Why cats have wiped out more species than any other predator

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According to a study, 2,084 different species have already been devoured by felines domesticated by man. Charming mascots or ruthless predators? Getty Images via BBC There are exotic species, such as the American crayfish, pike fish, cane toad, American bullfrog and raccoon, which tend to dominate statistics and reports on the impact of invasive animals on species extinction . But few invaders have caused as much damage to biodiversity as one of the most charming domestic pets: cats. Spanish domestic homes alone are home to around 4 million cats (one for every 12 inhabitants, on average). Of these, 120,000 end up abandoned on the streets every year. In Brazil, the proportion is even higher: one for every seven inhabitants, on average, or 27.1 million, according to the 2022 Pet IPB Census. Solitary predator and relentless hunter; agile, fast, voracious and with a strong territorial instinct. The cat is a cruel and untamed carnivore, but also captivating. He is an example of evolutionary perfection. All these characteristics make cats an extremely reluctant species to be domesticated, with a strong tendency towards freedom and disobedience. Largest vertebrate predator Cats have killed more vertebrates than any other predator. Their cosmopolitanism, their efficiency as a carnivorous animal and their enormous capacity for adaptation allowed them to colonize the entire world, from the sub-Antarctic islands to the hot and dry regions, close to the tropics. And their great fertility makes them a demographic bomb that is very difficult to deactivate. The fastest extinction of a species was caused by a cat. Tibbles was the mascot of the lighthouse keeper of Stephen Island, a small rocky ledge between New Zealand’s two main islands. There lived a strange flightless nocturnal bird resembling a lark. British ornithologist Lionel Walter Rothschild (1868–1937) described the bird in 1895 with the scientific name Xenicus lyalli — the Stephen’s Island Lark. A millionaire, Rothschild bought all known dissected specimens and dedicated the bird’s name to the island’s lighthouse keeper, D. Lyall. Preserved specimen of the Stephen’s Island Lark — Xenicus lyalli — at the Carnegie Museum in Pittsburgh, in the United States Wikimedia Commons via BBC In total, 13 specimens are known — the same ones that Tibbles the cat placed at his guardian’s feet. Passionate about ornithology, the lighthouse keeper dissected them before sending them to Rothschild. And since then, no new specimens have been found. Tibbles specialized in hunting this bird. He discovered them and, single-handedly, exterminated the species in the cold winter of 1895. With this, the Stephen’s Island lark and the dodo (Raphus cucullatus) began to share the undesirable honor of being extinct species before being described by science. . More than 1 million birds per year Very conservative calculations have led some authors to estimate that cats consume more than 1 million birds per year, on islands such as Kerguelen, in the southernmost reaches of the Indian Ocean. And it is known that, in just 75 years, cats made several species of reptiles disappear on small islands like Santa Luzia, in Cape Verde. There is also the case of the Canary Islands, which belong to Spain. It is estimated that the arrival of cats in the archipelago, 2 thousand years ago, is one of the causes of the disappearance of some birds, two giant rodents and the giant palm lizard. Even with their small stature and the countless memes of adorable kittens on social media, domestic cats (Felis catus) are killing machines, equipped with retractable claws, sharp fangs and night vision. Cats are perfect examples of animal evolution Getty Images via BBC These powerful predators can be anything but squeamish. They are always looking for prey to hunt or carrion to scavenge. And they eat whatever is available. Thanks to humans, cats have spread throughout the world in the last few thousand years. These ferocious felines were probably domesticated 10,000 years ago in the Middle East. Currently, they live on all continents except Antarctica. Cats were introduced to hundreds of islands and have become one of the most widely distributed species on the planet. Very varied diet The cosmopolitanism of cats has caused them to alter many of the ecosystems into which they were introduced. Cats transmit new diseases to many species, including humans. Its ecological impacts exceed those caused by native felines and other medium-sized predators. They threaten the genetic integrity of wild felines and feed on native fauna, having driven many species to extinction. For all these reasons, free-ranging cats (that is, domestic or wild cats with access to their external environment) form one of the most problematic invasive species in the world. A meta-analysis of 530 articles, books and scientific reports published over more than a century resulted in the first complete record of the animals that are commonly devoured by domestic cats. The list of victims is long: 2,084 different species. The majority of them are birds (981 species), followed by reptiles (463), mammals (431), insects (119), amphibians (57) and other taxonomic groups (33). The most common prey are rats, mice, sparrows and rabbits, but there are also records of cats hunting surprising prey, such as Galapagos tortoises, Australian rheas and even domestic cattle. Some of the creatures mentioned on the list — including humans — are too large for cats to hunt. But they reflect the scavenging tendencies of felines. Almost 350 of these species appear on several red lists of species at risk of extinction. And many of them are already extinct. Many are small birds, mammals and reptiles endemic to islands that do not have natural predators such as felines. This means that unsuspecting prey do not have defensive reactions. Eleven of the recorded species, including the Hawaiian crow (Corvus hawaiiensis), the New Zealand quail (Coturnix novaezelandiae) and the white-footed rabbit rat (Conilurus albipes) of Australia, are considered extinct . Insect Eaters The data in the article is conservative. The records are a representation of the species that serve as food for cats, but felines eat much more than we can identify. Insects, for example, only represent just under 6% of the species eaten by cats. But this number is probably an underestimate, due to the difficulty of identifying insect remains in feline stomachs and excrement, compared to vertebrate feathers or bones. Insects represent just under 6% of the species devoured by cats Getty Images via BBC Furthermore, the number of prey increases proportionally to the amount of scientific publications. And, as most of the sources used for the meta-analysis come from Australia and North America, it is likely that this geographic bias hides the entirety of the species consumed. After all, animals native to these continents dominated the data set. Future research will certainly help to understand the impact of cats in other regions that have extraordinary biodiversity, such as South America, Asia and Africa. Numerous creatures at risk of extinction will then be discovered and end up in cat litter boxes. But the truth is that blaming felines ends up creating a scapegoat for a much bigger problem, which involves our own ecological commitment. If we, humans, cannot change our behavior to protect biodiversity, why should we expect this same awareness from cats? *Manuel Peinado Lorca is professor emeritus and director of the Royal Botanical Garden of the University of Alcalá, in Spain. This article was originally published on the academic news website The Conversation and is republished under a Creative Commons license. Read the original Spanish version here.

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