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Comment by chkaloon | Hacker News Reader

Probably not many songbirds in Bern

I live in Switzerland. There are plenty of cats and plenty of birds as well.

I think this is because Swiss cities are fairly small and fairly green. There are plenty of places birds can go that are safe from cats and other predators and a forest is never far away.

Cats have been in Europe for thousands of years by now[1]. My guess is that birds have adapted. As others mention, I've only very rarely seen cats catching birds around here.

[1]not to mention the wild cats native to Europe, although of course in far smaller numbers.

  birds have adapted

Air-to-Ground cat-seeking missiles?

>> As others mention, I've only very rarely seen cats catching birds around here

That's exactly opposite of my experience - my mum has two cats that only live outside and I'd say that on average they bring at least 2-3 birds every week + 4-5 mice. Them hunting rodents is great, the birds not so much.

Traditional mitigation in my country is giving the cat a collar with a bell on it.

They learn to work around that.

Evidence suggests that most birds are incapable of learning the association between the bell and the cat.

In Europe, the danger for (song)birds are not cats, but rather glass front buildings, soil sealing (by roads and buildings), and in rural areas a drastic lack of biodiversity as farmland is ever more and more streamlined with no bushes or other patches of wild soil to provide space for wildlife.

In switzerland, large glass structures often have pictures of prey birds on them to discourage birds flying in to them.

Exactly! In the end it is the man who's the culprit. Birds and cats and coyotes (who occasionally eat cats) learnt to live together for millions of years.

Does your cat catch birds? I have had cat(s) for most of my life, currently two. They are proficient hunters, they can catch rodents and lizards and wasps, even a hare once. But never have any one of my current or previous cats caught a single bird.

I wonder, if the “common wisdom” of cats really catching and killing so many birds really is true?

https://www.npr.org/2020/04/18/820953617/the-killer-at-home-...

I know it is a scientific study published in Nature that the NPR article is based on. Cats kill birds, I have zero doubts, cats kill lots of birds, that’s likely. Cats kill as much as that estimate says, I have significant doubts. For multiple reasons:

Whenever a predator kills a bird there will be traces such as a bunch of feathers and inedible parts at the location of the kill and/or consumption. Never seen a single one of those.

It is a single estimate, never replicated.

There are hundreds of starlings, tits, and other small birds in my neighbourhood. It’s not like birds are a scarce resource. Nether do they seem especially held back by the local cats.

> 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.

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.

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.

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.

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.

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.

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.

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.

You can see varous survey of bird sightings at this website https://www.ornitho.ch/ . I am unforunately not a good ornithologist (or ornithologist at all) to know which species produce sound; however if you filter sightings in the last 15 days, then by canton (select "BE", which is the two letters code for Bern), then look for Bern (Bern is the name of a city but also of a canton, just as there's NY and NYC), then you will see there's at least 20 house sparrow in Bern city.

In light of the other comment about ample green space in Bern, and how songbirds have refuge because of it, we should consider whether cats killing songbirds is a more suburban phenomenon, and if so, why.

Given that both cats and songbirds have been around for much longer than suburban lifestyles, could the flatness of nothing-but-Kentucky-Bluegrass lawns be to blame?

Cats won't impact bird populations that much, nature balances itself well enough - assuming there's enough green areas where birds can nest, of course.

Plus, it helps control the mouse population as well.

If there are not, then it is likely for reasons other than the cat population.

Cats in the UK kill a lot of birds. But they are well, well behind habitat destruction as a cause for decline of bird populations.

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