Category Archives: Cousin Island

Man and Mosquitoes on Cousin island

DEET confuses Mozzies

DEET confuses Mozzies

“Cousin  island is a MUST see – mozzies or not” said Varun Sharma the host of  Inside  Luxury  Travel, a TV program aired to millions around  the world. Mosquitoes on Cousin Island Special Reserve are particularly voracious this year. Swarms even follow people to the boats as they board to leave! It’s a huge problem because we cannot spray the air or water bodies with chemicals as that would destroy a large part of the ecosystem. Insect species as well as the endangered birds eating them would be devastated.

Visitors to Cousin are warned beforehand to carry personal mosquito repellent, But many arriving on this award-winning nature reserve still find that they are bitten. Basically, their repellent just does not work. As a result Nature Seychelles has had to distribute free repellent containing a substance called DEET. This is the best deterrent against the “pesky mozzies”.

When applied to the skin’s surface, DEET drives away mozzies looking for a free lunch (or dinner). But it can also keep the insects from ever getting close enough to land. Scientists have not really understood how the chemical works.  It was always thought that DEET was effective because it was repulsive or toxic to mosquitoes.

Now, a newly published paper in the prestigious journal Nature has shown that DEET is so successful because it works by targeting a mosquito’s sense of smell.

“The effects of DEET are not straightforward,” Maurizio Pellegrino, one of the authors  of the  paper, told the on line magazine Science News. “We think the insect doesn’t know exactly what it is smelling.” Pellegrino is a neuroscientist at the University of California, Berkeley.

Mosquitoes and other insects don’t have noses. They have receptors on their antennae that can pick up the chemical signature of a smell in the air. These receptors send information about the smell to the brain by way of nerve signals.

The study showed that these receptors are affected by DEET. The nerve cells sent different signals to the brain depending on whether DEET was detected alone or together with other scents.  The repellant also affected the insects’’ ability to detect other smells. As a result DEET somehow corrupts the nerve signal sent to the brain. That means DEET doesn’t necessarily drive mosquitoes away— it just confuses them so much that they fly away, says Science News.

“It’s as if you are hungry and you love hamburgers,” Pellegrino says. “If DEET is present, it doesn’t smell like hamburger anymore, even if a hamburger is right in front of you.”   So be warned – if you are visiting a mosquito infested area make sure your repellant contains DEET.

Nirmal Shah. This post first appeared in the Author’s column in the People.

Bird ringing on Cousin

Ringing is delicate work and ringers need training

Ringing is delicate work and ringers need training (Dieter Oschadleus)

From 18-23 September 2011 Dieter Oschadleus from SAFRING (South African Bird Ringing Unit) was on Cousin Island Special Reserve conducting training on ringing birds for the island’s wardens. Ringing and releasing birds is delicate work and ringers need skill and experience.The training was mostly on mist-netting of seabirds and land birds, a method used in bird ringing. A total of 478 birds were caught and ringed including recaptures. Riaz Aumeeruddy, Nature Seychelles Science and Conservation Coordinator was at the training and we took the opportunity to ask him a few questions. Following are his answers.

Why do we ring birds?

There are different reasons for ringing birds. One is to be able to identify birds individually in a population, usually using a combination of different coloured rings. This is what is done on Cousin with the endemic Seychelles magpie robin and the Seychelles warbler, where each bird is colour ringed. Usually most ringing programs involve only putting a metal ring with a unique ID on one of the legs of a bird. This will allow, if the bird is recaptured, to get information on its movement (on the island itself or inter-island), on its longevity (eg. a Seychelles fody ringed in 2002 on Cousin was recaptured during the training course, showing the the bird lives at least 9 years, information on the longevity of the Seychelles fody has never been published before) and social associations. Bird ringing can help answer a number of questions relating to causes and factors contributing to population movement, dynamics and behaviour.

Which types of birds do we ring?

