Yes, if you live somewhere with lots of birds. I grew up on a farm in country NSW, Australia. We almost always had dogs. A couple of cats visited for brief periods, and we'd constantly find dead birds on the verandah on their backs with the ribcage totally eaten out. So we never had cats for long, it wasn't really possible, unless you were to never let them outside.

Yes they do. I vacation in Costa Rica a few times a year (my parents have a house there so we stay at the same place) and there was a cat that wandered the area. She was an outdoor cat, but liked easy to obtain people food and/or cat food if people had it.

Every time I would go down there, she would kill birds, usually right near me. I could sit on the patio and I'd hear a scuffle and next thing I know there she is with a bird in her mouth. She'd present it to me by leaving it at my feet for a bit, then she'd pick it up and either play with it for a bit or just start eating it. She'd eat the thing whole: feathers, beak, bones and all. Sometimes this would happen multiple times in a week (and if we weren't around when she did it, she'd leave it out until we saw it, then eat it). I can only imagine how many she'd get when we weren't around.

My cat catches plenty of mice (and leaves them to me to tidy up, ugh), but no birds so far. We've got a bird feeder in the back yard as well.

Back in my parents' house we also had a cat, he'd catch a bird on occasion but it'd be our neighbour's pigeons that had just come back from a flight from France.

We woke up one morning to find the bloody remains of a white dove on the lawn. Then a couple of days later there was another dying dove in the middle of the road.

We put a bell on our cat after that - although at the moment she's only being allowed out in the mornings just in case someone with Covid pets her and she brings it in on her fur.

Cats have a fascinating territorial timeshare system. We have outdoor cams set up and there's steady cat traffic along the main garden path at all hours, often with one cat stalking another just out of sight - with occasional face-offs and mewling matches to claim a new slot.

Anecdotally, my cat has a balcony deck that he hangs out on from Apr-Nov, it’s about 4m off the ground. (no stairs or cat ladders down)

He has managed to kill two birds over a few summers. There are no bird feeders or anything a bird would want on the deck, cats are just very good at killing things.

The corvids like to hang out on the utility wires near the deck and yell at my cat, he doesn’t mind too much hehe.

Cats have instinctive behaviors to catch three kinds of prey: mice, birds and fish. However birds are a bit harder to catch than mice, and a well fed cat who didn't get to watch his mother hunting them may never become proficient. But proficient ones catch quite a few birds.

Source: my parents cat caught a lot of birds. Also I think Catchwatching by Desmond Morris.

> there will be traces such as a bunch of feathers and inedible parts

When my family lived in Hugo MN (north of St. Paul), we regularly saw feathers and other remains left by our cats. Occasionally they would leave a bird (or mouse) half dead on our kitchen floor... as an offering? Note that cats might not leave a lot of remains when they hunt, and the sometimes hide the parts they do leave.

Also, while our cats regularly hunted birds, the local blue jays liked to hunt our cats... for sport. The would send one bird out at one end of the yard as bait, and wait for the cat to start hunting it, creeping slowly towards the bird. Then another bird (or several) would suddenly dive bomb it from behind, dropping 20-25 feet strait into the cat's rear end. Our cat would end up launched (and/or leaping) 6+ feet in the air.

Your counter-argument to a scientific study is an anecdote? Not a very strong argument.

Animals must die all the time with minimal evidence left for humans to see. The lack of bodies is just indicates that the animal was rapidly consumed. Whenever I have seen dead birds outside they never last long.

My cats aren’t/weren’t subtle when they catch and eat prey. Neither are birds of prey or other vultures, when devouring another bird.

The cats I own and had over the past decades have gifted me hundreds of dead of half dead animals. Some of those cats were prolific killers.

I never witnessed a successful bird hunt, never received a bird as a gift. And most importantly: If there is any single animal which can easily leave traces of inedible stuff like feathers, down, beaks, claws — it’s birds. I never even have found traces of a killed bird, on the ground or in scat.

Despite this, I have no doubt cats kill a lot of birds. It’s just that a lone study with p<0.1 (rather than the classic p<0.05) is so far removed the reality I actually observe I can’t help but to have my doubts.

Mine does in Kent in the UK. I'd say he catches more mice and voles, but I'd say he gets a bird a week. Especially in the Spring when they are fledging.