Category Archives: Turtles

Special Turtle lays eggs – with a little help from her friends

An exhausting but successful Hawksbill turtle nesting season on Cousin Island Special Reserve was topped by the appearance of an extraordinary turtle nicknamed “Stumpy” by island residents.

The Hawksbill turtle arrived on the island devoid of her right rear flipper and part of her carapace. But in spite of her missing flipper she made several attempts at nesting, finally succeeding with the help of the turtle team to lay not one, but two nests!

Turtles use their flippers to swim in the ocean where they spend most of their time. They also use them on land.  With the front ones they crawl out of the sea and drag themselves across the beach to nesting sites, and once there, digging what is called a body pit. With the hind flippers, they excavate the pits within which eggs are laid.

She was missing her right rear flipper and part of her carapace

She was missing her right rear flipper and part of her carapace

“Her right rear flipper was missing and a chunk was taken out of her carapace, but this did not stop her natural instinct to lay,” says Kat one of  Cousin’s Turtle Team Volunteers.

“Throughout the season we encountered tagged turtles, on average, 3 times. However she attempted to lay 10 times,” she continues, describing the persistence of the turtle.

 “At first we thought she would not be able to complete the laying process because although the damaged flipper went through the motion of digging an egg chamber, no sand was shifted. But with help from us, scooping sand out of the way, she managed to dig an egg chamber and laid her two nests.”

But with help she laid two nests

Stumpy’s flipper and the carapace is suspected to have been chomped off by a shark.

This is not the first time that the turtle has been spotted on the island. Female turtles instinctively return to the island where they were born to nest as adults and two years ago she was spotted.

“I remember helping Stumpy to nest,” says Alec another volunteer who was on the island at the time, “Sand to the face but worth it!”

Despite a late start, this season Cousin Island experienced the highest number of nesting female hawksbill turtles in recent years.

The high numbers are obviously good news for the turtle population nesting on Cousin Island, which is one of the world’s longest running hawksbill monitoring programmes, but meant a very exhausting few months for the volunteers and wardens of Cousin Island.

“But it has been incredibly interesting for me seeing the whole lifecycle happen on Cousin Island,” says Kat. “From Sighting turtles mating in the waters around Cousin and watching females emerge to lay eggs on the island to hatchlings pouring out of their nest in their hundreds and then snorkelling and seeing juvenile turtles feeding around the island.”

 “It really brings home how important this small island in the Seychelles is for ensuring the continuation of this ancient species. I can only hope in the future there are more and more bumper years like this and the same turtles and their offspring keep returning,” she says.

Seychelles – a great place to be a turtle!

while she lays, data are collected (Herve Chelle)

Turtle program on Cousin started in 1972 (Herve Chelle)

Last week I was on Cousin Island Special Reserve, with a group of visitors on a guided tour of the island. On the beach we watched as a hawksbill turtle made its short journey back to the sea from laying her eggs. Laborious on land, but effortless in the sea, the hawksbill turtle lays more than 100 eggs into a small pit dug in the sand.

The Seychelles in general and Cousin Island in particular is a great place to be a turtle. Every year around this time, hundreds of female hawksbill turtles will arrive on one of our beaches to nest. The archipelago provides key nesting and feeding areas for the critically endangered hawksbill and is home to the largest remaining population in the Western Indian Ocean. This population, sea turtle experts have said recently, is among the twelve healthiest sea turtle populations globally.

A report produced by IUCN (International Union for Conservation of Nature) Marine Turtle Specialist Group (MTSG) has revealed the most threatened and most healthiest of all sea turtles (there are 7 species) populations globally. It is the first comprehensive status assessment of all sea turtles. See this story here.

It shows that the hawksbill turtles populations in the Southwestern Indian Ocean (Seychelles, British and French Overseas Territories) and in Southeast Indian Ocean and Southwest Pacific Ocean (Australia) are the healthiest. But Hawksbill are threatened in the East Pacific Ocean, East Atlantic Ocean, Northeastern Indian Ocean, and West Pacific Ocean.

