Lizards, birds and other species endemic to the tiny isolated island of Redonda have begun to flourish. The Caribbean territory is no longer overrun with thousands of black rats, and its moonscape terrain is recovering, yielding increasing greenery.
The transformation is a result of the work of a team that includes Cave Hill graduate
Shanna Challenger, Redonda Restoration Programme Coordinator.
The little-known, steep-sided Redonda measures about 0.5 square miles. Though it can be found between Montserrat and Nevis, it was declared a dependency of Antigua (50 kilometres away) by the British who made it a strategic acquisition. The seabirds that nested there produced vast quantities of guano, making Redonda the largest phosphate mining area in the region. Apart from being used for fertiliser, phosphate was a key ingredient in gunpowder production.
During that time, an estimated 150 people lived on Redonda, bringing to the island domesticated animals, including goats; rats were also brought inadvertently. When Redonda was abandoned by its human inhabitants, rats and goats were left behind.
By 2012, when conservationists visited the island, it was overrun by an estimated 6,000 rats, while there were about 50 long horned goats.
Redonda is an important island for biodiversity:
“They found new species of lizards. It was also an important area for birds globally because of the number of seabirds nesting there. It’s remote and a haven for wildlife. So, we really wanted to step in because it was being decimated by the rats and goats that were over there,” Challenger said in an interview with UWI TV.
This led to the
Environmental Awareness Group (EAG) and Fauna & Flora International (FFI) 
Redonda Restoration Project that sought to remove invasive species allowing the island’s ecosystem to recover and numbers of its critically endangered, endemic species, like the Redonda ground dragon, to grow.
“One of the biggest reasons we had to get rid of the rats was because of the decimation of the chick populations that we had. On Redonda, we have different species of nesting birds, red-footed booby, brown booby, masked booby, peregrine falcon, tropicbirds, frigatebirds; we have lots of birds. We think a lot of the birds had left because they weren’t having any hatching success because of the rats. The rats were so intelligent they would work in teams, and one rat would distract the mother bird while the other one would roll the egg from underneath her. The rats were also eating the lizards and goat droppings; they would even eat each other.”
Additionally, although the majority of the goats had survived the harsh climatic conditions on Redonda, overgrazing and lack of standing water were taking their toll:
“Every time we went back, we saw a number of different goat carcasses or they looked very small with their ribs showing. That is why we decided to embark on this goat relocation. The goats that were on Redonda have these large horns, not what you typically find in Antigua; and we really wanted to work along with the Ministry of Agriculture because they wanted to preserve that rare breed, so we brought them over in a helicopter.”
This proved a challenging initiative, particularly when dealing with the more aggressive male goats. After being lured with water into a corral, the goats were hobbled (the front and back feet tied together), hooded to keep them calm, and taken on a 20-minute helicopter flight to Antigua. On arrival, they received full check-ups and were microchipped for tracking and easy identification.
“When we brought over the goats, our intention was to mix them with the local breeds that we have in Antigua so that those goats could somehow get the climate change-resilient genes. But we’re also keeping the gene pool separate to maintain our Redonda goats as they’re called. They’re doing pretty well now that they’re on the mainland. It took them quite a bit of time to acclimatise to their new environment, but it has been good.”
The rat eradication component also required time and proper planning. Challenger was stationed on the island for about a week in one instance, and days in others. Other team members stayed for three months.
“To get rid of the rats, we had a 1.5-litre bottle, and we cut off the ends to create a tunnel; then we wired in the bait, about four blocks. We put them down every night, waited and checked in the morning to see how much bait had been eaten. We did this every 30 metres. We basically covered the island in this way. In addition to being on the ground, we also had people abseiling, mountain climbers on the side of cliffs putting in the bait; and we had slingshots. We also had to go down to the coast, which took us about two hours, and put rat bait around the coastline as well. There were some areas that were inaccessible [by foot], so we had to swim across to them. We also [dropped bait from the air].
“Within the first week or so, we saw the [rat] numbers go down completely. After we put the rat bait in, we, of course, had to deal with the dead rats. The rat bait didn’t kill instantaneously but took three days to kick in.”
The carcasses were then collected, taken back to camp, measured, dissected to ensure they died from the bait, and studied.
The Cave Hill graduate said they found that 90 percent of the female rats were pregnant, about to go into heat, or lactating.
“If we had not struck while the iron was hot, then they would have just started another cycle of breeding,” she said.
The birds and other endemic species were safe during the baiting period because the poison used only affected mammals, the project coordinator explained. To prevent a resurgence of the rat population, regular checks are still conducted, and permanent bait stations were set up.
“Since 2013, we have wildlife monitoring data [collected from] the birds: how many of them were there, what times they were most active; as well as [data on] the lizards. We actually had people come in from Harvard and Yale - herpetologists to study the lizards; and they looked at their length, their diet, [and] their distribution throughout the island. So we have data pre-invasive species removal, and now we’re collecting [data] after [removal].
“We used to call it a moonscape because of how bare it was. But since we’ve done the conservation activities, we’ve seen the island looking much greener, more full of life; and we’re seeing species that we haven’t seen before.”
Challenger, who graduated with a BSc in Ecology in 2016, said the results have made the challenges she faced while studying worth it.
Though she was initially focused on being a doctor, the Antiguan discovered her love for diversity of life in her first year of studies, and subsequently switched her major. As a result, she lost funding for her government scholarship, Her decision was questioned by her mum, but she did not give up.
“I never felt bad about it. The other science majors said, ‘Oh, ecology isn’t even a real science degree. That’s what all the lame people do’. It was like, ‘Why did I do this?’ But I really enjoyed all of my courses. It was a lot, but it was definitely worth it. I had so much fun. Ecology was a fun degree because you get to do so many things.”
Professor of Conservation Ecology Julia Horrocks was her undergraduate advisor at Cave Hill. She thought Shanna was a perfect fit for the conservation post with the
Redonda Restoration Project and supported her employment with FFI. Challenger went to Cambridge, United Kingdom for training and has met the man described as the most famous naturalist on Earth, Sir David Attenborough, as well as Prince Charles and Prince Harry.
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