Thursday 2 August 2018

The Seychelles Magpie Robin

Photo: A Seychelles Magpie Robin (CTagg)

The Seychelles magpie robin (Copsychus sechellarum) at one stage was facing extinction. With numbers as low as twelve, it looked like this species would be consigned to the ages as another extinction brought about by habitat destruction the accidental introduction of rats (stowaways on shipping vessels). Fortunately this has not been the case at all and they have been a truly remarkable success story of conservation proving that it is not too late to take positive action and save a species.


Photo:SMR feeding on Banyan fruit (CTagg)
Denis Island has the privilege of being a part of their recovery. The magpies are believed to have inhabited most of the Granitic islands of the Seychelles however with the development of these islands and the introduction of rats by accident and cats (to control the rats), they quickly went extinct on all but one island (Fregate island). As part of the recovery efforts, the magpies were translocated to other islands that provided the right habitat for the and crucially, were rat and cat free. Translocation efforts not only increase the overall area the birds can be found in thus allowing a larger population of this highly territorial species, they provide security that should a population fail due to disease, habitat destruction or introduced threats, populations of wild birds still exist.

Denis Island was one such destination and, in 2008, 20 magpie robins were translocated here. Since then, the birds have been monitored by conservation staff on the island to ensure the population is stable/ growing and the birds are showing no signs of disease or abnormal behaviour. It is was observed that the invasive myna bird on Denis was having a detrimental effect on nesting success as this problematic species is a nest raider eating both eggs and chicks. This species was eradicated in 2015 and it is with great pleasure to say that since the initial 20 birds first released, the 2016 census showed magpie numbers on Denis were up to 78!

Photo: The Seychelles magpie robin has a varied diet and is capable of hunting and feeding on the Seychelles skinks; Trachylepis seychellensis (CTagg)
Success stories like this are only possible thanks to constant monitoring of populations of wildlife especially species at risk and then the appropriate steps taken to ensure success. Even after the huge challenges of moving a species, constant monitoring still needs to be done to look for any potential problems on the horizon which can be prevented before having a chance to take hold.
By visiting Denis or the other islands with magpie populations, you are helping contribute to the protection of such a fascinating species and we hope you are fortunate to see these charismatic birds whilst you are here.
Photo: The feathers of a Seychelles magpie robin are very glossy so in sunlight shimmer iridescently (CTagg)

Fun fact: The Creole name for this species is pisantez means ‘singing pie’. Pie after the birds black and white plumage, and singing because of its melodic voice.

Wednesday 30 May 2018

The green turtle on Denis island

The Green Turtle is part of an order of reptiles that have been on this Earth for 220 million years. They survived the extinction that wiped out the dinosaurs, several ice ages and now as a result of direct and indirect human action they could disappear! The green turtle (Chelonia mydas) for years was hunted as a source of meat. This, coupled with the pollution of the world’s oceans has led to drastic declines in numbers of turtles. An estimated 170,000-180,000 green turtles remain. This may seem a large figure however compared to seven billion humans, some perspective can be seen! Worldwide awareness is now the highest it has ever been and efforts are being made at small and international levels to conserve the turtle species.

The Seychelles is perhaps the best example in the Indian Ocean of turtle conservation. Several NGOs and experienced researchers are working with the government and local community to bring about change to save these ancient species. As a result of the continued efforts happening and strict anti-poaching laws in the Seychelles, the turtles that return each year are afforded protection and it is hoped this will lead to population increase. 
Photo: Green turtle track (CTagg) 

Here on Denis Island, the green turtle nesting season has begun. Emergences at night have been seen over the last few weeks with 10 emergences recorded on the 21st of May this year!  An emergence is when the female returns to the beach she most likely hatched from decades before to lay her own eggs. This is the only time a healthy turtle will ever return to land. The green turtles emerge under the cover of darkness usual at high tide and drag themselves up the beach to lay anywhere between 75-200 eggs before returning back to the ocean.

Denis Island is not just used as a nesting site for this endangered species, but the waters around the island are a crucial foraging ground for immature turtles. The seagrass meadows are perfect for the young turtles offering both food for their development and safety for the large predators found in deeper water. In return the turtle grazing opens up the meadows allowing for a richer invertebrate and fish community, making them a crucial component of the ecosystem! Turtles on Denis can be frequently seen from the shore coming up for air and swimming in the shallows grazing on the seagrass. 
Photo: Immature green turtle swimming a few metres from shore (CTagg)
Adult turtles on very rare occasions can be seen mating in the sea. On the morning of the 21st of May, Conservation Officer Chris Tagg observed a mating event in the shallows at the south end of Bois Blanc. The mating couple were a few meters from the shore with at least another five males in the vicinity vying for an opportunity to mate with her as well should the mating male be displaced. To ensure he does not slide off or get washed away from the female, the male turtle will secure himself with his front flippers.  The next day, Conservation Officer Juan Michel spotted them again still in the process of mating!

