Feral control success in Seychelles

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Scientists believe the world is currently undergoing its sixth extinction, as a result of human activity that includes land clearing, pollution and overfishing. While mainland Africa has not lost a single known-bird species since 1600, Africa’s satellite islands tell a different story. One of the main causes of extinction is the presence of feral animals on islands.

A 2013 study by Canadian scientist Peter Blancher found that cats kill between 100 million and 350 million birds a year in Canada alone. But rats and dogs also play their part in the destruction of wildlife.

While island nations often struggle to control feral populations of cats and dogs, Seychelles is a positive example when it comes to the conservation of the islands’ indigenous species. Since the 1970s, Seychelles has been conducting habitat restoration projects that include eradication programmes for invasive species like rats, mice, myna birds, and feral cats.

Seychelles is now regarded as a world leader in the management of invasive species. “The achievements of Seychelles in terms of invasive species eradications, threatened species recovery and island restoration are exemplary, and set a high standard for the rest of the globe,” says Dr Nick Holmes of Island Conservation, an organisation working to prevent extinctions on islands.

Seychelles has focused on small islands with high biodiversity value. Between NGOs, privately owned island resorts and the government, Seychelles currently has 24 small to medium-sized islands that are free from rats and cats.

The removal of these invasive species has resulted in successful reintroductions and population growth of threatened bird species like the Seychelles warbler, Seychelles magpie-robin, Seychelles white-eye and Seychelles fody. The Aldabra giant tortoise has also benefited from 18 new introductions onto these islands.

The Seychelles sunbird is endemic to the island. Sketch: Graham Kearney

The Aldabra rail is the last flightless bird in the tropical western Indian Ocean and has only persisted on islands without cats, like Polymnie and Malabar. Once cats were removed from Picard, the bird was reintroduced there too.

Seychelles has successfully turned half of its terrestrial land into protected areas. Currently, 3.9% of the country is cat and rat free. The new goal is to make 5.4% of the islands free from feral cats and rats. Feral dogs do not fend well on remote islands or in areas uninhabited by humans. “Stray dogs are an issue both for marine turtles and mud terrapins,” says Dr David Rowat, chairman of the Marine Conservation Society Seychelles.

“Critically Endangered hawksbill turtles nest during the day, and we have had several instances of dogs attacking nesting females,” he says. Within the last century, the Marianne white-eye and Seychelles parakeet have become extinct, partly due to predatory invasive species.

Aldabra, as well as the large and densely populated Seychelles islands like Mahé, Praslin, La Digue and Silhouette are estimated to have hundreds of feral cats and tens of thousands of rats. On islands like Aldabra and Menai (Cosmoledo), the eradication of rats is not envisioned for the time being, due to the lack of effective techniques to remove rats from large extensions of mangroves.

– Information provided by Dr Gérard Rocamora, scientific director and chair of the Island Biodiversity & Conservation (IBC) centre at the University of Seychelles, and first author of Invasive Alien Species in Seychelles

Written by Georgina Lockwood

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1 Comment

  1. Ho hum… don’t know what to say. The cats will be easier to exterminate than the rats, and once the cats are gone – hoo boy! What people appear not to realise is that there are VASTLY more rats and mice than cats and that rats and mice kill as many birds and lizards and snakes and small mammals as cats do. Probably more. Watch the Marion Island space, guys!

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