Cats are hard wired to hunt. It isn't their fault. The fault lies with the owners. People in cities can reduce the problem by getting their cat fixed unless their goal is to sell kittens. Having an indoor/outdoor cat is a choice but I believe it is unhealthy as the cat will pick up all manor of infestation which then has to be countered with chemicals that are not safe for the cat or the humans despite what the packaging says. Many people do not even bathe their pets on a regular interval. Worse yet, people trim the claws of their pets which gives them zero ability to defend themselves. If the cat is not fixed it will most certainly have kittens and they are hard wired to do this in a place not near bigger mammals like humans so there is a high probability these kittens will become feral cats that will have kittens and the cycle repeats and thus the problem you describe is exacerbated.

This is less of an issue in rural areas that have natural predators for cats. Once in a blue moon I see a cat hunting my chipmunks. I feed horses, deer, chipmunks and about 20 species of birds. Even then it is rare to see a cat here as they are hunted by coyotes, large owls, eagles and mountain lions. I just had 3 giant eagles in my driveway eating a deer that didn't look both ways before crossing the highway. Feral cats do not last long with them around. For that reason alone people in rural areas should keep their cats indoors or avoid getting a cat. It is not fair to put domesticated animals in the mix with bigger predators.

If you’re in California know that feeding wildlife is illegal. And regardless of where you are it’s a bad idea as it habituates them to humans and attracting prey animals (like deer) will also attract their predators.

I left Cali, too many laws for me. The game warden here is quite happy that I and others feed the deer. It helps repopulate the wilderness behind my property. Bird lovers also appreciate that I feed all the birds. Nobody aside from me cares about the chipmunks. I am working towards unlocking the Crazy Chipmunk Dude title / achievement.

I am happy to attract the coyotes. It keeps them away from town and away from peoples children. My only gripe with them is when they are mating, they always choose 3am to do there little mating noises but that is only for a few weeks per year. They and the eagles clean up after the deer that get hit by cars i.e. the Circle of Life or nothing left to waste. I keep the coyotes, wolves and bears away from the house with vinegar.

All of that said, I am working on making things safer for the deer and the officials here appreciate it. By spring I should have enough fences and high voltage in place to corral them into a little sanctuary. Every year about 25 to 30 mule deer live in my yard and peek into my windows when they are hungry or their heated water buckets are empty.

I've got the opposite problem.

We have a food bowl in a room upstairs that gets a lot of indoor wildlife. (There were two times we had a river of ants moving through the room migrating from one place to another, then we never saw the ants again.)

Two months ago I saw a mouse climb into the cat bowl, grab a piece of kibble, then run into a whole between the floorboards and the wall. We have two housecats, one of which is highly aggressive to other cats, but despite numerous conversations (we show each other things all the time) I could not get the cats to recognize the opportunity here and had to use traps and institute a strict policy of putting the food back in storage when the cats were done feeding.

Keep in mind that many of the mammals killed by cats are mice and rats that we want to kill anyway.

I think a bell goes a long way, as already suggested.

Wild predators already have this job. By raising millions of cats in each countries, the pressure on wild rodents becomes huge. Without talking about wild birds whose populations are plummeting.

Mice and rats that live in urban and semi-urban areas are not really that more wild than cats. Their populations collapse if they lost access to their food sources which are provided by humans.

a bell?

It doesn't work, it even has the opposite effect: https://www.express.co.uk/news/nature/1617982/cat-news-resea...

The wording is not clear. I doubt that it has the 'opposite' effect. I think they mean that the ones with bells brought in the most catches with the suggestion being that the owners put bells on their cats because they bring a lot of catches in the first place, i.e. the best hunters get bells.

The opposite findings on the effect of bells: https://www.conservationevidence.com/actions/2332

Interesting. It works partially though. If we could stop the hunt completely that would be optimal because there are so many cats.

For a bit, I put a bell on my cat. He's a house cat, I just wanted to hear where about he was going through the house.

Within a few days he had figured out how to walk around the house without causing the bell to ring. The only time I'd hear it make a noise is if he had late night zoomies and go running up and down the stairs.

Another consideration - imagine having a phone around your neck that beeped fairly loudly at an annoying frequency each time you moved. Its really annoying and hurts their ears (their hearing being more sensitive).

Bells on collars don't solve the problem and make it worse for all animals involved.

1) How is cats killing animals such as birds and mice actually a problem? Do we have a shortage of birds or mice? For the most part, even if they're domesticated, I'd consider cats eating things as part of the natural food chain in the way that nature designed.

2) Suppose you could solve this "problem" and you could design a device that emits some sound and makes cats' hunting fail. Have you considered the far reaching environmental consequences of this? What are the second order effects on the insect populations and human crops?

A cat is a startup with VC money competing with a bootstrapped business.

Yes, wild birds and rodents are massively disappearing. The problem is there are too many domesticated cats hunting in the wild, to the point of exterminating wildlife. Insects are massively disappearing too. Not because of too many birds, because of too many pollutants in their environment. Scientists noticed the cat problem and I'm trying to find a solution on this website.

"Billions" of birds and mice isn't specific enough to care about. Cats are not even very good at hunting birds, being extremely specialized for hunting rodents - do you have any numbers that are not grotesquely extrapolated projections?

I wonder how such a joke questions sometime end up in the top of Ask HN.

While serious and relevant ones (like https://news.ycombinator.com/item?id=33693376 And others much better) drown with near zero attention.

It’s becoming worse over time, IMO.

It's an interesting problem.

Also, dogs can bark above 100dB which can disturb people hundred of meters away.

Our society should evaluate it's pets choices

It's a serious problem, wildlife is disappearing because of millions of cats: too many predators in the wild. If you develop a product that stop cats killing everything, people will probably buy it. You know, ecology and climate change are in the air at the moment. I'm asking here because people have products idea and know how to develop products.

My cat is leashed. She has the run of about 80’ of my back yard. She is a perfectly happy old cat, except during the winter when she finds it too cold to spend her entire day outside.

More importantly than preventing her from hunting wildlife, being leashed prevents her from shitting in anyone’s garden.

It seems BirdBeSafe products (https://www.birdsbesafe.com/)are really efficient to protect wild birds from cats. And cats look funny wearing them. Study results: https://www.birdsbesafe.com/pages/science-study-of-birdsbesa...