Adorable pets by day, relentless predators by night

Cats are beautiful, elegant, mysterious. “And my hand intoxicates itself with the pleasure / of touching your electric body,” wrote the poet Charles Baudelaire about his cat, Tibère. For about 10,000 years we have lived with these felines more or less harmoniously. But recently scientists have been demonstrating that their large proliferation is seriously affecting biodiversity, as shown by a pioneering study carried out in Sant Cugat del Vallès.

Domestic cats have a very strong predatory instinct, and they hunt actively even when well-fed. It has always been said that they hunt mice, but in fact they capture all sorts of small animals, such as shrews, voles, rabbits, bats, lizards, newts, toads, frogs... and a multitude of little birds like sparrows, tits, robins, and a long etcetera.

If we add to this predatory instinct its high current density, the problem is guaranteed. Within three municipalities of Vall d’Aro there are about 2,850 domestic cats in 106 km², with a density of 27 cats/km², according to Josep Maria Bas, a researcher at the University of Girona. The wild cat (Felis silvestris), which is the closest species with which we can compare the domestic cat (Felis catus), presents in Europe an average density of 0.8 individuals/km², “34 times lower”, points out Bas. We can speculate that, if humans did not exist, instead of 2,850 domestic cats in this area, there would be 85 wild cats, which is the number of this type of predator that the ecosystem can naturally sustain. 

In Sant Cugat, where there is a minimum of 2,422 cats spread across 252 colonies, the impact of domestic cats on a wild species, the Iberian-Provençal lizard ("They decimate lizards

In Sant Cugat, where there is a minimum of 2,422 cats distributed in 252 colonies, the impact of domestic cats on a wild species, the Iberian-Provençal lizard (Podarcis liolepis), has been quantified for the first time. The study has found that there is an inversely proportional relationship between the abundance of cats and that of these reptiles, to the point that where there are many cats, the lizards disappear completely. None remain. It is also observed that Tarentola mauritanica): "Geckos eat moths, such as those of the pine processionary caterpillar. If there are fewer geckos due to cats, the populations of processionary caterpillars skyrocket.

However, the problem has a global scope. In the United States, domestic cats kill between 1.3 and 4 billion birds and between 6.3 and 22 billion mammals each year, according to a 2013 study by the Smithsonian Conservation Biology Institute, and are the leading cause of anthropogenic mortality. In fact, they are considered responsible for 14% of global extinctions of mammals, birds, and reptiles.

This leads to paradoxical situations such as the one that occurs in

This leads to paradoxical situations like the one occurring in the Muntanyans of Torredembarra, where a population of the endangered red-tailed lizard (Acanthodactylus erythrurus) lives, which is preyed upon by domestic cats settled in the area. Therefore, "public money is used to protect both the lizards and the cats that kill them," according to Ortega, who denounces that the animal welfare law was "designed according to the criteria of a minority sector of society and behind the backs of the scientific community and local administrations".  Scientists believe that it should all be managed differently. For example, by reducing the food supply to let natural selection act and the colonies shrink. And disappear. Right now, in the Vall d'Aro, only 50% of the cats in the colonies are sterilized. In this context, "you cannot feed without limits," states Bas, who recalls that "to bring down the predator, there is no better way than to reduce the food resource."Right now it is not an easy issue to manage, but not because of the felines. As Josep Maria Bas says, it is all “not a problem of cats but a problem of people”.