Yeah but we also overestimate that because when you trace all the references back you come to a dubious statistic formed from someone predisposed to the position.
Sure, anything you don’t like must come from biased sources.
It doesn’t trace back to a single statistic, multiple independent studies have looked into it. The often quoted 1 billion birds killed is actually below most scientific estimates of around 1.3 to 4 billion: https://www.nature.com/articles/ncomms2380
With domestic cats causing ~31% of the ~2.4 billion deaths and strays making up the majority. You can get similar numbers by ignoring domestic cats and simply look at the stray population and roughly estimate how much meat they need to survive and then compare the percentage of bids vs small mammals caught.
Besides just the fact that the American bobcat's range is all of the continental USA and it can outcompete the domestic cat in the wild for prey easily.
Sort of a natural limitation of science is that any "study" is treated as gospel truth by people not acquainted with the process or the mathematical knowledge required to verify.
Even low ends of the estimates for US stray cat population is 10x that. The majority of them need to hunt life prey to survive vs handouts, which is mostly small mammals but anyone that’s been around outdoor cats notices the birds are on the menu.
I’ll turn this around what percentage of a wild cats diet do you think are birds? 5% or 15%? You can work out the pounds of meat they need to survive a year and work back to number of birds needed.
Stray cats are distributed primarily in the urban population, not in the wild. They kill a bunch of pest birds which we'd otherwise use Ovocontrol or something similar to deal with.
That Nature study is pretty much all Fermi estimates. Since we're trading questions until you start answering, what is your estimate of house cats in the wild.
Fermi estimates are fine, we aren’t trying to track bird deaths out to 6 decimal places. I have no problem saying 30-70 million stray cats and something like ~6 billion calories per day from wildlife.
Stray cats may have higher density near people but so do song birds because humans feed birds they like to look at. Someone buying 10kg of bird feed a month keeps quite a lot of bird biomass alive.
Ah, but humans kill about 7 billion birds a day. So it's a drop in the bucket.
Or so one could reach with Fermi estimates. I think it should be made clear when you link that study that you meant "a back of the envelope calculation says that x birds were killed" etc. etc. rather than implying there was any rigor to it.
It doesn’t trace back to a single statistic, multiple independent studies have looked into it. The often quoted 1 billion birds killed is actually below most scientific estimates of around 1.3 to 4 billion: https://www.nature.com/articles/ncomms2380
With domestic cats causing ~31% of the ~2.4 billion deaths and strays making up the majority. You can get similar numbers by ignoring domestic cats and simply look at the stray population and roughly estimate how much meat they need to survive and then compare the percentage of bids vs small mammals caught.