

observed. This was not the case on beaches where high tides washed away all evidence

of turtle nesting behaviour.

Species identification errors may occur in cases where tracks are particularly

deteriorated or data collectors are relatively in-experienced however the tracks of

different species are distinct enough that this would be a rare occurrence and not

enough to cause significant effects on the results.

47

During daylight surveys of non-index beaches it was always the case that turtle tracks

were encountered rather than the turtles themselves. Often it was difficult to determine

the outcome of tracks and so they were identified as unknown. This became confusing

when evaluating the data as such a large amount of the data was classed under this

category.

48

Discussion

Leatherback

Sea Turtle Nesting Behaviour

In Table 1 it can be seen that there are a significant number of leatherback turtle nests

recorded in Tobago, with 426 confirmed nests in the season over the three index

beaches. Previous research has stated that Trinidad and Tobago support the second

largest nesting group of leatherback in the western hemisphere (Lum, 2005).

In Table 2 it can be seen that the three index beaches have the largest numbers of

leatherbacks nesting on them, Turtle Beach in particular is a key nesting site. This may

be due to the nesting preferences of the species. Leatherbacks tend to prefer beaches

with a deep approach, high wave energy and a steep front (Livingstone, 2006). The

three main index beaches are all long, open and relatively wide, all features that

leatherbacks prefer (Nordmoe et al, 2004). It may be that the index beaches on Tobago

are more suited to the larger, more cumbersome leatherback turtle.

In this study it was found that 98.4% of leatherback nest on the Caribbean coastline and

only 1.6% on the Atlantic coastline. The Caribbean coast of Tobago is more sheltered

and protected from exposure and erosion than the Atlantic coast. In the study by

Horrocks and Scott (1991) they found that the beaches on the west coast in Barbados

tended to be steeper in slope on emergence from the water than east or south coast

beaches. From this study the results were similar in that the Caribbean coastline had an

average gradient of -7.5 near the sea edge as compared to -5.6 on the Atlantic coastline.

With leatherbacks preferring a steep gradient on emergence from the sea this could be

another reason as to why turtles choose to nest mainly on the Caribbean coastline. A

previous study by Cawley (2005) found the Atlantic coast of Tobago to be far more

populated and under more development than the Caribbean coast. One of the main

roads is found on the Atlantic side of the island, often running close to beaches. There

was evidence of sand mining in 2005 on the beaches on this side of the island and there

49

was evidence still in 2010 on Fort Granby (Cawley, 2005). Both development and sand

mining leads to flatter beaches, with less vegetation and less suitable substrate for

nesting, perhaps the reason for fewer nests on the Atlantic Coast.

With leatherback turtles nesting on three main beaches on Tobago this makes

monitoring them relatively easy. By patrolling only the three main index beaches nearly

all of the leatherback turtle nesting population of Tobago can be covered. This means

that fewer resources such as time and money are required to ensure the conservation

and research of this species on Tobago.

False crawls

A false crawl rate was used in the results to determine how likely the recorded unknown

nesting behaviour was to be either a false crawl or a nesting attempt. The false crawl

rates were not found to be significant and this may be due to small sample size.

Certainly in the case of 0% false crawl rate in 2008, there were only 16 leatherbacks that

nested on the beach that year, none of which false crawled. However the average false

crawl rates that were calculated fit well within other false crawl rates found in previous

studies.

For leatherback the average false crawl rate for all index beaches from 2005 to 2010

was 16.7%. A study by Livingstone (2006) found false crawl rates to vary between 8.3%

and 24.9% with a mean of 11.8% over five beaches whilst another study found false

crawl rates to vary between 16% and 25% (Tucker, 1988). A study by Hilterman and

Goverse (2003) found that leatherbacks had a false crawl rate ranging from 8% to 16%.

Another study found that leatherback false crawls are relatively rare, usually under 10%

(Schroeder and Murphy, 1999). Yet another study found leatherback false crawl rates to

be 17.78% (Gaos et al, 2006).

