A tiny lizard found only on one tiny Caribbean island has seen a dramatic 1,500% increase in its population, after just a few years of island restoration efforts.
In 2018, researchers estimated there were fewer than 100 individuals of the critically endangered Sombrero ground lizard (Pholidoscelis corvinus) on the small hat-shaped Sombrero Island, part of Anguilla in the Caribbean. Just six years later, there are more than 1,600 of them, a recent survey has found.
“I am beyond thrilled to see the ground lizards on the road to recovery, and this is a fantastic reward for everyone who has worked hard to restore Sombrero,” Jenny Daltry, Caribbean alliance director at conservation NGOs Fauna & Flora and Re:wild, told Mongabay. “Too many island species have been lost already, and we really need to prevent extinctions whenever we can.”
Today, Sombrero Island hosts large seabird colonies and several unique and rare species. But invading mice, likely brought to the island on ships or other means by people, as well as climate change impacts, have wreaked havoc on the island’s inhabitants.
When mice take over islands, they devour almost everything, from seeds to seabirds, Daltry said. “By preventing plants from regenerating, the mice deprived the lizards of vital shelter and food, including fruits and insects. No doubt they also preyed on the lizards’ eggs and young.”
With native vegetation in a precarious state, storm surges and hurricanes striking the island further devasted the island’s lizard populations.
To turn things around, Fauna & Flora, Anguilla National Trust and Re:wild began restoration efforts in 2018. They trapped and removed all the mice by placing bait from June to August 2021. They also developed a “biosecurity plan” in which researchers regularly check the island to ensure it’s still mouse-free.
Given Sombrero’s remote location, the likelihood of reinvasion by mice is considered low, Daltry said. She added that the teams are also developing “remote surveillance cameras with AI capability” to automatically detect and alert them of invasive species.
While the mice may be gone, the threat from hurricanes fueled by climate change still loom close. While the researchers have been working to restore the island’s native vegetation, the island has lost much of its original soil cover, which will take time to rebuild, Daltry said. With no tree cover yet, any severe hurricane or storm surge in the future “could set back the speed of recovery of the soil layer and vegetation,” she added.
However, Daltry said she’s hopeful that even the current sparse vegetation provides the Sombrero ground lizards “with vital food and shelter, giving them a much better chance of survival when the next storm strikes.”
“This could make the difference between survival and extinction,” she said. “The big question is whether the recovery of Sombrero Island and its wildlife will be able to keep pace with the speed of climate breakdown.”
Banner image of Sombrero ground lizard ©️ Richard Brown/Fauna & Flora.
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