The report says that the most significant threats to sea turtles are fisheries bycatch, accidental catches of sea turtles by fishermen targeting other species, and the direct harvest of turtles or their eggs for food or turtle shell for commercial use. The healthiest populations are large and currently facing relatively low threats.

Hawksbill turtles were heavily exploited for many years in Seychelles, mainly for their shell. In 1994 a law that granted them complete protection was passed and harvesting was completely banned, although occasional poaching still occurs.

Turtle conservation is carried out on many islands. One of conservation’s success stories for the hawksbill turtle has been registered on Cousin Island, where a long-term monitoring programme started in 1972 is firmly established.

Turtles, Tortoises and Torti: a voluntary week on Cousin Island

The following account of Sarah Bunce’s voluntary time on Cousin Island during the turtle season appeared in Zwazo, Issue 22, which is available for free download.

I’ve just returned from a wonderful week on Cousin Island where the boat ride up onto the beach is just beginning of the rush of things to do and see as a volunteer.

As the Hawksbill sea turtle egg laying season is just peaking my friend and I were able to lend some hands to the sea turtle monitoring programme.  Cousin Island Special reserve has been collecting data about sea turtles since 1972 so Gilles-David Derand, the Nature Seychelles Science Coordinator from Mahé, showed us the ropes of this well established programme.

We had a bit of time to settle into our digs and meet the 3 students from the Seychelles Maritime School who are on Cousin for a month of work experience before their graduation; plus a volunteer from the Royal Society for the Protection of Birds, UK.  It was a fun group of young women living away from home for the first time and generally enjoying one another’s company.

Then it was off to find turtles on our first patrol.  As hoped, the turtles were out and about.  I had the great pleasure of watching the process from body pitting to returning to the sea.  During body pitting the turtle settled herself into the sand, under some vegetation for shade, by using her front flippers and body to create an impression of her body while clearing away the surface leaf litter.  Once she seemed comfortable, she started to dig the egg chamber.  This fascinating process involves the use of her back flippers in a highly agile and manipulative way.  She is able to create a long scoop with her flipper to dig sand from as deep as 60cm.  It looks like she scoops the sand up with one flipper dumps it and then pushes it away with the other flipper.  Alternating flippers she achieved her goal.  Between sessions of flying sand there were lovely pauses when she seemed to catch her breath and worked up her resources to recommence the dig.

flying sand as this turtle digs her chamber (Herve Chelle)

flying sand as this turtle digs her chamber (Herve Chelle)

Then, the laying began, peering down into the depths; I could see the light yellow ping pong ball size eggs dropping into the chamber.  Again there were little pauses in the process, when she would raise her head a bit and seem to take a deep breath before more eggs would drop.  After about 45 minutes she was finished with the hard part.  Now she pushed the sand over the eggs and proceeded to gently pat the mound under which her babies would incubate for the next 65 days, again with her rear flippers.  Finally, she camouflaged the mound and nest to prevent the ghost crabs or other predators from digging up the eggs for supper.  Camouflaging seemed to involve a lot of flying sand and generally stirring up the surface near the nest to spread vegetation.  She created a clear crescent with her front flippers maybe to infer the nest was located a bit further away. Read More »

The adventure begins…

the hatchlings head to sea

the hatchlings head to sea (Alison Giacomelli)

look at this guy move

look at this baby move ! (Alison Giacomelli)

After a hard days work our 2 volunteers Carrie and Alison saw these hawksbill hatchlings making their way down to the sea just after 6pm. They had probably been waiting for the sun to go down before emerging when it was a bit cooler. They a ll made their way down to the sea in a big group and with the help of the volunteers and Science Officer Mary they managed to avoid the ghost crabs who were waiting on the beach in search of a tasty meal. The hatchlings swim out to sea where they are carried off by ocean currents. The first few years of their life are known as ‘The Lost Years’ as we don’t know exactly where they go, although it is believed that they spend some time drifting on rafts of algae, feeding and growing. When they are a bit older they start coming back to inshore areas to feed. However it’s not until they reach 35-40 years that they begin breeding and we’ll see the females coming back to the beaches of Cousin. Amazingly, females find their way back to the same beach where they hatched to lay their eggs.