50

From 2005 to 2010 the average leatherback false crawl rate seems to undergo a general

increase each year, from 5.5% in 2005 to 22.1% in 2010. Grafton in particular has a high

increase over the years. It is hard to tell if this increase in false crawl rates is due to an

increase in patrol effort or due to an increase in development and Tobago’s popularity

as a tourist resort. Patrol effort from SOS Tobago has increased over the last 5 years,

with an increase in numbers of patrollers available and hours spent patrolling. Initially

patrols began at 9pm and ended at 2am at the beginning of the season in 2005, moving

to 3am during peak nesting season. However in 2010 this had increased to beginning at

8pm and ending at 4am, with morning walks until 6am also included during peak season

(Lalsingh, 2010, Clovis, 2005). The increase in false crawl rate could also be due to the

development of hotels, beach lighting and an increase in use by people. Tobago is

becoming an increasingly popular tourist resort and there is more development on

beaches and beach fronts as a result.

There are many factors that may cause sea turtles to false crawl, some of them

unknown. The presence of people and predators can cause turtles to false crawl as can

light or noise. Grafton and Turtle Beach experience both light and noise pollution, with

people and dogs common on the beach at night. Grafton in particular experiences very

high levels of light and noise pollution along the majority of the beach. The light

pollution comes from hotels and building spot lights, the noise pollution from loud

music being played most nights from a bar found at the tree line of the beach. Grafton

had the highest false crawl rates for leatherbacks in every year, except in 2007 where it

was Mt. Irvine Back Bay. These results show that although light and noise pollution may

be a strong influencing factor in the rate of false crawls it is not the only one.

In 2007 there was a particularly high rate of false crawls for leatherback turtles on Mt.

Irvine Back Bay. This beach is highly dynamic in terms of erosion and sand movement

and it may be that in 2007 the profile of the beach was simply unsuitable for nesting.

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When a female nests large amounts of valuable energy are required to drag her body up

the beach and down the beach. When disturbed she may false crawl up to several time

in one night, preventing her from nesting and using up this valuable energy.

Interestingly in a masters project it was found that loggerhead female turtles face

increased stress levels following a false crawl and due to this she is more at risk of being

struck by boats, leading to injury or even death (Sobin, 2008).

Because of this false crawls are a particularly important aspect of turtle nesting

behaviour. Not only does an increase in false crawl rates use up large amounts of

valuable energy and lead to an increased risk of injury and death but they may also

indicate the suitability of a beach for nesting. They can be studied over a period of years

to see if there are changes in characteristics of a beach, for instance an increased

presence of people or changes in profile. The rate of false crawl may also indicate the

effects of beach front development. It would be interesting to study the false crawl

rates further and to look at the effect of light and noise pollution on false crawls. Due to

the false crawl rates in this study not being significant no conclusions can be drawn

about the effect of lighting on sea turtle nesting behaviour. The three index beaches

have different levels of light pollution with Grafton receiving the highest levels and Mt.

Irvine Back Bay receiving almost no light pollution. Further research could use these

beaches to look at the relationship between light pollution and nesting behaviour.

Population Model

One of the aims of the project was to use a population model to estimate the number of

sea turtles that nest on Tobago. Unfortunately it was not possible to complete this as

the model was still in the development stages and could not be finished in time. This

could be used in the future to better understand Tobago’s nesting populations.

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The data from the index beaches was suitable to use in the model but data from the

non-index beaches was not partly because of small sample size, and the uncertainty of

the data due to unknowns.

Models are a useful tool for a better understanding of worldwide populations, which is

required in the conservation of the species. Without first having an estimate of sea

turtle populations, it is hard to know to what extent they need protected. By forming

estimates of where turtle nesting populations are highest, conservation and

management plans can be formed to ensure that areas of high numbers have adequate

protection.

Beach Profiling

From Table 4 it can be seen that there are varying degrees of slopes on the beaches

studied from -1.5 on Lambeau to -10 on Kilgwyn. There does not seem to be a pattern in

the overall slope gradient and the percentage of turtles nesting and so although it may

be an influencing factor, it is not the only factor affecting the number of nesting turtles.

Turtle beach is a major nesting site for leatherbacks supporting nearly half of all turtles

nesting on Tobago. There seems to be no significance in the length, area or slope of

turtle beach as many of the other beaches have similar characteristics but fewer or no

turtles nesting on them. Turtle Beach may be a popular nesting site due to the offshore

profile. It has a deep, wide approach and very little in the way of obstructions, ideal for

leatherback turtles.

