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Comment by Ma8ee | Hacker News Reader

I know that cats eat a lot of birds, but I wonder how often cats really is the limiting factor of the population. Other things like scarcity of food or nesting places might often be more important.

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Armageddon

Domestic cats are killing an estimated 230M native Australian birds, reptiles and mammals every year

https://amp.theguardian.com/environment/2020/may/15/keep-pet...

The situation in australia is very different from other regions, in a previous discussion on HN we've already established that for central europe, domestic cats have a negligible effect on wildlife. (As in, orders of magnitudes below the next higher causes, which are mostly wild cats and pesticides).

> As in, orders of magnitudes below the next higher causes, which are mostly wild cats and pesticides

I'm not sure if you're aware, wild cats are a direct result of domestic cats.

This is backward, the domestic cat is a descendent of the Eurasian wildcats.

A substantial number of the wild cats in Europe are feral, but so what. Same cat, same niche, same place.

Perhaps they meant European wildcats[1], not feral cats. [1] https://en.wikipedia.org/wiki/European_wildcat

And how big part of the population is that? I can’t say if that is a big or a small number without knowing the total population.

And i'm sure mining for coal, building ever expanding suburbs or driving cars doesn't contribute to killing any bird or mammal.. I'd need the figures but i'm convinced that human activities are far more dangerous for other animals than the activities of our pets.

When you look at the numbers, it is very, very, hard to deny that free-ranging unowned cats are the largest limiting factor to the population. The size of the cat population causing a mortality swing of 24% in birds, is not some small number that might be masked by another closesly related statistic.

[0] https://www.nature.com/articles/ncomms2380

The number of cats in an area should be pretty closely related to the number of people living in the area. The more cats, the more people, and it would not be hard to believe that having more people in an area might lead to more environmental destruction and displaced habitats.

The control featured in the paper is Europe, where the domestic cat is younger and not as well adapted, environmentally, as that in America. There is significantly less environmental destruction, despite the controls featuring similar numbers of the animals. Simply having cities has not had a similar effect.

"I know we messed with the environment and the result has been devastating, but we should remember the environment is a harsh place and likely lots of stuff would have died even if we didn't meddle."

Cats in Australia kill a total of 377 MILLION birds per year[1] (99% of which are native species)

[1] https://www.nespthreatenedspecies.edu.au/publications-and-to...

I can’t really tell if that is a very high number or not without knowing the population of birds.

If 377 Million people were killed annually by something, would it make a difference what the population was?

It's a horrific number whether you've got a population of a billion or 10 billion.

Of course it would. About 43000 people die in car accidents in the US every year. That is apparently considered acceptable in a population of 332 million people. If the population was one million people, what would most likely be considered horrendous.

I admit that my standards regarding death of critters are somewhat different than death of people, but the total population do matter there too. 6 million deers are shot in the US every year in a population of 25 million. People don't seem to be very upset about that, but rather concerned that the population still is rising. Many people are very upset that any rhinos at all are killed.

And as the example with deers show, you can cull some populations quite heavily without any apparent ill effects.

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