Photo set: Top Male mounting female during breeding attempt with a second male bottom circling nearby (CTagg)

Events such as mating and high levels of emergence are signs for optimism in these times when conservation is fighting to change people’s perspectives on wildlife and the natural world in general and open their eyes to the impacts we are having on the Earth.

It is hoped that each island here in the Seychelles will have some form of protection or a dedicated team to monitor the turtles. Protecting one island on a chain is good but having some form of protection across multiple is excellent! If you would like to help in any way to the conservation efforts on Denis Island, report turtle sightings to the conservation team.

Friday 22 September 2017

Manta rays at Denis Island

What are those big sea animals that looks like underwater war planes? They are pelagic fish and one of the most intriguing species; in fact this spectacular animal is highly tolerant towards humans.

Mantas are here again this year, actively feeding in the shallow waters of Denis Island. From late August a few mantas have been sighted, either by diving hotel guests or by the Denis Island diving and fishing team. An encounter with these amazing creatures is purely fortuitous and never fails to amaze those lucky enough to experience it.

The arrivals of mantas at Denis Island correspond to the abundance of food availability. More recently, all along the northwest beach line of Denis island, washed-up zooplankton has been encountered suggesting its abundance in the region.
Mantas are warm water creatures that swim with their large pectoral fins. They have no venom or spine so they are relatively harmless. There are two species of manta rays. The giant manta (Manta birostris) commonly has a wing span of 4.5m (15 feet) but individuals of 9.1 m (29 feet) have been recorded, and it can weigh up to 3 tons (6,600 pounds. The reef manta (Manta alfredi) is smaller (max disc width recorded: 5 m or 16 feet) and it is commonly found in inshore habitats.
The presence of reef manta rays contributes to eco-tourism in certain areas where divers and snorkelers have the opportunity to dive in close proximity to these majestic fish. However manta rays face a huge number of threats such as fishing (both directed and bycatch), habitat degradation, global warming, pollution, ingestion of micro plastics and poor protection status in most regions of the globe. The IUCN Red List has categorized mantas rays as “vulnerable”.
The Manta Trust investigates movement patterns, feeding ecology and demography of reef manta rays in the Seychelles region. By doing this, we hope to gain a better understanding of the health and size of this manta population, as well as where, how, and why these animals move through the various habitats available to them.
Lauren Peel, a PhD student from the University of Western Australia and associated with the Save Our Seas Foundation/Manta ray project in the Seychelles, is very interested in setting up collaborations with researchers and dive shops across the Seychelles in order to get them to report sightings of  manta rays. This will  be with the aim of obtaining an outlook of their distribution and movement patterns. Individual mantas can be identified through the unique pigmentation patterns on the ventral side of their bodies and it is relatively easy to collect ID photos of them by free-diving down in front of them as they approach and take a photo as they swim overhead.

Recently a video of a manta feeding event occurred in Denis Island was recorded, and allowed us to identify two new manta rays and add them to our database. This is very exciting as we previously did not know that mantas were sighted in this area!

Friday 1 September 2017

North island myna eradication project as told by Claire and Sarah

What is the Common Indian Myna (Acridotheres tristis)? The myna is a bird native to India and South East Asia which has been introduced to various countries around the world. The myna was introduced to the Seychelles potentially to manage the number of insects damaging crops and other vegetation, however this is not confirmed. Is is an aggressive bird that has been known to injure and kill endemic birds as well as damage the eggs.  This has had a severe impact on breeding success and population numbers of endemic species across the islands.

North Island is working towards restoring the island to how it was before it became a farm for fruit, vegetables and coconuts in 1826. Removal of the myna is a huge step in this process and once completed endemic species can then potentially be reintroduced. The Myna Eradication Programme is a partnership of North Island, Green Island Foundations, Chris Feare of Wildwings Bird Management and endorsed by Ministry of Environment,Energy, and Climate Change.  The current programme commenced May 2016 and has since removed 924 myna from North Island.

