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What’s on the menu? For cats, just about everything.

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What’s on the menu? For cats, just about everything.

New research documents the vast and varied appetite domestic cats have for wildlife, including endangered species.
December 13, 2023

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Pet food companies might benefit from the idea that cats are picky eaters, satisfied only by that special can of tuna-flavored food. But Chris Lepczyk knows better.

Over the last two decades, the Auburn University ecologist has amassed a tally of all the different creatures domesticated cats have been documented eating. The number has passed 2,000 species and shows no signs of slowing.

“It sure seems there’s not a lot that a cat would pass up,” says Lepczyk.

Despite all the cute cat videos, it’s been long known Felis catus is a fierce killer, particularly when it comes to birds and small mammals. By one estimate domestic cats kill as many as 4 billion birds and 22.3 billion mammals per year in the United States alone.

But Lepczyk wanted to know just how broad these animals’ palates are. The findings could have implications for scientists and policymakers trying to understand how cats are contributing to changes in ecosystems or affecting the fates of endangered species.

 

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Cats have evolved to depend on animal protein. Their bodies aren’t built to metabolize plants, meaning they rely on meat to get most of their nutrition. Over the years, as Lepczyk went about his regular research, he kept a growing list of species turning up in any scientific papers that documented cat diets. The number has continued growing and growing. That, in itself, makes Lepczyk suspect the list will keep getting longer.

The menu is seemingly limitless: birds, rodents, snails, insects, frogs, salamanders, lizards. Small animals are the quary of choice—the average mass was around 45 grams, roughly the weight of eight U.S. quarters. But bigger creatures don’t get a pass, given cats’ willingness to scavenge from dead organisms. That includes emus, cows and yes, Homo sapiens. “That’s not a topic I want to touch,” says Lepczyk.

All told, it’s 2,036 species, he reported Tuesday in the journal Nature Communications. That adds up to 9% of all known birds, 6% of mammals and 4% of reptiles. Cats have been documented eating creatures on every continent, even Antarctica.

The most common meals were what you might expect, including animals most people are happy to see eaten—black and brown rats and house mice. But cats also have appetites for more rarified prey. They have dined on at least eight species that are now extinct, including six types of birds, a lizard and an Australian rodent with the distinctive common name of “white-footed rabbit-rat.” Another 347 threatened species tracked by the International Union for Conservation of Nature (IUCN) have passed through cats’ maws, ranging from green sea turtles to Newell’s shearwater, a small, rare seabird found only in Hawaii. One colleague sent Lepczyk a video of a cat eating a shearwater chick, then eating the adult bird when it returned to the nest.

For Lepczyk, the biggest surprise was how many types of insects are being devoured. Scientists have documented 119 species, although he suspects that number is too low, because insects can turn to indistinguishable mush in cat’s guts or feces, places where scientists look to discern dietary habits. “If there are invertebrates there and they can capture them, they will eat them,” he says.

One might think documenting all this carnage would turn an ecologist like Lepczyk into an avowed enemy of cats. But not so. As he spoke on Zoom from his home, his Siamese, Mochi, and orange tabby, Ahi, were loose somewhere with him. He knew they aren’t outside. They are strictly indoor cats, a nod to the toll they can take on wildlife. “Most of the scientists I know that work in conservation have cats,” he says. “This view that we hate cats is always surprising.”

Lepczyk hopes the new list will be useful for scientists, conservationists and others trying to gauge how cats might be affecting a species. Given his new research, it’s probably safe to assume that if a creature is small and cats are around, they are probably eating it.

Lepczyk, et. al. “A global synthesis and assessment of freeranging domestic cat diet.” Nature Communications. Dec. 12, 2023.

Photo: By Nataliia / Adobe Stock

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