And how can we tell for sure if it's good or bad? Does killing these birds and mammals help maintain the ecosystem balance (due to these birds and mammals not killing billions other animals down the food chain, or not spreading infections and viruses), or the other way around?
A prerequisite for there to even be a chance of cats being involved in ecosystem balance would be for the cats to exist purely as part of the ecosystem, as in being exposed to negative feedback effects to it (e.g. starvation due to overhunting). As it stands, they are being fed by humans and mostly exist outside the ecosystem, and every kill by them only drains resources from the ecosystem.
I think the majority of pet cats live in cities and suburan settings, which are anyway highly artificial ecosystems. Also, as noted in another comment already, birds are fed in the same areas also, and provided nesting boxes, which probably increases numbers (or rather the carrying capacity) quite a bit. Studies seem to show that diversity has gone down, but biomass has even gone up a bit over 50 years [1]. The loss of species is apparently also related to removal of old buildings and modern ones lacking spaces to breed for birds like sparrows and swifts, and removal of landscape features that specialists depend on. Maybe cats play a role though.
The linked article says 90% of the mortality is caused by un-owned cats. I'd imagine that feral cats just replace wild cats in Europe, and thus do exist in the ecosystem with negative feedback (if they are not fed). Not sure about North America, as there is not really a small wild cat species I think?
On the other hand, humans have done a pretty good job of removing most of the other predators in the environment. Domestic cats must be replacing some of the natural predation that is no longer occurring.
Asking us to prove that cats killing wildlife is a bad thing.
A guy once told me that they remove the fallen logs from the Canadian forests because fallen trees are messy and ruin the forest. How do you even respond to such a stupid concept?
Not entirely, we should be worried about almost all of it but we shouldn't underestimate the reproduction rate of mice and rats that are quite successful in urban areas. If we were to remove all domestic cats we would almost immediately be overrun by hundreds of billions of them and they could quite literally end us. Mice population can double in 3 weeks. If you start with a few hundred million 30 weeks would turn into a few hundred billion and 60 weeks a few hundred trillion (2,4,8,16,32,64,128,256,512,1024) If they are currently killing 30B you might start with 15B mice rather than a few hundred million.
As a cat lover this only strengthens my opinion that they should stay inside the house, humans cause enough damage to the ecosystem without needlessly unleashing pretty efficient predators for no gain.
I would also say they would at least need to be neutered in that case so they dont reproduce with the feral population, but from a predatory perspective that would probably be fine then.
I would still not let our cats go out, my wife is pregnant so toxoplasmosis is very scary and bell or not we would be terrified of them getting lost or getting run over by a car or worse.
The human equivalent is poaching/hunting without a permit, which humans are not allowed. It's not like we can issue permits to cats and make them follow it.
Cats also routinely go into other peoples houses and either get themselves stuck or hunt rats/mice there, also something that humans generally are not allowed to do.
Istanbul has very few rats compared to other major global cities, largely because hundreds of thousands of community street cats keep the rodent population under strict control.
I love cats, and ours are indoor-only. They are happy, simulated, and in good health. I expect their life expectancy is longer than if they were outdoor cats.
They don't have the opportunity to kill birds or other animals.
On the other hand, cats reducing rodent populations sounds like a very good thing. If only we could get them to ignore species we want to keep around...
> a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually.
This is US only. I wonder what the numbers would be world wide.
The paper is about the species of "domestic cats", which includes feral cats, strays, etc, with unowned cats making up the majority of the kills as compared to owned cats/pets
This fact will be used by climate change deniers, when you point out the deaths caused by climate change: "Cats cause infinitely more death, we do nothing about it, can't do nothing about it, climate change may also cause death, but we can't do anything about. Do you want (us) to kill your cat just because it does some mischief?"
Cats are probably the ideal biological machines. Evolution keeps casting them in many form factors from the smallest (house cats) to the largest (bengal tigers?).
