Spanish researchers have confirmed the presence of horseshoe whip snakes on Santa Eulària, an islet near Ibiza, which poses a threat to the local wall lizard population. A video recorded in April 2024 showed the snake swimming between Ibiza and the islet, marking the first documented evidence of this behavior. The horseshoe whip snake, a nonvenomous species from mainland Spain, has been a significant threat to the endemic Ibiza wall lizard, which has seen its population decline dramatically since the snake's arrival two decades ago.
The snake's colonization has been linked to the importation of olive trees by property owners, which provide ideal habitats for the snakes. As of 2022, the International Union for Conservation of Nature classified the Ibiza wall lizard as endangered. The Balearic regional government reported capturing over 3,500 horseshoe whip snakes on the island last year, with forecasts suggesting they may occupy the entire island by 2027.
While a captive breeding program for the lizards has been initiated, the ecological impact of the snakes is significant, with researchers noting a drastic reduction in lizard sightings on Santa Eulària. The situation has drawn comparisons to the ecological crisis faced by Guam due to the introduction of invasive species. Despite these challenges, lizard populations in urban areas of Ibiza remain stable due to human intervention against the snakes.
