Mammals such as rats and mice... which can carry many diseases including hantavirus, leptospirosis, lymphocytic choriomeningitis (LCMV), Tularemia and Salmonella...
Here's a question: suppose next year we mandate all cats are indoors unless they work on farms, and all cats allowed outdoors are sterilized. What happens to the small bird and mammal populations ten years later?
We are not separate from the evolutionary process and several species have effectively domesticated us in order to survive better. Our civilization has created new habitats and we don’t need to pretend that it doesn’t exist.
You want to help your local bird populations? Plant oak trees.
Oak trees serve as host to a particularly large number of species, many of them feed on the tree and serve as food for others year round along with acorns as food and species that feed on acorns as food. Oaks are keystone species as they have a particularly large positive impact on the local ecosystem.
Lots of birds eat mostly insects and only sometimes seeds, oak trees provide year round supplies of insects for birds to eat, in a wider variety and number than most other trees.
One of the reasons to worry about domestic cats in some areas of the British isles is not to protect birds and the like, but to protect the closely related extant cat species that is getting its genetics replaced too much with housecat genetics. This wild cat used to have very broad ranges which disappeared.
Islands with no cat species don’t have this consideration of course.
Bird populations in places that should have and used to have catlike predators are and should be fine for the most part. Predators tend to help the population dynamics and health of prey species. Some people are just really uncomfortable with predation.
https://www.science.org/doi/10.1126/science.aaw1313
The predation of cats is also unnaturally controlled as they are domesticated; people view them as pets primarily and thus prevent them from being killed (their predators are also heavily controlled - wolves, coyotes, etc). I don't see how you could compare that niche to previously extinct, naturally local species.
You might as well cut you comment at this point.