For decades Ibiza was known as the island of paradisiacal beaches, spectacular sunsets and nightlife. However, there was another peculiarity that set it apart from many other Mediterranean destinations: the almost total absence of snakes.
Today the situation is completely different.
In recent years, social media have spread images and videos of snakes spotted along paths, in the countryside and even in the sea in Ibiza. Some specimens have been filmed swimming near beaches or crossing stretches of sea to reach small islets in the Balearic Islands.
But what is really going on in Ibiza? Where are these reptiles coming from? Are they dangerous to tourists? And how many of these snakes are on the island today?
Colubro Ferro di Cavallo: the snake that invaded Ibiza and the Balearic Islands
Who is the star snake? The Horseshoe Coluber (Hemorrhois hippocrepis) accidentally arrived in Ibiza in the early 2000s, hidden in the roots of ornamental olive trees imported from the Iberian Peninsula.
How big are they? In Ibiza, these snakes grow extraordinarily large: they can exceed 2 meters in length, weighing two and a half times as much as peninsular specimens, which rarely exceed 1.8 meters. Some specimens have been found as thick as an adult’s wrist.
Are Ibiza Horseshoe Colubro snakes dangerous to humans? No – this is a non-poisonous species and completely harmless to people. The real danger concerns the local ecosystem, with several endemic species increasingly at risk.
An island that had no snakes for centuries
For much of its history Ibiza has been virtually snake-free.
Geographic isolation has allowed the development of a unique ecosystem, characterized by the presence of the Pitiuse lizard (Podarcis pityusensis), an endemic species that lives only in Ibiza, Formentera and the small surrounding islets. For thousands of years this reptile has thrived without any particular natural predators.
The ecological balance of the island remained virtually unchanged until the early 2000s, when a seemingly innocuous event changed the fate of the local fauna forever.
When did the snakes arrive in Ibiza?
Scholars place the arrival of the first snakes between 2003 and 2004.
In those years numerous ancient olive trees were imported from mainland Spain to furnish villas, resorts and private gardens during the island’s building boom. Hidden in the hollows of the trunks and among the roots also traveled unknowingly some snakes.
The first official sightings date from that very period and initially caused no particular concern. The reptiles appeared confined to a few limited areas, and no one imagined that within two decades they would become a major environmental problem in the Balearic Islands.
What species of snakes have arrived on the Balearic island?
Contrary to what one might think, no single species is present.
Accidental introductions have brought several snakes to Ibiza from the Iberian Peninsula, including:
- the horseshoe coluber (Hemorrhois hippocrepis);
- the scale coluber (Zamenis scalaris);
- Montpellier’s coluber (Malpolon monspessulanus).
Among these species, the horseshoe culvert is the one that has adapted best to the local environment and now accounts for most sightings.
The horseshoe coluber is a snake native to southern Spain, Portugal and North Africa.
It gets its name from a characteristic dark horseshoe-shaped spot present behind the head. Adults can exceed five feet in length and, in some cases, reach sizes close to two feet.
It is a snake:
- non-poisonous;
- very fast;
- excellent climber;
- excellent swimmer;
- Active mainly during the day.
It is not considered dangerous to humans and generally tends to flee when it feels threatened.
Why has Ibiza’s snake population grown so rapidly?
Once the snakes arrived in Ibiza, they found nearly ideal conditions.
The island was rich in prey and virtually devoid of natural predators capable of containing its spread. In addition, the mild climate of the Balearic Islands favors the survival of young specimens.
Each female may lay several eggs each year, and over time the population has begun to expand at an increasingly rapid rate.
Beginning in 2010, residents began to report a decrease in lizards and a steady increase in snake sightings in areas farther and farther away from where they were initially observed.
How many snakes are there in Ibiza today?
Determining the exact number is impossible.
However, data collected by environmental agencies clearly show the extent of the phenomenon. Thousands have been captured in recent years through monitoring and containment programs.
According to some estimates, the horseshoe coluber would now occupy much of Ibiza’s territory, with a presence that could affect about 90 percent of the island.
Despite capture campaigns, the population continues to be large and widespread.
Do Colubro snakes really swim in the sea between Ibiza the Balearic Islands?
Yes.
And that is probably the most surprising aspect of the whole affair.
Numerous documented sightings show specimens swimming in the open sea. Scholars have recorded several cases of snakes observed hundreds of meters from the coast.
This behavior allows them to reach small islets that until a few years ago were safe havens for local wildlife.
The ability to cross the sea is one reason why its expansion is particularly difficult to stop.
The truth about snakes swimming in Ibiza: they are not sea snakes
One of the most common misconceptions concerns the nature of the snakes spotted in the waters of Ibiza. In fact, many tourists, seeing videos posted on social networks, think they are facing sea snakes similar to those living in tropical oceans.
In reality, this is not the case.
The reptiles that are colonizing Ibiza are terrestrial snakes. They normally live in the countryside, between dry stone walls, in rocky areas, and in wooded areas of the island.
Their special feature is another: they are excellent swimmers.
Scholars have documented several cases of specimens capable of crossing stretches of open sea to reach small nearby islets, contributing to the spread of the species in the archipelago.
True sea snakes belong to different zoological groups and live mainly in the tropical waters of the Indo-Pacific. There are no natural populations of sea snakes in the Mediterranean Sea.
For this reason, although it may happen to spot a snake while swimming near the coast, it is not a marine species or a particularly dangerous animal for swimmers.
Can they go all the way to the beaches?
Yes, it can happen.
In recent years, some bathers have reported the presence of snakes near the shore or near small boats. However, these are sporadic incidents that attract great media attention precisely because they are unusual.
The horseshoe coluber does not seek contact with humans and in most cases tends to move away quickly when it senses a human presence.
Do tourists really take risks?
The short answer is no.
Despite the striking images circulating online, the snakes found in Ibiza are not considered dangerous to humans. They are not venomous sea snakes or aggressive species.
Encounters with tourists are generally harmless, and millions of people continue to visit the island each year without any problems related to their presence.
As impressive as it may be to observe a snake swimming in the crystal-clear waters of Ibiza, the phenomenon is primarily an environmental issue and not a real threat to tourism.
The real victim: the iconic lizard of Ibiza
The main consequence of the invasion affects local biodiversity.
Pitiuse lizards form an important part of the horseshoe snake’s diet. In many areas of the island where snakes have long been established, lizard presence has declined dramatically.
Some local populations have even disappeared, prompting experts to sound the alarm about the conservation of one of the archipelago’s iconic species.
Can Ibiza authorities stop the snake invasion?
In recent years, the Balearic Islands has initiated numerous monitoring and trapping campaigns.
Thousands of traps are set each year to contain the spread of snakes and protect the most nature-sensitive areas.
However, experts believe that complete eradication is now very difficult. The main goal is to limit population growth and safeguard the last areas where the endemic lizard can still survive.
Is Ibiza still worth visiting?
Absolutely.
The presence of snakes is a serious ecological problem, but not a real threat to those who choose to vacation on the island.
Spectacular beaches, hidden coves, crystal-clear waters, unforgettable sunsets and a lively atmosphere continue to make Ibiza one of the Mediterranean’s most beloved destinations.
Do you love sea travel among Mediterranean islands? Also read our article on Tenerife, the island of eternal spring!
The story of the Ibiza snakes is not that of a dangerous island, but that of a fragile ecosystem that is dealing with the consequences of an accidental introduction that occurred just over two decades ago. It is a reminder of how delicate the natural balance of islands can be and how easily it can be altered by human intervention.
