The invasive snakes already occupy 90% of Ibiza and threaten to extinguish the Pitiusan lizard
The research confirms that these snakes are capable of swimming in the sea and are also extirpating populations on nearby islets
PalmaAn investigation led by the Center for Ecological Research and Forestry Applications (Creaf) warns that the horseshoe snake (Hemorrhois hippocrepis), an invasive snake that already occupies 90% of Ibiza and can swim to the islets, "threatens" to extinguish the Pitiusa lizard (Podarcis pityusensis).
The research, published in Ecology, states that these snakes "have not only devastated" the lizards on the main island, but also, because they are capable of swimming in the sea, are also extinguishing populations with unique colorations on the nearby islets.
The study analyzes the evolution of the horseshoe snake invasion in Ibiza, a species that arrived on the island almost 20 years ago through the importation of olive trees and has also been detected in Formentera.
The researchers, who have been carrying out this work for six years in the Balearic Islands, point out that the Pitiusa lizard has suffered a "drastic reduction" in the last 20 years and could disappear entirely from the island.
To carry out the study, in the case of the islet of Santa Eulària, 12 traps were installed and up to 58 snake specimens were captured between 2023 and 2025; they also compared lizards observed in the same transects – virtual fixed strip used for research – with a census from 2016: While 72 lizards were recorded that year, only three were detected in 2023 and none were observed in 2025.
Thus, they have confirmed the extinction of this lizard's populations on a dozen islets, including Santa Eulària and l'Ora. As these are small islets, this extinction occurs very rapidly, because, as they explain, just a few snakes can end the entire population in a matter of a few months.