At first glance, Sombrero Island doesn’t look like a place where life thrives. The surface of this tiny, remote, windswept land mass, 54km north-west of the Caribbean island of Anguilla, has an austere, moon-like appearance, with white-grey rock, strewn rubble and gigantic craters that are an uncomfortable reminder of the phosphate mining that devastated and permanently altered its landscape.
The remains of the old lighthouse and other abandoned buildings are windowless, weathered and worn, giving the impression of a ghost island. There are no trees, and vegetation is scarce, with little soil for anything to grow. Indeed, Sombrero Island – which forms the heart of the Sombrero Island Nature Reserve Marine Park – was on the verge of total ecological collapse.
Look at a picture of the island now and it’s a different story. Vegetation is returning and conservationists have recently celebrated a big win: a survey of the island’s endemic and Critically Endangered Sombrero ground lizard has revealed that the population has rebounded to more than 1,600 individuals, from fewer than 100 in 2018.
“We are ecstatic,” says Farah Mukhida, executive director at Anguilla National Trust. “These gorgeous little lizards have gone through so much. All the effort we’ve put into conservation has been worth it.”
The decline of Sombrero lizards
The Sombrero ground lizard’s island home was once a natural paradise with abundant tree cover and enough vegetation to support its own endemic giant tortoise (Chelonoidis sombrerensis), plus a medley of other wildlife.
This diversity nosedived following the discovery of phosphate deposits on the island by a British geologist in 1811. For the remainder of the century, this small rocky outpost was heavily mined by the Americans and British. Up to 3,000 tonnes of phosphate was harvested per year, much of it destined for use as fertiliser.
Christopher Columbus first set eyes on Sombrero during his second voyage (1493-96), and it’s thought the island was named by the sailors onboard due to the fact that, viewed from the side, it resembled a hat, with a long flat rim and a hump, or crown, in the middle. “That was destroyed when phosphate mining began, as the island was blasted out with dynamite,” says Mukhida. The ‘hat’ quickly crumpled and flattened, and the island became deforested.
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The rapid degradation of habitat was compounded by the introduction of invasive species, particularly mice, which were brought to Sombrero via ships. Not only were the lizards having to cope in a radically altered landscape but they were also now faced with predators that voraciously took their eggs and young.
If all that wasn’t enough, the species has also had to contend with climate change, which has brought increased hurricanes, storms and giant waves that crash over the island, as well as exposure to longer periods of drought. “In 2018, there was a severe sea swell,” says Mukhida. “The island was in ruins. We thought that might be the end.”
How on earth did this little lizard manage to cling on in such a bleak, inhospitable outpost? “They’re very resilient little creatures,” says Mukhida. “Some vegetation survived, especially around the ruins of buildings, and that has really helped, as it attracts insects, which the lizards eat.”
What are Sombrero ground lizards?
The Sombrero ground lizard is found nowhere else on Earth. It measures around 15cm, including the tail. Its correct scientific name is Pholidoscelis corvinus but previously Ameiva corvina was used, from the Latin corvinus, meaning ‘raven’.
“The lizards look jet black from a distance, standing out like silhouettes on the white rocks of Sombrero, but their scales are tinged with blue,” says Jenny Daltry, Caribbean alliance director for international conservation organisations Fauna & Flora and Re:wild. “It would be hard to imagine the island without its miniature Komodo dragons. They usually keep a watchful distance from people until there’s food around, then they fall over one another in an unseemly scramble to gobble down as much as they can.”
The lizards feed on almost anything from fruit to fish. Though they congregate around food, they are highly territorial. Males may share territories with several females but chase away smaller males, with juveniles usually exiled to the poorest corners of the island until they’re big enough to stake a claim to their own territory. Ground lizards don’t show any parental care: eggs are laid in warm soil and juveniles must fend for themselves after hatching.
Rewilding Sombrero Island
Restoration work on Sombrero Island began in 2021. A team from the Anguilla National Trust, along with Fauna & Flora and Re:wild, started to painstakingly ‘regreen’ the island with native plants such as sea bean, sea grape and prickly pear, and to eradicate non-native rodents using a grid of more than 1,000 bait points. “This was not an easy feat, on such a remote and rocky location,” says Mukhida.
