Snakes Swim to Islets, Threatening Lizards

Why this is here: The researchers estimate the time it takes for a snake to completely wipe out a lizard population on a newly colonized part of Ibiza has decreased from eight to ten years to just three to two years.

Scientists at the CREAF in Spain document how horseshoe snakes are swimming to small islands off Ibiza to prey on the unique Pitiusan lizard. Researchers observed and recorded a snake traveling 430 meters by sea to reach an islet, confirming earlier reports from locals. These snakes, originally from the Iberian Peninsula and North Africa, arrived in Ibiza in 2003 via plant nurseries.

The lizards, found only in this region of the Balearic Islands and nearby islets, have already disappeared from ten of these small islands. The snakes establish a “front of invasion,” quickly depleting food sources and then swimming to new locations. Despite removing over 12,000 snakes since 2016, they now occupy roughly 90% of Ibiza and continue to colonize islets.

CREAF is currently capturing lizards and transporting them to the Barcelona Zoo—creating a sort of “Noah’s Ark”—while they develop a long-term conservation strategy. The loss of these lizards could destabilize the island’s ecosystem, impacting insect control, pollination, and seed dispersal.