[lettergram]

Bob cats, mountain lions, etc used to have the entire US as their range. I suspect the bird population boomed after we got rid of the cats (100-150 years ago). Now that we have house cats they’re dropping again.

Boom-bust cycles for animals are common. I try to reflect what the natural order was 10,000 years ago and reflect. 20,000 years ago, there was an ice sheet over North America - ie no birds.

https://en.m.wikipedia.org/wiki/Laurentide_Ice_Sheet

[AlotOfReading]

Unless you're talking about the lynx (which mainly eats hares), the historic ranges of American cats barely overlap with LGM ice cover. It's not very relevant to this discussion.