Rewilding Sombrero Island from the Brink of Ecological Collapse

We are in the middle of a biodiversity crisis. Animals, plants, and other species are fighting for their continued survival against climate change and environmental degradation caused by human activities. As the thriving coexistence between humans, biodiversity, and ecosystems is key to a healthy planet, conservation and restoration efforts are underway worldwide. In the Caribbean, local and international actors have been working together to bring Sombrero Island back from the brink of complete ecological collapse.

Biodiversity Hotspot, Threatened

The Caribbean is in the top three of Earth’s biodiversity hotspots, with over 10,000 endemic species. Tragically, the region has accounted for 10% of bird extinctions, 36% of mammal extinctions, and over 65% of reptile extinctions since the 1600s.

Sombrero Island is a tiny, uninhabited 38-hectare of rocky area in Anguilla. It is home to several endangered species that do not exist anywhere else, such as the Sombrero ground lizard, dwarf gecko, bee, and wind scorpion. Sombrero Island is also an important breeding site for various seabird species, including the globally significant brown booby and bridled tern.

What happened? In the 1800s, the British and Americans exploited Sombrero Island for its guano, seabird excrement rich in phosphate and used for fertilizer. By 1890, they had exhausted the guano reserve due to extensive mining. Besides thorough deforestation and ecosystem degradation, the mining operation also brought an invasive species to the island: mice.

Additionally, Sombrero’s biodiversity faces threats from climate change. Dr Jenny Daltry, Caribbean Alliance Director, said, “The Caribbean has contributed little to the global causes of climate change but it is already suffering from its effects. Extreme weather events are becoming increasingly severe, with the past five years seeing some of the worst hurricanes ever recorded.”

While native species may cope with the storms and hurricanes, mice upset the ecological balance. These invasive species eat native reptiles, insects, and seabird eggs as well as seeds and roots of plants that should grow into their habitats. These intersecting factors have brought Sombrero Island to the brink of complete ecological collapse.

Sombrero Island Restoration Efforts

In 2021, a conservation project led by local Anguillan conservationists (Anguilla National Trust) and a Caribbean Alliance (from Fauna & Flora and Re:wild) began. To start, they focused on eradicating invasive mice and finally declared the island pest-free the following year.

Without mice, native species have the chance to rebound. For instance, the Sombrero ground lizard population rose from 100 to more than 1,600 in December 2024.

However, the threat of more frequent and extreme hurricanes and storms remains. To improve climate resilience, conservationists aim to help the recovery of Sombrero’s natural vegetation by planting native plant species. So far, native plants such as sea bean, prickly pear, and spider lily are showing healthy new growth.

“These restoration interventions have cascading effects: they attract insects which help pollinate plants, they attract birds that drop seeds, they provide food and shelter for lizards that also serve as seed dispersers, pollinators, and nutrient transporters,” said Farah Mukhida, Anguilla National Trust Executive Director.

The efforts do not stop here. The conservation team promises to maintain constant vigilance in case of more invasive species. They also plan to continue the rewilding efforts by planting more vegetation and building soil reserves.

“We’re committed to Sombrero’s recovery, sharing lessons learned, and building on successes,” said Mukhida.

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