Removal of invasive species transforms Redonda

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In July 2018, Redonda was officially declared as rat and goat free leading to a spectacular recovery of its native species.

Redonda

“This project was essential for the well-being of the goats and to enable the ecological recovery of the island. The translocation of goats has seen a suite of positive impacts, and further benefits will unveil themselves in time.”

Dr Karl Campbell; Island Conservation

Between them, goats and rats have been responsible for the decline of island species the world over. Goats were introduced by human settlers and rats found their way onto islands via visiting ships. In Redonda’s case it was black rats that invaded the island. They had a massive impact on the fauna and flora biodiversity, particularly on the reptile populations. As a result, all of the islands endemic lizards, including the Redonda ground dragon, are listed as Critically Endangered on the IUCN Red List.

The Redonda Restoration Programme is one of a number of such projects that have been introduced globally to protect island biodiversity. All face unique challenges. For this project it was not only the eradication of thousands of rats, but the safe removal of the of the goats. The Department of Agriculture had requested that the goats, which have been confirmed through genetic testing to be a rare feral breed of Spanish origin, be brought back to Antigua alive. The herd was suffering through malnutrition but most of them were successfully captured, by hand, and moved off the island. A move that has been beneficial to both them and the recovery of the island, as Dr Karl Campbell of Island Conservation confirms:

“This project was essential for the well-being of the goats and to enable the ecological recovery of the island. The translocation of goats has seen a suite of positive impacts, and further benefits will unveil themselves in time.”

 

Redonda
Black rat and booby chick, Redonda © Jeremy Holden, FFI

 

Whilst the rat removal was completed in June 2017, Redonda was only declared as ret-free in July this year. Final confirmation came after an intensive three-week survey failed to uncover and evidence of rats or signs of their existence anywhere on the island.

Since its restoration, Redonda has been transformed from an inhospitable lunar-type landscape to one rich in native plants and trees. Signs have also been seen that the reptiles are reverting to type as Dr Colin Donihue, of Harvard University points out:

“We measured anti-predator behaviour and found that the ground dragons are becoming fierce and fearless now that the rats are gone, chasing and eating even adult tree lizards. This new balance of nature is more in line with what we’d expect of these animals before rats were ever on the island.”

Redonda

“It’s incredible to see this radical and rapid transformation of Redonda from a bare rock to a carpet of vegetation. As plants and animals continue to rebound, this could truly be a showcase sanctuary for wildlife.”

Dr Robin Moore from US-based Global Wildlife Conservation

What has surprised the project team and supporters most is the speed of recovery of the island’s biodiversity. In less than a year, numbers of the rare Redonda tree lizard have tripled, hundreds of trees are growing, there has been a tenfold increase in land birds and the seabird colonies are showing significant signs of recovery.

Redonda was recognised as an Important Bird area in 2009 due to its regionally and globally significant colonies of seabirds including brown boobies, masked boobies, red‐footed boobies, magnificent frigatebirds and red-billed tropicbirds. Records have confirmed that 2018 is the best breeding year on record for these species.

Conservationists are not the only ones to recognise the importance of the island. A recent nationwide survey revealed that over 96% of Antiguans and Barbudans (Redonda became a dependency of Antigua and Barbuda in 1967) agree the island should be protected. Preparations for designating Redonda and the surrounding sea as a reserve are now under way, led by the Redonda Steering Committee, chaired by the Department of Environment. Speaking on behalf of the Department of the Environment, Dr Helena Jeffery Brown said:

“The Government of Antigua and Barbuda considers the return to life of Redonda as a shining beacon in our collective efforts towards ecosystem restoration and biodiversity conservation.

 

Redonda
Redonda ground dragon © Jeremy Holden, FFI

 

In conclusion, Dr Robin Moore from US-based Global Wildlife Conservation, which has supported this project and is now helping with planning for the protected area, comments:

“It’s incredible to see this radical and rapid transformation of Redonda from a bare rock to a carpet of vegetation. As plants and animals continue to rebound, this could truly be a showcase sanctuary for wildlife.”

The success of this project was due to the collaboration of a number of organisations (including the Government of Antigua and Barbuda, Environmental Awareness Group; and Flora and Flora International) and specialists from the UK, USA and New Zealand.