Tom Ewart Smith
THE Balearic Islands have launched an emergency operation to tackle the spread of invasive snakes.
The decision comes after researchers from the University of Oxford made a concerning discovery on the protected islet of Sa Dragonera.
At the end of April, a camera trap placed by Oxford scientists – who were monitoring nests of the endangered Balearic shearwater (Puffinus mauretanicus) – captured the first image of a horseshoe snake (Hemorrhois hippocrepis) on the islet.
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The sighting triggered an immediate response from the Regional Ministry of Agriculture, Fisheries and the Environment, which warned of the snake’s potential to cause ‘serious problems’ to the fragile local ecosystem.
“Invasive snakes, in environments as fragile as the islands, can pose a serious problem,” said Anna Torres, Director General for the Environment and Forest Management.
She added that it was vital ‘to safeguard protected and endangered species that could be affected by the presence of invasive snakes.’
The campaign, led by the Consortium for the Recovery of the Fauna of the Balearic Islands (Cofib), aims to determine the extent of the invasion and protect the native fauna.
This involves 95 traps being installed, with 85 across the islet, seven along the nearby Mallorcan coastline, and three on the islet of Es Pantaleu.
All traps are georeferenced, regularly checked by technicians, and placed away from public footpaths.
The operation comes as part of a wider concern about the growing dominance of horseshoe snakes in the Balearics – particularly in Ibiza, where the native Pitiusa lizard (Podarcis pityusensis) is at risk of extinction by 2030.
Introduced to the island in the early 2000s, the snakes have flourished due to a lack of natural predators and an abundance of prey.
Biologist Jaume Estarellas has warned of the unusual growth of Ibiza’s snake population, noting that ‘gigantism’ has become common.
In 2013, a record-breaking individual measuring 183 centimetres was captured, far above the species’ average length of 89 centimetres.
Despite ongoing efforts, including a 2024 campaign that removed nearly 500 snakes and added 280 new traps, the situation remains critical.
The Institut d’Estudis Eivissencs has described the invasion as ‘practically unsolvable’ and said that actions taken so far ‘have not been sufficiently successful.’
