Invasive snakes cause the extinction of unique reptiles of Gran Canaria in the areas where they spread.

An article by Julien C. Piquet and Marta López Darias.

We do not live in just any archipelago. The Canary Islands are not only known for being a great tourist destination that allows visitors to enjoy good weather and beaches practically all year round. What makes this archipelago truly unique is the nature it is home to, which is one of a kind in the world. Many ecosystems in the Canary Islands are unique to these islands, as are an extraordinary number of endemic species that are only found here. However, we inhabitants of the Canary Islands are generally unaware of their value, for if we knew and cared, we would be most proud of it and would demand a great commitment to protect it. And it is precisely due to the fact that what is not known is not valued, that the nature of the islands has suffered enormous destruction in recent decades, resulting in the extinction of exclusive species. Further exacerbating this problem is the continued releasing of exotic pets into the wild by some residents, thus posing another major threat to the islands' wildlife.

Such is the case of the California king snake, an invasive species on the island of Gran Canaria. It first appeared in the island's natural environment in 1998 and despite all efforts and resources allocated since 2009 by the Government of the Canary Islands and the Cabildo of Gran Canaria to control its spread, the species continues rapidly expanding and has even been detected on other islands of the archipelago. This invasive predator feeds mainly on endemic reptiles, as well as on introduced rodents such as mice and rats. However, only recently a team of scientists from the IPNA-CSIC has discovered that the snakes feed on these reptiles to the point of practically exterminating them from the natural environment of Gran Canaria. While the snakes practically wipe out the giant lizards of Gran Canaria in the areas they invade (99 % of the individuals disappear), Gran Canaria skink has decreased in number by more than 80 % and Boettger's gecko has reduced its population by a half.

Published in the prestigious international journal Proceedings of the Royal Society B: Biological Sciences, the results of this research clearly show that the ecological impact caused by this invasive snake is enormous and, unfortunately, irreversible if the invasion is not stopped. Moreover, the disappearance of these reptiles from the ecosystems of Gran Canaria is bound to lead to new problems. These three species have a fundamental ecological role in the nature of the islands since some of them, like the lizards, are key to the reproduction of plants, and all of them contribute to maintaining the demographic balance of invertebrates in the Canarian ecosystems. Once a species is no longer present in nature - as happens to an engine when it loses parts - the functions become maladjusted and everything starts to operate inadequately.

Researchers highlight the need to strengthen control measures against this invasion, particularly through innovative methods aimed at containing its expansion in Gran Canaria and controlling borders and the movement of species and goods within the archipelago to prevent the arrival of these snakes on other islands. They also appeal to Gran Canarian citizens to collaborate and encourage the Canarian society at large to help to comply with the regulations on invasive alien species in order to protect the unique ecosystems and species of the Canary Islands.