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.
I.e. cats might kill more birds and mammals than humans.
>I wonder also whether there's something about towns/cities that makes birds flourish, compared to other wild animals.
I would assume it has got do with the reason pigeons are sometimes called "flying rats", i.e. they can subsist on human trash, can survive in the environment and are not seen as negatively as rats and thus have less pest-control efforts pointed at them.
An extreme example would be Maos Great Leap Forward, where there was a human-led drive to exterminate sparrows as part of pest control, which in turn led to famines because sparrows also served as pest control for insects.
Humans are very good at introducing invasive species (domestic cat, kudzu) and pretty bad at forseeing the impact they have
I suppose I'm wondering that since domestic cats are already well introduced, perhaps removing them can also have unforeseen negative impacts to the environment!
They're counting cat-caused as anthropogenic i.e. part of anthropos-caused aka human-caused. And "single largest group" could be 1% if there are a lot of groups and each happens to be smaller than 1%.
I have read both the sentence and the abstract carefully, one of the other big antropogenic factors is "building colissions" which by itself is over one billion bird deaths.
And how can we tell for sure if it's good or bad? Does killing these birds and mammals help maintain the ecosystem balance (due to these birds and mammals not killing billions other animals down the food chain, or not spreading infections and viruses), or the other way around?
A prerequisite for there to even be a chance of cats being involved in ecosystem balance would be for the cats to exist purely as part of the ecosystem, as in being exposed to negative feedback effects to it (e.g. starvation due to overhunting). As it stands, they are being fed by humans and mostly exist outside the ecosystem, and every kill by them only drains resources from the ecosystem.
I think the majority of pet cats live in cities and suburan settings, which are anyway highly artificial ecosystems. Also, as noted in another comment already, birds are fed in the same areas also, and provided nesting boxes, which probably increases numbers (or rather the carrying capacity) quite a bit. Studies seem to show that diversity has gone down, but biomass has even gone up a bit over 50 years [1]. The loss of species is apparently also related to removal of old buildings and modern ones lacking spaces to breed for birds like sparrows and swifts, and removal of landscape features that specialists depend on. Maybe cats play a role though.
The linked article says 90% of the mortality is caused by un-owned cats. I'd imagine that feral cats just replace wild cats in Europe, and thus do exist in the ecosystem with negative feedback (if they are not fed). Not sure about North America, as there is not really a small wild cat species I think?
1 https://www.tandfonline.com/doi/full/10.1080/00063657.2021.1...
On the other hand, humans have done a pretty good job of removing most of the other predators in the environment. Domestic cats must be replacing some of the natural predation that is no longer occurring.
Not saying you are wrong, but we also feed birds and rodents, intentionally and by the by products of our society existing.
Sometimes I feel like people on this website act to be as obtuse and ignorant as possible to prove some kind of point. This is a great example
What a ridiculous gaslighting question.
Asking us to prove that cats killing wildlife is a bad thing.
A guy once told me that they remove the fallen logs from the Canadian forests because fallen trees are messy and ruin the forest. How do you even respond to such a stupid concept?
Not entirely, we should be worried about almost all of it but we shouldn't underestimate the reproduction rate of mice and rats that are quite successful in urban areas. If we were to remove all domestic cats we would almost immediately be overrun by hundreds of billions of them and they could quite literally end us. Mice population can double in 3 weeks. If you start with a few hundred million 30 weeks would turn into a few hundred billion and 60 weeks a few hundred trillion (2,4,8,16,32,64,128,256,512,1024) If they are currently killing 30B you might start with 15B mice rather than a few hundred million.
As a cat lover this only strengthens my opinion that they should stay inside the house, humans cause enough damage to the ecosystem without needlessly unleashing pretty efficient predators for no gain.
> Cats should stay inside they house
Isn't putting them on a leash, or having them wear a bell around their neck outside, enough for all parties?
Mhh, intriguing.
