The giant lizard of Gran Canaria, the Gran Canaria mullet and the lizard of the Pitiusas Islands (Ibiza, Formentera and numerous islets) are being wiped out by two other invasive reptiles. These are two snakes that landed on the Spanish islands about 25 years ago and have become relentless predators of species unique in the world. The situation has reached such a point that the International Union for Conservation of Nature (IUCN) today announced a new update to its Red List in which it raises the degree of threat of the giant lizard from least concern to critically endangered. ―four categories at a time― and the Gran Canaria lizard is in danger (without being critical), because they have lost 50% of the population since 2014. The Pitiusas lizard has decreased in the same proportion since 2010, and also passes from near threatened to endangered. The new version of the list, the world’s largest inventory of the conservation status of animals and plants, also places the Bornean elephant and the Chilean copypoa cactus at risk of extinction.
There are no native snakes on the Canary Islands. The first invasive snake to decimate island species is the California kingsnake (Lampropeltis californiae), native to the United States and northern Mexico, whose first specimen in the Spanish archipelago was captured in the wild in 1998 in the Gran Canaria municipality of Telde. The species arrived on the island as a pet, and from there it was introduced into nature, either intentionally or by escaping from a terrarium. The expansion continued and in 2007 it was considered established.
In the Balearic Islands the biggest threat is the horseshoe snake (Hemorrhois hippocrepis), which was introduced differently. This predator landed accidentally, traveling without anyone noticing among the root balls or trunks of large olive trees, highly prized for decorating gardens. In 2003 the first specimen was detected in Ibiza, which together with Formentera is the home of the lizard. Thus began a silent invasion that has led to the current disaster.
Elba Montes, member of biological invasions of the Herpetological Association, studied the expansion of the horseshoe snake and its relationship with the disappearance of lizards in Ibiza. Her conclusions, which she sent to the IUCN, indicate that by 2028 the snake could have colonized the entire Balearic island. “This means that on the same date the lizard would have become extinct, although there could still be some specimens left in certain areas,” she explains. City councils such as Santa Eularia del Río are creating refuges for the lizard in their urban centers that favor the habitat of the lizard.
![Lizard endemic to the Pitiusas Islands (Ibiza and Formentera) on which the horseshoe snake preys.](https://imagenes.elpais.com/resizer/v2/UDZJBTDN5ZDZNFVMJ6Y4JIK5IA.jpg?auth=9880924475e1b52a2eaa21fb16ae84176923855bd7843bd8b0fd107b2b67a751&width=414)
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The disappearance of this species “is not an anecdote, because it does not only mean that the symbol of these islands is gone, but that it produces a cascading effect as it is a key species: the snake arrives, there are local extinctions of lizards and the ecosystem changes,” explains Oriol Lapiedra, from the group that studies the adaptation of animals to global change at the CREAF research centre of the Autonomous University of Barcelona. “A very clear example is insects, if their main predator disappears, they increase, as we are already seeing,” he adds. Lizards are also pollinators and seed dispersers.
What is the solution?
“There is no magic way out,” answers Lapiedra. At this time, there is an invasion front, with very high abundances because there is a lot of food, but there will come a time when the horseshoe snake is found throughout the island and there is not so much food. “But it will also be too late for the lizard and we don’t want to get to that,” he says. In his opinion, a captive breeding plan should be implemented.
The first measure to address is to mitigate its devastating effect by eliminating those captured in control campaigns. But this does not solve the problem, at least for now, because snakes are very difficult to locate, they live most of the time underground. In Gran Canaria they are captured with search teams on the ground and also by installing traps. Their period of greatest activity is between March and July. Thus, 18,356 specimens of the California king snake have been caught since 2007, indicates the Government of the Canary Islands and the Cabildo of Gran Canaria in the Stopculebrareal.com project page. At first they were few, but the number has been growing. In 2023, 2,389 were captured and so far this year 1,533 have fallen. In Ibiza, 2,007 specimens of invasive snakes were caught last year (1,946 horseshoe snakes and 61 specimens of the also invasive ladder snake) and 889 in Formentera (888 specimens of ladder snake and one horseshoe snake). “The important thing is to prevent these situations, because in the end those who lose out are the animals that should not have arrived,” says researcher Montes.
![Horseshoe snake (Hemorrhois hippocrepis).](https://imagenes.elpais.com/resizer/v2/5JNAFQ7RTJBEXLRTCH2Z3D5ZXM.jpg?auth=6c30dfc87a7b5cf648c2008b740e3ac19fd3e073429e0368e5bb62b819bb40bd&width=414)
Eugenio Reyes of the Canarian federation Ben Magec of Ecologists in Action, considers that “special protection areas should be enabled for these species.” It must be taken into account, he adds, that “territorial planning has not helped the lizard either, for example, with the construction of shopping centers in the Tamaraceite area, on the outskirts of Las Palmas de Gran Canaria.”
Another species of lizard, however, the La Gomera giant (Gallotia bravoana), has improved its status from critically endangered to “just” endangered. The species has improved thanks to captive breeding and reintroduction programs. In this case, the reptile, “once common,” says the IUCN in a statement, was driven nearly to extinction by cats, rats and hunters. Now, feral cats continue to be its bane.
The elephant of Borneo and the cacti of Chile
This latest revision of the Red List places the Asian Bornean elephant at risk, following its first assessment as a distinct subspecies. An estimated 1,000 elephants remain in the wild due to habitat destruction from extensive logging of Borneo’s forests, agricultural plantations (particularly palm oil), the logging industry, mining and major infrastructure such as the Pan Borneo Highway. They also face poaching, accidental ingestion of agrochemicals, vehicle collisions and rapid expansion of human populations in Sabah means elephants are increasingly entering these areas in search of food, and may cause damage to crops and face retaliatory killings.
The IUCN also warns that 82% of copypoa cacti are at risk of extinction, up from 55% in 2013. Endemic to the Atacama Desert in Chile, the copypoa cactus craze in Europe and Asia has increased illegal trade, facilitated by social networks. The development of roads and housing in the area makes the plants more accessible to poachers and destroys their desert habitat. Climate change also threatens them, because the ocean fog they need to hydrate is affected by changes in temperature.
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