Redonda rescue — saving its native species | Green

Tiny Redonda, with its steep and barren cliffs, is home to colonies of seabirds, rare lizards found nowhere else — and, until recently, hordes of invasive goats and rats. But a new restoration project aims to return Redonda to its original inhabitants. Erline Andrews learns more

Ameiva atrata is a ground lizard endemic to Redonda. Photo courtesy Jenny Daltry/Fauna and Flora InternationalRedonda is a prime nesting site for brown boobies and other seabirds. Photo by Martin Michael Rudlof/Shutterstock.com

The dwarf geckos of Redonda, Sphaerodactylus sp, are among the rarest creatures on earth. About an inch long, on average, with translucent brown skin spotted white and bulging eyes, they can be found only on the one-mile stretch of mountainous island that Columbus mistakingly thought was round — hence his name for it: Santa María de la Redonda. Today, uninhabited Redonda in the Leeward Islands is part of Antigua and Barbuda, though it’s closer to St Kitts and Nevis.

Researchers think the geckos meet the criteria to be on the list of critically endangered species. Their numbers were reduced by the destruction of their habitat by invasive species — rats and goats — brought to the island more than a century ago by humans. But now people are racing to reverse the damage and save the dwarf gecko and two other lizard species endemic to Redonda. A ground lizard, Ameiva atrata, long, glossy black, and described as fearlessly inquisitive by researchers, is listed as critically endangered. And a tree lizard, Anolis nubilis, which has few trees left to climb and actually lives mainly between the rocks of the almost barren island, is for the time being listed as stable.

Redonda is also the nesting place for hundreds of seabirds. According to a 2012 survey, more than fifty per cent of masked boobies — the largest booby species, distinguished by a dark grey face that contrasts with a mostly white body — in the Lesser Antilles nest on Redonda. And more than twenty per cent of the breeding pairs of the region’s brown boobies — large, long-billed birds with a white, feathered bib extending from chest to belly — use Redonda, along with twelve per cent of magnificent frigate birds.

Two animal species have apparently already disappeared from the island: the burrowing owl and a skink (another kind of lizard) that was endemic to Redonda. “I’ll never get to see all sorts of wonderful animals because the previous generations didn’t care, they didn’t take action,” says conservation biologist Jenny Daltry, one of the key forces behind the Redonda Restoration Programme. “I don’t think we have the right to let these go without making some effort.”

Daltry works for UK-based Fauna and Flora International. The oldest global conservation organisation, FFI has restored twenty-four islands in the Caribbean, including protectorates of Barbados, St Lucia, and Anguilla.

Daltry first came to Antigua and Barbuda in 1995, to help save the Antiguan racer, a venomless snake endemic to the country that was on the brink of extinction. Only about fifty remained on uninhabited Great Bird Island. The Antiguan Racer Project proved successful, and grew into the Offshore Islands Conservation Programme, which worked to save the wildlife and vegetation on fifteen islands in the Antigua and Barbuda chain.

The Caribbean region has one of the highest rates of species extinction, Daltry pointed out in a 2015 presentation. She traces the problem back to when Europeans first came to the region. Rats stowed away on ships. Goats were brought to Redonda to provide meat and milk for miners who lived there between 1860 and the First World War, extracting guano. Elsewhere in the region, mongooses were brought from Asia to deal with the rats, but turned into pests themselves.

“Some people would say, why are people from England getting involved in this? Well, actually a lot of problems you have — the rats, the goats, and the mongooses — to be honest, it was the English people that brought these things here,” explains Daltry. “As an English person, I have a responsibility to try and help.”

Invasive species are also a problem in inhabited areas, but uninhabited islands promise long-term success in providing a safe haven for wildlife. “What is exciting about some of those little offshore islands is that you can actually turn back the clock and help wildlife recover,” says Daltry.

 

When researchers visited Redonda in 2012 to do a feasibility study, they estimated a rat population of around 5,500. Individual rats live only about a year, but they reproduce relentlessly.

In the stomachs of rat specimens, researchers found plant, bird, egg, and lizard remains. Demonstrating the extent to which rats consume anything in their path, they were also found to have ingested goat droppings — and other rats. If rats caught in traps weren’t retrieved quickly enough, researchers would find them partially eaten.

“Those rats over there were so intelligent,” says Antiguan ecologist Shanna Challenger, who heads the Redonda programme. “They would work in teams. I’ve seen two of them — one would distract the bird and the other would roll the egg from underneath it.”

To put together the feasibility study and spearhead the rat eradication, the Redonda team recruited Elizabeth “Biz” Bell, an ecologist from New Zealand. “Invasive rats have caused mass extinctions of spectacular creatures around the world,” says Bell. “New Zealand is one of those places, and this is why we started developing these techniques to remove invasive species and spread that technology around the world to help other countries.”

The intricate rat eradication process was laid out in the 2012 feasibility report. Fund-raising took years. The mission, which cost an estimated US$700,000, brought together an impressive coalition, including Antigua and Barbuda government agencies, the local conservation NGO Environmental Awareness Group, Caribbean Helicopters Ltd — helicopters are the only way to access Redonda — and the British Mountaineering Council, who helped lay rat poison around the island’s steep cliffs. UK charities the Darwin Initiative, the National Fish and Wildlife Foundation, and the Taurus Foundation provided funding.

The rat eradication began in January 2017 and was wrapped up by March. Around the same time, the sixty-five or so goats on the island, who were starving because of a lack of vegetation they helped decimate, were corralled and carefully airlifted to the mainland.

It will be months before Redonda can be declared rat-free. The island has to be regularly monitored over the next few years to make sure the rats are gone and to see how the wildlife and vegetation rebound.

“They’ve already started to notice some recovery in the bird population,” says Antiguan marine biologist Ruleo Camacho, another member of the restoration team. “Based on the recovery rates we’ve seen on some of the other islands where we’ve done rat eradications, bird life responds pretty quickly. You get quite a rapid recovery, not only in the number of birds but also in the diversity of bird species.”

Colin Donihue is one of a team of biologists from Massachusetts who volunteered to help monitor the lizard population over the next few years. “The problem is, a lot the islands are small, and that means the species on them are pretty vulnerable,” he says. “Severe weather or invasive species can easily wipe out an entire population on an island . . . When you lose a species that’s only on an island, you end up losing real richness and diversity.”

Public education is an important part of maintaining the restored islands, says Daltry. “When I first went to Antigua I spoke to a school class, and I said, ‘Where do wildlife live?’ And they said, ‘Oh, in Africa.’ Because they’d only seen naturalistic programmes about Africa and the lions and elephants,” she says.

“But there’s so many wonderful animals just under their noses,” she added. “They may not be as big, but they’re still very special and unique and important in their own way.”