On Cousin, we systematically ring two species of land-birds: the magpie robins which are ringed by the Cousin staff, and the Seychelles warblers that are ringed by the scientists from the warbler research group. Ideally all the birds of these two species are ringed, to know the exact population, and the territories in which they live on the island. Other landbirds are ringed for specific projects; the Seychelles fody was ringed on Cousin by a student who was doing her PhD on that species. Some species of seabirds are also ringed on Cousin, for example the White-tailed tropicbird and the Lesser Noddy are ringed during study of their breeding success (parents and chicks are ringed when they are on the nest).

A ringed Seychelles warbler (L, Cas Eikenaar) and magpie robin (R, Glenn Jackaway)

A ringed Seychelles warbler (L, Cas Eikenaar) and magpie robin (R, Glenn Jackaway)

What do the different colors mean?

Colour rings are used in a unique combination (2-3 rings) which helps identify each bird. For the  magpie robin, 1 colour ring is attached to the right leg to identify the island (eg. Cousin uses a Red ring) so if a bird flies from one island to the other, we can know from which island it is from, and 2 colour rings are attached to the left leg to identify the bird. With this system, the whole genealogy of a bird can be determined. For the warblers, 1 colour ring is used to identify the year the bird is ringed, and 2 colour rings for identifying the bird.

What was the outcome of the exercise

Four wardens, the science officer and myself attended the training course. All the participants received certificates. We need to thank Dieter Oschadleus from SAFRING for conducting the training, and the warbler team (Martijn Hammers, David Wright and Sjouke Ann Kingma) for their assistance during the course.

The Lesser noddy was the most ringed species

The Lesser noddy was the most ringed species (Dieter Oschadleus)

Thanks Riaz.

Dieter has also reported on this ringing exercise here and has provided a table of the species and numbers ringed.

Long live the Giant Tortoise!

Giant tortoise of Cousin beach

Giant Tortoise on Cousin beach © Martin Harvey

The News that the oldest living animal in the world, thought to be a giant tortoise who lives on the island of St Helena in the South Atlantic Ocean, originated from the Seychelles excited many here last week.

The Telegraph reported that Jonathan is the sole survivor of three tortoises that arrived on St Helena Island in 1882 from the Seychelles. He was already mature when he arrived and was at least 50 years old, therefore his minimum age is estimated to be 178 years old.

Another giant tortoise, an Aldabra Giant Tortoise that died in 2006 in the Alipore Zoological Gardens in Kolkata, India, and whose approximate age was later determined through carbon dating to be 255, was the previous oldest living tortoise  and was also from Seychelles. Adwaita, the pet of a general of the British East India Company,  was captured by British seafarers from the Seychelles and taken to India.

People have always been fascinated by giant tortoises. Even today, their gentle ET-like demeanour, slow lumber and the fact that they will submit to a petting without too much fuss makes them a popular attraction on islands where they have been introduced like Cousin Island Special Reserve. Aldabra Giant Tortoises roam freely around Cousin and the larger ones can usually be found on the beach in the early morning. George, Cousin’s oldest tortoise,  and Kasban, who hangs out near the visitor shelter, are among the favourites and are possibly some of the most photographed tortoises in the world!

The Cousin population was introduced in the past. When the island was sold to ICBP (now BirdLife International) there were several tortoises and they were included in the sale price of the island. They were originally kept impounded in a stone-walled tortoise enclosure of about 2 acres in size until they were released in 1980. In 2000, 6 females were purchased and brought to the Reserve in an adventure filled journey. Now they live free, enjoying a diverse vegetarian diet that includes noni fruits (fruits of the Indian mulberry tree, bwa torti). Perhaps that’s why they live for so long and seem to be full of energy.

Aldabra Giant Tortoises are endemic to the Seychelles. An estimated one hundred thousand of them live in the wild of the Aldabra Atoll, and several hundreds have been introduced to various islands of Seychelles including Curieuse, Fregate and Cousin. They are also widely kept in captivity. But tortoises were nearly wiped out. As an important food source for seafarers visiting Indian Ocean islands in the 17th to 19th centuries, they were hunted, captured and stored for meat on ships. This exploitation, the destruction of habitat and the introduction of predators decimated the populations, with the exception of those on the Aldabra Atoll.

