That's not statistics, though? That's "we think there are fewer ownerless cats in the world than the authors do".
> We don't quarrel with the conclusion that the impact is big, but the numbers are informed guesswork.
Meanwhile the author outright says they're writing this opinion piece because they don't want to see cats banned as pets or people going out and killing a bunch of cats.
Cats kill 2.4b birds a year? Buildings kill 600m? These numbers are completely unbelievable. Were the made up in a left-wing think tank staffed entirely by birds?