Research led by the Centre for Ecological Research and Forestry Applications (CREAF) has warned that the spread of the horseshoe whip snake poses a serious threat to the survival of the Ibiza wall lizard on Ibiza and its surrounding islets. According to the study, published in the scientific journal Ecology, the invasive snake now occupies almost 90% of Ibiza’s territory and is even capable of swimming to small offshore islets where unique populations of the native reptile still survive.
Researchers say the presence of the snake has not only caused a sharp decline in lizard numbers on the main island, but has also led to the disappearance of specimens with distinctive colour patterns on nearby islets. The invasive species first arrived in Ibiza nearly two decades ago through the importation of ornamental olive trees and has since also been detected in Formentera.
The scientific team has spent the past six years studying the evolution of the invasion in the Balearic Islands and concluded that the Ibiza wall lizard has suffered a “drastic reduction” over the last two decades, to the point where it could disappear entirely from Ibiza.
One of the areas examined was the islet of Santa Eulària, where researchers installed 12 traps between 2023 and 2025 and captured 58 snakes. Comparative data revealed the dramatic collapse of the lizard population: while 72 specimens were recorded along the same transects in 2016, only three remained in 2023 and none were detected in 2025.
The study also confirmed the disappearance of the Ibiza wall lizard from around 10 islets, including Santa Eulària and s’Ora. Scientists warned that in such small environments, only a handful of snakes are needed to wipe out an entire lizard population within a matter of months.