I would also say they would at least need to be neutered in that case so they dont reproduce with the feral population, but from a predatory perspective that would probably be fine then.
I would still not let our cats go out, my wife is pregnant so toxoplasmosis is very scary and bell or not we would be terrified of them getting lost or getting run over by a car or worse.
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by that logic, humans should stay inside too
The human equivalent is poaching/hunting without a permit, which humans are not allowed. It's not like we can issue permits to cats and make them follow it.
Cats also routinely go into other peoples houses and either get themselves stuck or hunt rats/mice there, also something that humans generally are not allowed to do.
Istanbul has very few rats compared to other major global cities, largely because hundreds of thousands of community street cats keep the rodent population under strict control.
I love cats, and ours are indoor-only. They are happy, simulated, and in good health. I expect their life expectancy is longer than if they were outdoor cats.
They don't have the opportunity to kill birds or other animals.
On the other hand, cats reducing rodent populations sounds like a very good thing. If only we could get them to ignore species we want to keep around...
> a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.3–4.0 billion birds and 6.3–22.3 billion mammals annually.
This is US only. I wonder what the numbers would be world wide.
And how many do wild cats kill? And how many would wild cats kill, if we allowed them to multiply as they want?
The paper is about the species of "domestic cats", which includes feral cats, strays, etc, with unowned cats making up the majority of the kills as compared to owned cats/pets
According to current US Admin, wind turbines kill most of the birds and must be banned. I'm not sure whom to believe.
I'm pretty sure who not to believe.
Felixer feral cat grooming traps:
* https://www.abc.net.au/news/2020-05-29/feral-cat-management-...
* https://thylation.com/products/
This fact will be used by climate change deniers, when you point out the deaths caused by climate change: "Cats cause infinitely more death, we do nothing about it, can't do nothing about it, climate change may also cause death, but we can't do anything about. Do you want (us) to kill your cat just because it does some mischief?"
Lovely murder machines.
Cats are probably the ideal biological machines. Evolution keeps casting them in many form factors from the smallest (house cats) to the largest (bengal tigers?).
Wait until you hear about humans.
From the abstract:
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.
I.e. cats might kill more birds and mammals than humans.
> cats might kill more birds and mammals than humans
Well yeah obviously. Cats kill relatively few humans, they're too little
Are they counting the loss due to human-induced reduction of biodiversity? E.g. wiping native land and replacing it with houses/cities/roads.
Humanity has a cost on nature, that should be mitigated.
Humans like domestic cats, which is one contributor to the overall human-induced reduction in biodiversity.
I wonder also whether there's something about towns/cities that makes birds flourish, compared to other wild animals.
>I wonder also whether there's something about towns/cities that makes birds flourish, compared to other wild animals.
I would assume it has got do with the reason pigeons are sometimes called "flying rats", i.e. they can subsist on human trash, can survive in the environment and are not seen as negatively as rats and thus have less pest-control efforts pointed at them.
If cats are killing wild animals that happen to flourish in human environments, is that such a loss to biodiversity?
(Genuine Q. I don't know anything about what biodiversity folk look for.)
An extreme example would be Maos Great Leap Forward, where there was a human-led drive to exterminate sparrows as part of pest control, which in turn led to famines because sparrows also served as pest control for insects.
Humans are very good at introducing invasive species (domestic cat, kudzu) and pretty bad at forseeing the impact they have
I suppose I'm wondering that since domestic cats are already well introduced, perhaps removing them can also have unforeseen negative impacts to the environment!
Read that sentence carefully.
They're counting cat-caused as anthropogenic i.e. part of anthropos-caused aka human-caused. And "single largest group" could be 1% if there are a lot of groups and each happens to be smaller than 1%.
I have read both the sentence and the abstract carefully, one of the other big antropogenic factors is "building colissions" which by itself is over one billion bird deaths.
Wait until they hear about bacteria and viruses
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