Photo: partial view of North island seen spa hill  (CWaters)

Our current volunteers, Claire Waters and Sarah Atkinson took over in April 2017 for the final stages of the eradication. We are now reaching a very exciting part of the project where we are starting to see huge progress and can see we are reaching the end of the eradication process. The eradication of the myna has been successfully completed on two other islands in the Seychelles archipelago (Fr├ęgate and Denis); which have shown a notable dramatic increase in the native bird population on those islands. The eradication of the majority of mynas on North Island is already benefiting the native species on the islands and is thus proving its conservation importance.

In order to remove the myna, the methodology has changed since the beginning of the project to adapt to the birds’ changing behaviour. In order to be successful in removing the mynas, efforts need to be invested in understanding the bird behaviours and adapting methodologies accordingly. We are now in the process of carrying out surveys throughout the day to locate the remaining birds, which are thought to be in very low numbers.

So what do we do every day? Each day starts at 5:30am where one of the two Myna Eradication Officers, Claire or Sarah, start with a dawn survey at various locations across the island. This involves listening and looking for a dawn chorus, which is easily distinguishable from other birds around the island. Surveys then continue throughout the day, tracking the remaining birds and covering all areas of the island, from the plateaus to the top of the hills along the hiking trails. The other volunteer will begin work at midday, and will carry out the same survey at dusk to locate the birds as they select a tree to roost in overnight.
Photo: Sarah and Claire observing mynas (ASanders)

Interestingly, a previous Myna Eradication Programme on Denis Island found that the myna would roost in one tree together overnight. This has also been suggested to take place around the world. However, on North Island the myna have all been found to roost in pairs across the island. This is one example of the differing behaviour found in the myna on North Island and has made the project more challenging.

It has been found that as the number of myna on the island has dropped significantly, their behaviour has begun to change as well. Their vocalisations have altered to mimic native birds making it more difficult to locate them. This may be in response to low population numbers or in an attempt to disguise themselves. It is also possible that juveniles are learning from native birds in the absence of many adults to learn from. They have also become less confident and are no longer seen on the ground of the plateau. In the coming months, as we near completion of the eradication, there will then be an observation phase of the project, where the island will continue to be surveyed daily to ensure that we have eradicated all birds, this may take place for up to 6 months.

Since the start of the myna eradication, North Island staff have already noticed a significant increase in the numbers of endemic species. This includes the Seychelles Blue Pigeon (Alectroenas pulcherrima) and the Seychelles Sunbird (Necttarinia dussumieri) and is a huge positive step in restoring the island and conserving the unique wildlife of the Seychelles.

Photo: Seychelles white eye on North island (CWaters)

Saturday 19 August 2017

Rabbit fish research at Denis island

Rabbitfish are the main targeted fish species of the artisanal fishery of Seychelles, consisting of approximately two-thirds of the total annual catch. They are herbivorous and have been shown to help keep reefs healthy by grazing on invasive algae. With such commercial and environmental importance, Ameer chose to dedicate his PhD research to investigating the role that rabbitfish play in a marine environment, and their contribution to the resilience of tropical coral reefs. His research is crucial to small island states like Seychelles, as these regions rely heavily on tourism and fisheries for sustenance.

Ameer is currently conducting research on Denis Island for the fourth part of his thesis. He is specifically investigating the diurnal home range of rabbitfish around Denis Island and what factors, including tidal phase, habitat type and complexity, influence their movements.

                                    Photo (AEbrahim): Ameer conducting research in lagoon at Denis 

Denis Island has two very distinct habitats: vast corals reefs and lush seagrass meadows. Research from other parts of the world is increasingly demonstrating that coastal habitats, such as coral reefs, do not function in isolation but rather as part of a larger habitat network.  Other habitats such as seagrass meadows lie in close proximity to coral reefs, allowing for reef dwelling organisms and materials to travel among these habitats. Numerous species of commercially important herbivorous reef fish, such as rabbitfish, may frequent these habitats through diurnal and tidal fish migrations.

Accordingly, Ameer has dispersed 34 acoustic receivers encompassing the seagrass meadows and coral reefs in both shallow and deep water environments around Denis Island. Each receiver has a range of approximately 250m, allowing them to track the rabbitfish that Ameer has tagged using internal acoustic tags.

                                   Photo (AEbrahim): Placement of acoustic tags 

In many regions of the world, including Seychelles, connected habitats like seagrass meadows are often forgotten when it comes to conservation management. Therefore, this part of Ameer’s PhD will also assist in determining whether rabbitfish are frequenting different habitats such as seagrass meadows, thereby aiding conservation management efforts. Furthermore, his research will hopefully help cement future marine conservation management for the waters surrounding Denis Island. He is now in the process of collecting his data for this research.