Snake invasion in the Balearics: “Not even an army could eradicate them”

A snake almost two metres long appears on a beach. All the bathers flee the water in fear. What might seem like an anecdote could become an increasingly common situation on the island.

“We have to learn to live with them. Not even an army prepared to wipe them out would manage it”, explains Samuel Pinya, professor of Ecology at the University of the Balearic Islands, who uses military language because the threat is highly significant: “In the long term, it will lead to a complete destabilisation of the ecosystem”.

It is clear that they are spreading across the island and its islets. This is reflected in data provided by the Consorci per a la Recuperació de la Fauna de les Illes Balears, COFIB, an organisation under the Regional Ministry of Agriculture, Fisheries and Natural Environment. The increase in captures coincides with the strengthening of control mechanisms deployed in recent years, which show the species’ expansion across the island. There were 170 traps installed by the Administration. A year later, the figure rose to 280 specimens and 375 traps. So far in 2026, around 450 devices have already been deployed and 58 snakes have been captured.

“It has increased, yes, without any doubt”, says Pinya. The researcher recalls that some species introduced barely two decades ago are already appearing in areas where they were not previously present. “The horseshoe whip snake was not in the Serra de Tramuntana and I have found it in hidden places where you wonder how it got there”.

“They have no effective predators”

The explanation, he argues, lies in the biology of these reptiles. “The main reason is that they have no effective predators to control their expansion”. Although cases of North African hedgehogs capturing young horseshoe whip snakes have recently been documented, these natural mechanisms remain insufficient to contain the growth of the populations.

For years, their arrival with olive trees and other plants went unnoticed. “At first, it was not so noticeable. But when they start reproducing and there is no predator to control the populations, they grow and begin to colonise new territories because there is competition among them”, he says.

The greater presence of snakes in recent weeks is no coincidence either. “We are seeing them more now because it is mating season. The heat has increased, there is more reproductive activity and their prey is also more active. That is why they come out more”, Pinya explains. Added to this is the role of social media, which amplifies every sighting and increases the feeling that snakes are everywhere.

“The snake is a very efficient predator and has probably come to stay”, adds Andreu Rotger, professor of Biology at the University of the Balearic Islands. The researcher believes Balearic society will have to accept a new reality. “Perhaps we will have to learn to live with them. What we can do is control the populations. Achieving their eradication is extremely complicated”.

The consequences, which no one can yet predict precisely, are partly linked to the butterfly effect described through a metaphor by meteorologist Edward Lorenz: “The flap of a butterfly’s wings in Brazil can cause a tornado in Texas”. The idea is simple: a small alteration can end up triggering much larger and unpredictable changes. Scientists fear the consequences of the spread of invasive snakes in the Balearic Islands.

The example of the Ibiza wall lizard

For Rotger, the real problem is not occasional encounters on beaches, in gardens or in residential areas. The concern lies in the ecological impact. “At an ecological level, it involves many negative effects. On islands, relationships between species are more limited”, he warns.

He gives the example of lizards. On certain islets, they play essential roles in the natural balance. They control insects, disperse seeds and even take part in the pollination of some plants. “If snakes reach certain islets and wipe out lizard populations, we would lose a very important ecological function”, he warns.

Pinya shares this concern and broadens the focus. Snakes do not only prey on lizards. They also feed on birds, rodents, geckos and other reptiles. “We think about the impact on one specific species, but the problem is broader", he stresses, adding: “There are relationships that have not yet been documented and we do not know what the overall impact will be, but it will not be positive,” warns the Ecology professor.

Rotger defends the need to strengthen awareness campaigns and improve coordination between administrations and citizens. “Communication is fundamental. The sooner invasive species are detected and the sooner action is taken, the greater the chances of controlling their populations”.

Because if there is one thing scientists are clear about, it is that the battle is no longer about preventing the arrival of snakes. That phase was left behind years ago. The challenge now is different: containing an expansion that seems unstoppable and minimising its impact.