In the study by Horrocks and Scott (1991) they found that the beaches on the west coast

in Barbados tended to be steeper in slope on emergence from the water than east or

south coast beaches. From this study the results were similar in that the Caribbean

coastline had an average gradient of -7.5 near the sea edge as compared to -5.6 on the

Atlantic coastline. This may be one of the reasons as to why more leatherbacks nest on

the Caribbean coastline as opposed to the Atlantic coastline. A steeper gradient on

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entry to the beach from the water would mean that leatherbacks have less distance to

travel to ensure that the nest is above the water level mark.

There are long term concerns over the ability of beaches to sustain turtle populations

due to the constant development that is occurring along coastlines. It is now understood

that development can have a great impact on turtle survival rates. Harewood and

Horrocks (2008) conducted a study on Barbados to assess the impacts of coastal

development on hatchling success. This is something that affects hatchlings on many

small Caribbean islands, Tobago included. They found that coastal development has a

large impact on the survival rate of hatchlings and can decrease a hatchlings survival

rate significantly. As Tobago becomes more established as a tourist destination the rate

of development can only increase. Development can affect the beach profile

dramatically by causing coastlines to be more susceptible to erosion and extreme

weather. By regular profiling of Tobago’s beaches important characteristics in a turtle

nesting beach can be established. There is a lack of knowledge about what factors of a

beach are important for nesting turtles and so looking at beach profiles in relation to

density could help to improve on this.

Hawksbill turtles

Nesting Behaviour

In Table 1 it can be seen that hawksbill numbers are very low on the three index

beaches, with only 24 recorded nests. Half of these 24 nests are found on Mt. Irvine

Back Bay. This beach is the most isolated of the three and is without light or noise

pollution. Due to its location it is the quietest of the three index beaches in terms of

human disturbance, with no development and very little human presence.

Although turtles do nest on the index beaches their numbers tend to be higher on small

isolated beaches towards the North of the island. These beaches receive fewer numbers

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of visitors and tend to be less developed, as such having more available vegetation

along the back of the beach. These beaches can be seen in Table 2, which shows

hawksbill nests for non-index and index beaches over the same time period. Here it can

be seen that hawksbill nests are generally higher on non-index beaches than index

beaches, excepting Mt. Irvine Back Bay, with 33 confirmed nests and 48 estimated nests

in total. Although offshore coral reefs around Tobago provide excellent feeding grounds

for hawksbill sea turtles, the island does not support a large population of nesting

hawksbills. In 2005 the annual nesting population of hawksbills was estimated to be

between 28 and 47 (Cawley, 2005). Hawksbills nest in over 70 countries, mostly in low

densities. There is large nesting colony found in Australia, however generally hawksbill

turtles nest in low numbers over many countries, the Caribbean included, and the

nesting populations on Tobago do not reach high numbers. However almost half of the

worlds export of turtle shells is thought to originate from the Caribbean and Latin

American region and so there is great need for turtles in this area to be protected and

conserved (Mortimer and Donnelly, 2008). Hawksbill turtles prefer lower wave energy

on isolated beaches. It may be that Tobago’s beaches are in general less sheltered and

more exposed, leading to a lowered preference for nesting in the hawksbill turtle.

It has been found in a previous study on nest site choice of hawksbill turtles in Barbados,

a nearby island, that the west coast beaches are preferred rather than the south or east

coast (Horrocks and Scott, 1991). This was also recorded in Tobago, with 74% of

hawksbill nests found on the north-west Caribbean coastline compared with only 26%

on the south-east Atlantic coastline. This is similar to the leatherbacks, although less

extreme, and the same reasons may apply. It could be that hawksbills prefer the steeper

sloped entry onto the beach that has been recorded on the Caribbean coastline or it

may be due to the high levels of development that are found on the Atlantic coastline,

causing the flightier hawksbill to nest on quieter beaches on the Caribbean coast.

