Australia has a feral cat problem and lots of studies on how they decimate animal populations, including birds. https://www.publish.csiro.au/WR/fulltext/WR19174

Australia has a feral cat problem and lots of studies on how they decimate animal populations, including birds. https://www.publish.csiro.au/WR/fulltext/WR19174 https://www.publish.csiro.au/WR/fulltext/WR19174 for example, which cites lots of previous studies as well. "Introduced cats have had profound impacts on native faunas in many places, contributing to 26% of the total extinctions of mammals, birds and reptiles globally since 1600 (Doherty et al. 2016). The impacts of cats on native faunas have been greatest on islands, including large island nations such as Australia and New Zealand whose fauna evolved without exposure to felids"