Jakawan

The turtles are back

It’s hawksbill turtle nesting season once again here on Cousin…

Female turtle coming in to nest. (Peter Chadwick)

Female turtle coming in to nest. (Peter Chadwick)

And so its tagging…

Tags are checked or applied on flippers for monitoring. (Peter Chadwick)

Tags are checked or applied on flippers for monitoring. (Peter Chadwick)

…and measuring time.

data such as size of turtle is collected (Peter Chadwick)

data such as size of turtle is collected (Peter Chadwick)

Cousin has one of the longest hawksbill turtle monitoring programme on the western Indian Ocean.  Tags applied to the turtles’ front flippers are used to identify individuals and to provide an estimate of the size of the nesting population. Other information such as the size of the turtle and tracks are also noted and the location of any nests are marked and recorded. Turtle nesting season ends in February.

Conservation success: Eight-fold increase of turtle nesting on Cousin Island

Cousin Island Special Reserve has recorded a phenomenal eight-fold increase in abundance of nesting hawksbill turtles since the early 1970s based on new analysis of data, a scientific paper published in the Endangered Species Research journal has revealed. The increase is directly attributed to the ongoing turtle conservation program on Cousin started in 1972.

“These findings are a validation of the important work carried out on Cousin.” Says Nirmal Shah Chief Executive of Nature Seychelles – BirdLife’s partner in the Seychelles, which manages the island. “It is long awaited proof that conservation works even for long lived and critically endangered species like marine turtles.”

Turtle nesting on Cousin Island © Nature Seychelles

Turtle nesting on Cousin Island © Nature Seychelles

The evidence shows that Cousin Island, an Important Bird Area (IBA) known for saving birds like the Seychelles warbler from the brink of extinction,  is also a sanctuary for other endangered species. “At 29 ha, it is one of the smaller islands within the granitic Seychelles yet one of the most important nesting grounds within this region.” The paper says.

Data collection © Nature Seychelles

Data collection © Nature Seychelles

Turtle populations are notoriously difficult to census, relying upon long-term monitoring of females at their nesting beaches. This makes the monitoring on Cousin a mean feat.

Turtle monitoring commences each season when wardens observe the first evidence of a turtle emerging onto the beach to lay her nest. This generally occurs around late August, and turtles continue to emerge until late February or early March. Beaches are periodically patrolled. A complete patrol involves a full circuit of each of the 4 beaches on the island and varies in duration from 30 minutes to 3 hours, depending on the number of turtles and tracks encountered. Females emerging on Cousin are individually tagged, and nesting data collected from nesting attempts  observed through tracks  and actual turtle sightings.

“Survey effort varied over the years for a variety of reasons, but the underlying trends over time are considered robust.” The authors say.

Tag returns also show inter-island nesting occurs between Cousin and other islands within the Seychelles.

The archipelago provides key nesting and feeding areas for the hawksbill. Seychelles accounts for breeding populations estimated to be in the thousands and is home to the largest remaining populations of hawksbill within the western Indian Ocean.

Hawskbill turtles have been protected by law since 1994 when a total legal ban on turtle harvest was implemented. But populations had already declined due to widespread harvesting of nesting females during the 30 years prior to that, with the exception of Cousin. Some poaching still occurs and there have been several arrests and legal cases.

A worldwide trade in turtle shells had also significantly depleted this species globally. In 1996 a total international ban on trade in this species was instituted. Problems of by-catch and habitat destruction still remain in some countries. In the same year the World Conservation Union listed hawksbill turtles as ‘Critically Endangered’.

Paper: Allen et al. 2010. Hawksbill turtle monitoring in Cousin Island Special Reserve, Seychelles: an eight-fold increase in annual nesting numbers. Endang Species Res 11: , 2010 available for download at our website

Cousin Island Special Reserve has recorded a phenomenal eight-fold increase in abundance of nesting hawksbill turtles since the early 1970s based on new analysis of data, a scientific paper published in the Endangered Species Research journal has revealed. The increase is directly attributed to the ongoing turtle conservation program on Cousin started in 1972.