55

Hawksbills tend to nest on many different beaches over the nesting season when

compared to the leatherback. This nesting behaviour of the hawksbill can make them

very difficult to study and also more difficult to protect and conserve. In leatherbacks

most nests are to be found on the three main index beaches, meaning that even with

limited resources, these beaches can be patrolled and the majority of the turtles and

nests protected. In the case of hawksbills there are many different beaches on which

small numbers of nests are present. Unless large resources are available it is very

difficult to patrol these beaches as often as required to collect data and to protect the

turtles and their eggs from poaching. This proves to be a problem on Tobago where

leatherbacks, due to their large size, are often less susceptible to poaching than the

hawksbills. In recent years, when the poaching of a sea turtle occurs on Tobago, it is

most likely to be a hawksbill. They are easier to manoeuvre and carry away and they are

also less protected. Since the index beaches are now carefully and regularly monitored,

this may mean that poachers go to other less protected beaches to look for turtles,

beaches where hawksbills are more likely to nest. Most of the poaching occurring in

recent years is relevant to hawksbills and this may be because most of the turtles

protected on the beaches patrolled are leatherbacks. SOS Tobago have made a start in

conserving sea turtles on Tobago and do the best with what limited resources they

have. The work that they have done has already made a significant difference in

reducing the number of sea turtles poached each nesting season and educating the

public on the status of sea turtles. However their funding is limited and they do not have

the resources to regularly patrol non-index beaches, where it is most needed to

conserve hawksbills.

False crawls

The false crawl rates were not found to be significant and this may be due to small

sample size as hawksbill numbers were very low on the index beaches. For many years

only one or two and occasionally no nests were recorded on index beaches. Generally

where the false crawl rate is 0% there was only one hawksbill nest recorded for the

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beach for the whole season. The hawksbill false crawl rate was higher than the

leatherback false crawl rate at 25%. Hawksbills are known to be more flighty and are

easily disturbed. This is probably due to their small size and manoeuvrability. Being

smaller they will be more susceptible to predators and so are more likely to employ an

escape mechanism by returning to the sea at any sign of disturbance. Indeed in a study

by McIntosh et al (2003) the false crawl rate was found to be as high as 93.8% on one

beach with an average of 56.5% for all beaches. One of the beaches, the least developed

with the most vegetation had a very low false crawl rate of 8.9%.

In this study, the false crawl rate is highest on Turtle Beach in 2005 and 2006, Mt. Irvine

Back Bay in 2007, and Grafton from 2008 to 2010. However in this it may be that the

sample size is not significantly high enough to draw any accurate conclusions from the

data. In 2007 the total number of hawksbill turtle nests was only eight and in 2008 only

nine.

As discussed previously false crawl rates can be a useful indication of the changing

aspects of a beach. In a nearby island, Barbados, it has been observed that hawksbill

turtles are deterred by highly-lit wide beaches when nesting, choosing instead to nest in

darker areas on narrower beaches (Knowles et al, 2009). It has also been recorded that

human presence and light pollution can cause an increase in the number of false crawls

(Witherington and Martin, 1996). By studying false crawl rates year by year, an overall

pattern may be found which could indicate whether a beach is suitable for nesting or

unsuitable due to lighting, development or human presence. In beginning to understand

this, a start can be made on trying to improve beach suitability for sea turtles and

prevent their nesting habitat from becoming unsuitable.

Although one of the aims of this project was to complete a population model with the

data, the nesting numbers of hawksbill turtles on Tobago in 2010 were too low for a

population model to be applied.

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Beach Profiling

From table 8 there does not seem to be a pattern in the slope preferences of hawksbill

turtles. Englishman’s Bay with 23% of nesting turtles has an overall slope of -9.5, with -

9.6 at the sea edge, whereas Mt. Irvine Back Bay, with 21% of nesting turtles has a much

lower slope at -4.7 overall and -6.2 at the sea edge. However in other studies it has been

recorded that hawksbills prefer a specific elevation, between 0.3 and 1.8m (Varela-

Acevedo et al, 2009). This was not included in this study and so it may be that slope is

not an important aspect but that elevation is. It can be seen from Table 8 that Mt. Irvine

Back Bay, Englishman’s Bay and Dead Bay are all key nesting beaches. These are all

relatively short, secluded beaches. Mt. Irvine Back Bay and Englishman’s Bay have an

abundance of vegetation found at the back of the beach. Dead Bay has slightly less

vegetation at some points, though there is still plenty to be found. It may be that these

beaches have shallow approaches to the beach and that offshore are rocks and coral to

be found. These have been shown to be preferred by the hawksbill turtle in a nesting

beach (Eckert et al, 1999). Future research could involve a study of the offshore profiles

of these beaches.

