Ibiza is no stranger to exotic creatures, but one invader is making waves—literally. The horseshoe whip snake (Hemorrhois hippocrepis), originally from mainland Spain and North Africa, has not only established itself across the island but has now been spotted swimming in the sea.
Once thought to be purely land-dwelling, these reptiles are proving scientists wrong by making their way to Ibiza’s offshore islets, threatening one of the island’s most iconic creatures: the endemic Ibiza wall lizard (Podarcis pityusensis).
How did we get here? And what does this mean for Ibiza’s delicate ecosystem?
The unstoppable spread: how the snakes got here
The horseshoe whip snake first arrived in Ibiza in the early 2000s, hidden in the roots of ornamental olive trees imported from the mainland. With no natural predators on the island and a plentiful food supply—including the small but ecologically vital Ibiza wall lizard—these serpents quickly thrived.
What started as a few isolated sightings has now turned into an island-wide invasion. And just when conservationists thought they had a handle on the situation, the snakes took it a step further: they started swimming.
“Seeing them in the sea was a shock. We never expected them to become such skilled swimmers”, says Víctor Colomar, coordinator of COFIB (Consortium for the Protection of Wildlife in the Balearic Islands).
Today, these ophidians are making their way to small islets around Ibiza, colonising places that were once safe refuges for the wall lizard. From the rocky islets off Portinatx to s’Espartar in the west, the invasion is expanding.
Super-sized specimens: the Ibiza ‘Gigantism’ phenomenon
As if their ability to swim wasn’t enough, Ibiza’s snakes are also getting bigger. And not just a little bigger—record-breaking bigger.
In 2013, conservationists captured a 1.83-metre-long horseshoe whip snake in the island, the largest ever recorded for this species. The average size for these specimens is around 89 cm, but some in Ibiza are almost double that length.
What’s causing this ‘gigantism‘? Scientists believe the lack of predators and an abundance of prey allow them to grow unchecked. And bigger snakes mean more eggs—and more eggs mean even more snakes.
The Ibiza wall lizard: a species in peril
For thousands of years, the Ibiza wall lizard has been a symbol of the island, its bright green and blue scales blending into the island’s rugged terrain. But the arrival of the snakes has changed everything.
On some islets, like S’Ora, the lizards have already been wiped out. The last known sighting of a lizard there was in 2017.
Experts warn that if the invasion continues at its current pace, the wall lizard could disappear entirely from Ibiza by 2030.
“This is an ecological disaster“, warns Jaume Estarellas, a biologist studying the impact of invasive species in the Balearics.
What’s being done to stop the snake invasion?
Conservationists are in a race against time to control the spread of these invaders. Some of the main efforts include:
- Snake traps – In 2024 alone, the IbizaPreservation foundation placed 280 traps across the island, capturing nearly 500 snakes in an attempt to slow their spread.
- COFIB Control Programme – Every year, COFIB captures over 3,000 snakes across Mallorca, Ibiza, and Formentera.
- Private landowner involvement – More property owners are working with conservation groups to set up traps on their land.
But despite these efforts, experts admit the battle is far from over.
“The truth is, we underestimated these snakes”, says Estarellas. “We’re dealing with an incredibly adaptable predator”.
A future at risk: can Ibiza win this fight?
As more snakes take to the sea and reach new territories, Ibiza’s ecosystem faces an uncertain future. While conservation efforts are helping, the snakes continue to spread.
Could stricter regulations on imported trees help prevent new invasions? Should a larger-scale removal programme be launched?
One thing is certain—without urgent action, one of Ibiza’s most beloved species could vanish forever.
How can you help?
If you live in Ibiza or visit regularly, you can contribute to conservation efforts:
- Report snake sightings to COFIB.
- Avoid importing plants with soil from outside the Balearics.
- Support local conservation projects like IbizaPreservation.
The battle between Ibiza’s ancient wildlife and this modern invader is unfolding right now. Will we act in time?