“These findings are a validation of the important work carried out on Cousin.” Says Nirmal Shah Chief Executive of Nature Seychelles – BirdLife’s partner in the Seychelles, which manages the island. “It is long awaited proof that conservation works even for long lived and critically endangered species like marine turtles.”

Baby hawksbills begin to come out

Happy New Year

We have good news here. The waiting period – approximately 60 days – is over and hatching of Hawksbill turtle eggs laid on the Cousin beach has began. Mary and Eric have had a busy time with turtle work. The work continues with the hatching. As reported earlier, apart from the regular monitoring program based on beach patrols carried out around the island to intercept and collect data on as many turtles as possible, Nature Seychelles – with technical assistance from Kelonia Marine Turtle Observatory in Reunion – this season introduced the use of data loggers to measure temperature in selected nests. Temperature inside the turtle nests is known to determine the sex ratio of hatchlings. Warmer temperatures produce more females and cooler temperatures give more males. This is an important area of study, as with rising global temperatures, it is important to understand the potential impacts of climate change on this critically endangered and thermally sensitive species.

When hatching occurs in the nests with data loggers (30 in total) Mary and Eric pick up and measure the weight and length of 30 of the hatchlings, as well as categorizing nest content to determine hatchling success.

weighing.jpg

measured.jpg

They are then put in basket such as the one below with a shadow to avoid dehydration.

mary-eric-hatchlings.jpg

When the sample hatchlings have been measured  and weighed, they are released and head out to sea. The release is controlled to avoid the high level of predation by ghost crabs.

released1.jpg

hatchlings-head-to-sea.jpg

It is impossible to tell the sex ratio of the hatchlings when they are this small. But from the data collected from the data loggers it is possible to determine the approximate sex ratio using existing and new temperature data. We will give you more information on how this pilot study evolves.

More on turtle work

Turtle laying her eggs

Hawksbill turtles go into some sort of trance when laying their eggs and mademoiselle here shows us how that looks like.

Eggs weighed and measured

While she is in this low state of awareness, her eggs are quickly counted and weighed.This is done by two people as it has to be done very quickly before she completes laying and starts covering the nest with sand. If she does complete her egg laying before the weighing and measuring is complete the eggs are quickly put back anyway.

data logger

This is the tail end of the data logger (and turtle :)) which is also currently being placed in the nest. Nature Seychelles is piloting this experiment with data loggers – with technical assistance from Kelonia – to gauge nest temperature. Data loggers record temperatures of nests throughout incubation. Sex determination in sea turtles is dependent on temperature, with a pivotal temperature in which equal numbers of males and females are produced. Temperatures above this pivotal number produce females and those below produce males. So data loggers help with sex ratio determination. The temperatures can also be used as indicators of the potential impact of  global warming on hawksbill turtles.

Photo ID anyone?

No two individuals, even identical twins, have identical sets of fingerprints. For this reason fingerprints offer a reliable means of identification. They have played a huge role in the area of forensics providing accurate identification of criminals.

As it turns out, marks and patterns on certain marine animals are akin to human fingerprints and are unique to each individual. These marks are being put to good use, not to catch the criminals of sea world, but as a means of identification to help in conservation.

On Thursday 12 November, the Marine Conservation Society Seychelles, in collaboration with the Kelonia Marine Turtle Observatory in Reunion and Ministry of Environment organised a talk on how this form of identification is being utilsed for whale sharks and turtles. The talk, “using images to conserve endangered marine life” was delivered by David Rowat, MCSS, who is working with whale sharks in Seychelles  and Claire Jean from Kelonia working with turtles. As in humans where fingerprints develop at the embryonic stage and do not change, all indications in these marine animals are that marks are usually permanent with little change occurring over time.

According to Claire, Kelonia uses underwater photos of marine turtles head profiles for indetification. Their methodology consists of analyzing scale numbers and shape of both right and left profiles. Photos of these profiles are taken for each turtle. A database has been created to keep these photos. The matching of the new data with those in the database allows one to determine whether or not each marine turtle has been seen previously. Thanks to the participation of scuba divers and marine photographers, photos can be collected throughout the year in various sites.

