Outside cat / feral cats have had massive negative impacts on bird and small mammal populations. Particularly in areas where they fill an ecological niche that the wildlife hasn't adapted to due to none of the local fauna being in that niche. Hawaii and Australia in particular have this problem.

[–] MoodyRaincloud@feddit.nl -3 points 1 year ago

Those are indeed special situations where cats are basically an invasive species.

Here in Europe the correlation between cats and bird population is not so strong. While destruction of habitat and the crash in insect numbers are the big culprits.