In a previous study by Horrocks and Scott (1991) they found that the beaches on the

west coast on the nearby island of Barbados tended to be steeper in slope on

emergence from the water, than east or south coast beaches. From this study the

results were similar in that the Caribbean coastline had an average gradient of -7.5 near

the sea edge as compared to -5.6 on the Atlantic coastline. Although slope seems to be

unrelated to turtle nesting percentage in this study it may be due to small sample size,

or it could be that slope is also an indicator of elevation, which has been shown to affect

hawksbill beach choice. It may be that hawksbills prefer to nest on the Caribbean

coastline, not only because it is more sheltered, but due to this the slope on emergence

is steeper and the elevation is more suitable.

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As stated previously regular profiling of Tobago’s nesting beaches may help to establish

important characteristics in sea turtle beach and nest site choice. By doing so perhaps in

the future, as a preliminary survey, beaches can be profiled in accordance to its

suitability as a turtle nesting beach, indicating whether there might perhaps be turtle

nesting occurring there. It could also indicate how recent development is affecting

coastal habitats and changing the profile of a beach.

Mapping

One of the aims of the project was to use GIS to create a visual representation of the

turtle nests. Unfortunately this was not possible however Google Earth and Bing maps

were used to present the data visually, if not as effectively as would have been

preferred. The GPS was not as accurate as desired and so the data points may be up to

five metres away from the actual nesting point. Despite this the maps are useful for a

visual examination of the data and to give an idea of relative location of turtle nests. For

instance on Grafton and Turtle Beach it can be seen that there are no nests found to the

north of the beach. This may be due to incoming wave direction, making nesting in this

area difficult.

Using GIS to visually present data is useful in that it can store data from many different

sources in a similar format. It can be used to analyse patterns and in the future could be

used to monitor changes over time. It cannot only be used for mapping nest locations

but also recording migration patterns over time, feeding sites and nesting beach

profiles. GIS not only creates maps presenting data but also stores data, linking it

geographically and creating relationships betweens features spatially and physically.

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Limitations and Recommendations

There are a number of limitations and aspects of the methodology that could be

improved.

There were many beaches on Tobago that could not be surveyed due to time and

money limitations and it was not possible to collect data for the whole turtle nesting

season. SOS Tobago collected data from the index beaches from the 1st March until 30th

September, however it was only possible to patrol non-index beaches from 16th June

until 5th August and the patrols could only be done weekly compared to nightly for index

beaches. Therefore deductions are limited since the data collected only represents a

small sample of the turtle nesting population on non-index beaches. The actual turtle

nesting numbers may be significantly higher than the data collected suggests.

If surveys of the non-index beaches spanned the whole nesting season instead of just

some of the season and if they occurred daily rather than weekly the results obtained

would be more accurate. However given the circumstances it was not viable to do so.

On some beaches such as Argyle and Kilgwyn there are no recorded instances of turtle

nesting. However this does not necessarily mean these beaches are not used for turtle

nesting, it simply means that during patrols no turtle nesting behaviour was observed. In

the case of Lambeau, no turtle nests were recorded during patrols. However towards

the end of the nesting season hatchling tracks were noted. It could be that on beaches

where there are high tides, turtle nesting behaviour is washed away regularly, giving the

impression on weekly checks that no turtle nesting behaviour occurs.

Due to the long life span of sea turtles and the length of time they take to reach

maturity this data is not useful in examining long term trends in the sea turtle

populations of Tobago.

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Recommendations and Future Research

Future research on the nesting behaviour of sea turtles on Tobago could include doing

more frequent surveys of non-index beaches. This could help to prevent the regular

poaching of threatened hawksbill turtles and lead to more conclusive data about what

beaches are important as hawksbill nesting sites and also to a better idea of hawksbill

nesting numbers for the island. By doing so, a more accurate population estimate can

be made for the island as a whole. It would be interesting to do a yearly population

estimate to be able to study population fluctuations in the future and to begin to

understand changes in the turtle nesting population of Tobago.

It would be interesting to study the beaches on which high tides may have washed away

turtle tracks, to see if turtles are actually nesting on these beaches. It could be that

turtles are nesting on these beaches, but high tides may still cause hatchlings to die

during development due to flooding. It would be interesting to survey these beaches

during the nesting season nightly to discover if turtles are nesting and to find out the

success rate of the nests if there is nesting occurring.