Giant tortoises are listed as ‘Vulnerable’ in the IUCN (World Conservation Union) list of endangered species and their international trade is restricted by the Convention on International Trade in Endangered Species (CITES).


How many tortoises hang out on Cousin Island?

Tourists meet the island's Giant Tortoises (James Luxton)

Tourists meet the island's Giant Tortoises (James Luxton)

Most visitors to cousin would be familiar with the Giant Aldabra tortoises that lumber out near the visitor shelter to meet the tourists when they arrive. And more are to be seen as one walks through the forest and in the wetland area, a nice cool place to hang out. But how many more tortoise are on the island?

This is the question that two volunteers Sarah and Dale  recently helped Nature Seychelles to answer. Sarah and Dale helped to tag the Giant Tortoises on Cousin Island Special Reserve to monitor the population with a scientific approach. They  worked tirelessly to find all the tortoises, tag them for a population census, answer a few burning questions and train the wardens so that they can continue with future tagging.

tortoises of all sizes were tagged

35 tortoises were tagged

Sarah and Dale found and tagged 32 tortoises and 3 more were tagged by wardens after their 5 day stay.  We now know there are 35 tortoises.  However it is likely they did not find all the smaller sized tortoises and Sarah and Dale are thus estimating that between 40 and 45 tortoises reside on the island.  Over the course of coming months (and years) wardens will continue to tag tortoises and the additional data will be added to the database to ensure increasing accuracy of the population estimation and up to date records.

From the Census we have also learnt that the majority, 69% of tagged tortoises on Cousin Island, are greater than 90 cm long with the next largest grouping at 26% in the 46-90 cm long category.  Only one (3%) in each of the: 15-45 cm; and less than 15 cm long categories were found.

all sizes

in different sizes

The tortoises roam freely and likely enjoy a fairly diverse diet and fresh water. The wardens, who inform tourists about the island and the conservation work, had been reporting that there were 28 tortoises but thanks to this project they can update that information and raise awareness about the growing population of tortoises on Cousin Island.

This post is extracted from an article for Zwazo magazine by Sarah Bunce

Conservation hurts!

Lately,  visitors to Cousin Island Special Reserve have remarked about the increase in mosquitoes.  Island management has noticed a swell in numbers during certain, usually short, periods in the past few years. Mosquito densities vary between seasons, and in drier seasons they are few and go virtually unnoticed. Recent heavy rainfall have contributed to the current numbers.

“After heavy rainfall they seem unavoidable,” explains Ian, Cousin’s manager. “We don’t use pesticides because this is a Nature Reserve, so we can’t control them in this manner. We however advise visitors to carry repellent, particularly that which contains a certain percentage of DEET, which is very effective. In addition we provide repellent to visitors upon arrival.”

“It is variable, some years we do not have mosquitoes at all,” echoes Riaz Aumeeruddy, Nature Seychelles’ Science Coordinator. “We have noticed a reduction as the season has began to change and we have a stronger wind blowing.”

In reality, the mosquitoes haven’t stopped visitors enjoying the 90 minutes tour of the island during this time. The wardens explain to visitors that the mosquitoes do not carry Malaria, can be controlled with repellent and when bitten, after the initial itch most people recover quickly after application of ointment. Indeed the majority of reviews and visitors’ comments recorded have one thing they agreed on completely: a visit to the island is not to be missed.

“Cousin Island is a MUST see… mozzies or not …” says Varun Sharma of the hit series Inside Luxury Travel, who began his blog post about his visit there by declaring, “I hate mosquitoes!” before proceeding to describe Cousin as filled with wonderful biodiversity.

The scientists, researchers and volunteers who arrive during this season and must contend with the mosquitoes also agree that one gets used to them. These comments are rewarding as Cousin Island and the vital conservation work done there depend largely on eco-tourism revenues.

