I'm always surprised that cats are able to dominate ecosystems like this. You'd think a local apex predator would have filled that niche and been better adapted to the environment.
Australia's birds never had a local predator like the cat. They just had to keep an eye on the sky for birds of prey and maybe snakes.
It seems that efficient hunters are quite rare to evolve, as there have been lots of ecosystems totally turned on their head with the arrival of a new predator. Stoats, foxes, house cats have all found niches in ecosystems unfilled for hundreds of thousands of years and wiped out many local species. Or maybe the problem is that they are too good, and if left to themselves they would decimate their prey to the point they can't sustain their own numbers and die out; in the long term predators need to exist in an equilibrium.
Owls aren't as prolific though if pest control is your goal. A cat will happily kill a dozen mice and eat exactly one. They are adorable murder-machines.
Marsupial lions were believed to fill this gap in the food chain. Unfortunately, they died out 60,000 years ago. Now cats and foxes are hunting native species, some faster than is sustainable. Eventually an equilibrium will be found, where the wild cat and fox populations can’t be sustained due to over-hunting, but it will likely come at the cost of many native species disappearing.
