[bjourne]

"We estimate that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals." https://www.nature.com/articles/ncomms2380

[amenhotep]

This is the first time I've seen the statistic quoted with the distinction that it's about feral cats, and it makes a heck of a lot more sense now than it did when I had the impression they were saying the cats I've had, which were on the whole utterly useless at catching things, were secretly massacring birds by the dozen. Thanks for the drive by enlightenment :)

[Tiktaalik]

It's an apples and oranges sort of issue here.

I have no doubt that stray and feral housecats in the cities and suburbs are killing great numbers of common house sparrows, but the things that are driving down numbers of endangered birds in rural and remote areas (where feral cats are not a problem) is habitat loss and the decline in food sources (ie. berries and bugs).

[tga_d]

Feral cats are extremely common in rural areas (though not in remote areas). Ask anyone who's lived on a farm or ranch about "barn cats".

Regardless, "the single greatest source of anthropogenic mortality for US birds and mammals" sounds unambiguously not great, even if they're mostly not endangered.

[orbital-decay]

How significant is that number? Is it large or small? How much of it is offset by larger populations of well-fed birds and rats in cities? In many countries, people specifically feed stray cats to keep cities rat-free, and predatory birds are often used for pest control (huge crow flocks terrorizing parks etc).