Science officer Mary (R) and volunteer covered in mosquitoes as they tag tortoises

Science officer Mary (R) and volunteer covered in mosquitoes as they tag tortoises

Mosquitoes are common in all parts of the world. There are over 3000 species. A majority of species do not bite humans (only a few hundred do). Some are pollinators and food for animals including fish. But in the tropics where they are responsible for the spread of Malaria, Rift Valley fever, Chikungunya and West Nile viruses, sentiments way heavily towards their complete eradication, although means and consensus on the impact this would have on the natural order of things have not been found.

Zone Australe discovers Cousin

The Reunion TV programme Zone Australe produced by Serge Marizy last year journeyed through Seychelles discovering its magical islands that included the Cousin Island Special Reserve. The programme was aired in Reunion earlier this year and can be seen here in its entirety. Its about 32 minutes and is in French (Reunion Island is a department of France).

With the permission of Serge Marizy, we have extracted the part on Cousin. See Eric, J’elle and David explain its attractions (also in French):

embedded by Embedded Video

YouTube DirektCousin Island Courtesy Zone Australe

Photographing the elusive Syer

Well hello Mr. Owl

Well hello Owl

One of the things I like about working in conservation is taking pictures of wildlife. As challenging as it can be, it is an absolute delight to see the results when a good picture is taken. In Seychelles and on Cousin Island Special Reserve especially there are great opportunities for taking bird pictures. The birds make it easy on the Reserve because they are so unafraid of people and do not move away when approached. Cousin is predator free, so the birds have hardly anything to fear. We have in our database now hundreds of pictures taken by staff, volunteers and visitors. We have shared some of them and I love it when I get a good reaction to a picture.

But although its relatively easy to get pictures of the bird life, sometimes its near impossible to get pictures of some birds. The Seychelles Scops Owl (Syer, Otus insularis) comes to mind. This is a nocturnal bird restricted to forests at mid and high altitudes of Mahe, the main island of Seychelles. The population is fewer than 360 birds so it is still on the endangered list. It is a rarely seen bird and in fact it was not until 1999 that a nest was found. But a few people know its whereabouts and can help in locating it. Camille Hoareau is one of these people.

Last year we had French photographers Herve Chelle and Jean Phillipe Vantighem helping us add to our photographic database. JP and Herve work for the NGO Le Sternes, which provides photography expertise to protected areas on a voluntary basis. During their time on Mahe we asked them to help us get pictures of the Scops owl and the Seychelles sheath-tailed bat another elusive species. We called on Camille who lives up in the hills for his help. Using the Scops Owl call,  a double frog-like croak that resembles a saw – thus its Creole name meaning sawyer, Camille was able to attract a pair for Herve to take pictures of at dusk (see above). In between, we stood there awed for over an hour just watching them, feeling lucky.

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.


From Boise with love: American students get a taste of the islands

On a tour of Cousin

On a tour of Cousin

A group of graduate and undergraduate biology students from Boise University, Idaho were recently in the Seychelles on a course to learn about the uniqueness of our islands biodiversity. They were accompanied by Profs. Marc Bechard and Massimo Pandolfi of Boise and Urbino University respectively. Prof. Pandolfi, who has a long association with Nature Seychelles, has organised similar courses in the past four years.

The course that began on Monday 10 January 2011 and lasted a week, included field activities that saw the students visit Seychelles conservation hotspots of Cousin Island Special Reserve, Curieuse Island Marine Park, Vallee de Mai, La Digue and beaches around Praslin. The visits gave students the opportunity to observe plants and animals and to collect data for assigned field projects.

The training held at our Centre on Praslin brings attention to Seychelles and is also an avenue for future collaboration. Indeed past graduates of the course have returned to the islands to visit as students – at Masters and PHD level, and have also contributed as volunteers on sites like Cousin.

Lectures on the flora and fauna of the Seychelles, its geology, human settlement history, the extinction of endemic species, and current conservation efforts to preserve the biological diversity of the Seychelles were given.

Although heavy rainfall interrupted some of the planned activities, the students were happy they made the trip. In between learning, the students found time to take in local culture.