By the end of 2024, Sombrero was declared pest-free. In just three years, the island had become visibly greener, with the reintroduced plants already showing healthy growth. Biosecurity monitoring will remain in place to make sure rodents don’t regain a foothold.
“We’re giving not just the lizards a better chance of survival but everything else that lives on or visits Sombrero,” says Mukhida. These include other rare and endemic species, including the Sombrero Island bee, the Sombrero Island dwarf gecko and the fearsome-looking, but harmless, Sombrero Island wind scorpion, plus several species of nesting seabird, such as the brown booby, masked booby, bridled tern and brown noddy.
Rewilding is a slow and painstaking process, and change won’t happen overnight. Long-term, Mukhida hopes to see at least double the number of different plant species growing on the island. “Vegetation recovery would provide foraging habitat and shelter for the lizards, but will also encourage other species. It would be great to have more terrestrial birds, more insects and more biodiversity,” she says.
The dilapidated buildings may also be repaired, which means the island could host students and researchers from Anguilla and around the world, as well as “very bespoke, niche tourism” in future. “Sombrero is so beautiful and different from anywhere else around,” says Mukhida. “Things would have to be done in a controlled, sensitive way, because we don’t want to set back any of our successes.”
The lizards have an important role to play in the natural balance of Sombrero. As well as providing a food source for species higher up the food chain, they offer pollination and pest-control services and clean up the carcasses of dead chicks and other waste from local seabird colonies. “But restoring the species is also about Anguilla’s wild heritage,” says Mukhida. “Anguilla’s offshore islands are biodiversity hotspots.”
Invasive species in the Caribbean
Sombrero isn’t the first site in Anguilla to be turned around. Anguilla National Trust, Fauna & Flora and other partners have worked on six other locations in the past 12 years, including Dog Island, East Cay and Mid Cay, East Prickly Pear and West Prickly Pear, and Fountain Cavern National Park. Other potential locations are now under consideration.
The Caribbean is one of the world’s most biodiverse areas, home to more than 10,000 species that occur nowhere else on the planet. Yet the region has also suffered some of the highest extinction rates in modern history. Caribbean islands represent just 0.16 per cent of the Earth’s land area but have accounted for 10 per cent of the world’s bird extinctions, 38 per cent of mammal extinctions and more than 65 per cent of reptile extinctions since 1600, with habitat loss, invasive species and climate change all key factors.
Around 40 Caribbean islands have been rewilded to date. Of these projects, 30 were co-led by Fauna & Flora, whose work started in the mid-1990s with efforts to secure the survival of what was then the world’s rarest known snake, the Antiguan racer, by removing invasive rats from Great Bird Island.
“As soon as we removed the rats in 1995, the snake population more than doubled and we were able to successfully reintroduce the species to several more islands,” says Daltry. “To our amazement, Great Bird Island exploded back to life and became full of birds, insects and plants. It was a beautiful lesson and an inspiration to rewild more islands.”
More Caribbean restoration projects are in the pipeline, including on Jamaica’s Goat Islands and Great Tobago in the British Virgin Islands. “There are more than 1,000 Caribbean species facing extinction, and we’re trying to help as many as we can,” says Daltry.
Among those at highest risk, with fewer than 100 individuals left in the wild, are the mountain chicken (a gorgeous plump frog about the size of a guinea pig), the elegant Saint Lucia racer snake and the magnificent carossier palm of Haiti.
Other priorities are the keystone species that are especially important for creating and maintaining healthy ecosystems, such as native crocodiles, iguanas and sharks. “Seabirds deserve special attention, too,” adds Daltry, “because of how important they are for boosting the growth of mangroves and coral reefs, and increasing fish populations.”
Daltry is keen to see more education and training, especially for locals, so that there are “more people with the skills to restore ecosystems and wildlife populations,” as well as more support from private landowners and, crucially, additional funding. “Rewilding islands is not cheap but there is nothing more rewarding than seeing them come back to life,” she says.
“The work on Sombrero has been immensely beneficial and has enabled a remarkable turnaround for its charismatic lizard. But there are as many as 10,000 islands in this region, most of which have invasive rodents and other introduced pests. There is plenty more to do.”
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