EU funds help SIF tackle invasive species threat |25 June 2012

SIF, which is responsible for the management and conservation of the Vallée de Mai and Aldabra Atoll, received the funding to address the problem of invasive alien plant and animal species which either already occur at the World Heritage sites or present a threat to the sites and the unique biodiversity they contain.

Running over four years, the project seeks to safeguard native ecosystems and endemic species (that is, species found naturally only in one location) by removing or preventing the spread of invasive species, which have been intentionally or unintentionally introduced from other countries.

Work is being conducted on Mahé, Praslin and Aldabra to combat invasive species, but one of the largest currently active elements of the project is being undertaken on Assumption.

The nearest island to Aldabra, Assumption is currently home to two different species of invasive bird, the red-whiskered bulbul and the Madagascar fody. Their presence on Assumption has long been considered a serious threat to the birdlife of Aldabra, which is renowned for being one of the largest islands in the world with no invasive alien bird species.

A team of SIF and Island Conservation Society staff has been at work on the island since late 2011 and has already succeeded in removing almost 50% of the estimated total population of invasive birds.

“The team have been working incredibly hard in very tough conditions to catch and research the invasive birds on Assumption. Thanks to their dedication and the invaluable assistance of the Island Development Company, Island Conservation Society and EU the work is progressing well,” said SIF chief executive Dr Frauke Fleischer-Dogley.

The urgency of the project has been thrown into focus by the alarming recent discovery of the Madagascar fody and red-whiskered bulbul on Aldabra. Small populations of the invasive birds have been found on the south west corner of Aldabra, at the closest point to Assumption.

Initial SIF estimates suggest that there are very few red-whiskered bulbuls on Aldabra but that there are over 100 Madagascar fodies, which are already well established and breeding on the atoll.

“From the size of the population and the fact that they have started to reproduce, we estimate that they made the crossing to Aldabra more than twelve months ago. This clearly demonstrates the timeliness of the project on Assumption and the need for success,” said Dr Fleischer-Dogley.

In this case the activities under the wider project sensitised staff to the risks and hopefully enabled sufficiently early detection of this invasion for eradication on Aldabra to be successful.

SIF is currently conducting a thorough assessment of the number of invasive birds and the area covered, before embarking on an eradication campaign on Aldabra.

“Working to remove invasive species, especially bird species, can be incredibly difficult, time consuming and expensive. Once we have a clearer understanding of the extent of the problem we face we will be better able to decide how to tackle it,” she said.

The arrival of the invasive bird species has occurred as SIF enters the final stages of a five-year project to eradicate goats from Aldabra.

Introduced to the atoll by early settlers, the goats have presented a serious problem for the atoll’s endemic giant tortoise population due to competition for food.

SIF has led a 30-year campaign to eradicate goats from Aldabra and the EU is now funding the last phase of this project. With just a few remaining goats to be monitored and eradicated, SIF hopes to be able to declare Aldabra goat-free by the end of the EU-funded four-year project.