Due to time limitations it was only possible to profile the beaches once. However

beaches are highly dynamic and susceptible to change through erosion and accretion.

Visible change can occur over a period of years, months, days and even hours due to

wave and wind action, extreme weather and the flooding of rivers. Ideally beaches

would be profiled once a month to establish the beach dynamics and trends in accretion

and erosion, if not monthly then quarterly. Further information could be noted during

profiling that was not included in this study such as dominant vegetation type, sand

composition including grain size and compaction, high tide mark, low tide mark and

wave composition. These features would allow a more accurate characterisation of a

suitable nesting beach.

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It would be interesting to conduct interviews with locals to see if their reports of where

sea turtles are found match with what was observed in this study. Often fisherman and

coastal residents are very knowledgeable about whether turtles are found on local

beaches. It may be that turtles are nesting in significant numbers on other beaches not

surveyed.

It was not possible to use a population model in this study. This could be the next step in

assessing Tobago’s sea turtle nesting. By using data over the whole nesting season for

both leatherback and hawksbill turtles and including non-index beaches to ensure an

accurate numbers for hawksbill nesting, a more reliable estimate could be formed.

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Summary of Findings

Tobago is a significant nesting site for leatherback and hawksbill turtles. The

estimated number of leatherback nests on the 14 study beaches between 16th

June and 5th August on Tobago is 217. The estimated number of hawksbills for

the same time period over the 14 study beaches is 56.

False crawl rates for hawksbill turtles was 25%, and 16.7% for leatherbacks. This

is what was expected for hawksbills since they are smaller and more flighty.

False crawl rates seem to be increasing in recent years for leatherback turtles on

index beaches, perhaps due to an increase in human presence through patrolling

or perhaps due to an increase in tourism and development on the beach front.

Both leatherbacks and hawksbills prefer to nest on the Caribbean coastline as

opposed to the Atlantic coastline. This may be due to exposure levels on the

beach, wave energy, or beach profile, however further study is needed to

confirm this.

Tobago remains a significant island in relation to sea turtles. It’s coastal waters

provide a feeding ground for hawksbill and green turtles and its shores are used

as nesting sites for the leatherback, hawksbill and in previous years green turtle.

For these populations to remain stable long-term conservation is needed. This

has been attempted by SOS Tobago, however this is only one small non-

governmental organisation and it requires support from the government and

local people to expand its achievements and provide better protection for the

sea turtles of Tobago.

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Afterword

In the completion of my dissertation I have learned that even with the most careful

plans involved, field work is highly changeable and a certain amount of flexibility is

required when things do not go according to plan. Field work is unpredictable and even

the most carefully considered plans may have to change due to unforeseeable events. I

had not before considered the difficulties involved in the planning of research. There are

so many little things that need to be taken into account for the simplest of tasks.

I have released just how many limitations there are in research in terms of time,

resources and funding. I have also learned that by completing a research study in one

area, this opens up many other interesting areas and ideas to further explore.

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Acknowledgements

I would like to give a sincere thank you to Suzanne Livingstone and Roger Downie, for

their time and guidance throughout the development of this project and for their

continued support and encouragement.

I am indebted to Giancarlo Lalsingh, the program coordinator of SOS Tobago, without

whom the research could not have been carried out. He patiently drove me round the

island week after week allowing me to collect data. His experience and knowledge were

invaluable and his dedication to the conservation of sea turtles is admirable. I would

also like to thank all other staff members of SOS Tobago for giving me the opportunity

to go out to Tobago and work with sea turtles.

I am extremely grateful for the friendship of all the members of the Tobago Expedition

2010, and in particular Steven McGee-Callender, Katie Thompson and Joseph Crisp for

their help and assistance in beach profiling and day patrols. Their support was

invaluable. The advice and friendship of Rosanna Mooney and Grant Walker was much

appreciated when beach profiling and after returning to the UK.

I am thankful for the time my brothers Nicholas and Christopher Robb spent on helping

me with their IT skills and for the support of all my family.

I would like to express my gratitude to Mike Shand for his expertise in mapping and

geography and Kenny Roberts for providing an Abney Level for use in Tobago.

65

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Appendix Figure 3: Data sheet used in data collection on patrols.

All raw data is attached on a CD disk.