Claire says photo ID can be used as an alternative or complimentary monitoring method. But she noted that current monitoring methods that use capture-mark-recapture techniques, require physical application of tags. Photo ID on the other hand is non-intrusive, less costly and less stressful. It is particularly useful in places where marine turtles cannot be caught and tagged and helps in situations where tags are lost. It also targets all turtles unlike the capture method, which mostly targets females and juveniles. It can be used in all habitats either at sea or one beaches. What it cannot be used for is measuring other parameters such as growth.

For whale sharks, researchers use photographs of the skin patterning behind the gills of each shark and any scars to distinguish between individual animals. Cutting-edge software supports rapid identification using pattern recognition and photo management tools. See whaleshark.org  for more information. David Rowat said that using this method between 2001-2009, 447 individual sharks have been identified in Seychelles. Fifty percent were re-sightings.

Picture via whalesharks.org

Both these projects rely on the contribution of pictures from people, and pictures come via tourists, scuba divers and others, allowing for public participation. They are asked to take good high resolution photos without obstruction, such as sand on turtles.  Identification however is done by trained people.The talk ended with an offer from Kelonia to conduct training for organizations involved in turtle monitoring in Seychelles.

Turtle nesting foray begins

It is that time of the year again and hawksbill turtles are making their annual pilgrimage to our shores to nest. The hawksbill breeds throughout Seychelles, peaking between mid-October and mid-January.  On Cousin Island, Conservation Officer Eric Blais reported an early appearance on August 8. Appearances are starting to pick up now and more turtles will arrive in November, December and January.

As numbers peak, so will monitoring. On a short visit to Cousin yesterday (9 Nov 2009), I took part in an afternoon monitoring exercise with Eric, David (Science Coordinator for Nature Seychelles), Mary (a volunteer helping with the turtle work) and Claire (from Kelonia) to see just what this means.

Cousin Island has one of the longest running monitoring programmes – started in 1972 – forming a core part of the wardens and volunteers work programs. Appearance dates and locations have to be recorded, with nesting beaches being patrolled several times a day. Metal tags with unique identification code, attached to the front flippers of each nesting turtle encountered help identify individual females returning to the beach each season.

Turtle emergences are recorded under four categories of behaviour: 1) “LAID” during which eggs were laid after digging one or more nests; 2) “Did Not Lay (DNL)” during which one or more nests were dug but no eggs laid; 3) “Half Moon (HM)”emergences during which digging did not occur although no disturbance factors were apparent; and 4) “Emergence Stopped by Obstacle (ESBO)” during which no digging occurred because the female was discouraged by obstacles on the beach.

After a short walk, we came across a female who had just begun to dig her pit. As I took covert pictures of her, my colleagues went about taking their data and doing their tagging. To my utter surprise Mary put her hand into the pit and with a counter in the other, began to tally the eggs as they came out.

Mary takes count

A female turtle crawls out of the sea and using her front flippers drags herself up to the beach to a suitable nest site. There, she digs a pit with her front flippers and then excavates a vertical egg chamber with her hind flippers in which she lays her eggs. Eggs can be as many as 250. Mary counted 210 eggs for this one! Afterwards, the turtle used her hind legs to cover up the nest with sand and returned to sea.

It will take close to sixty days for the eggs to hatch and two or more days for the baby turtles to get to the surface. The babies will emerge as a group and – usually at or after dusk – head towards the sea attracted by the reflection of the moon on the water. But they face a number of challenges. Once hatched, babies are a favorite food for ghost crabs, birds and fish. Baby turtles could also be affected by beach lighting, which can cause them to head inland rather than out to sea. On Cousin, lights are of low wattage and screened from all nesting beaches.

As I left Cousin, I reflected on the work ahead for these hardworking people. Things will certainly get very busy soon. But thankfully, the collection of data will be increasingly efficient due to new technology and data analysis techniques that are being introduced.