It's not that simple though, it's also about: does predator A hunt at times and in areas when/where prey 1 lives/acts? If not, then you get a Hawaiian Rats vs.

It's not that simple though, it's also about: does predator A hunt at times and in areas when/where prey 1 lives/acts? If not, then you get a Hawaiian Rats vs. Mongeese scenario. Like so many invasive species that now run amuck on islands around the world, mongooses were intentionally introduced to Hawaii. Sugar cane farmers took their cue from Jamaican plantation owners who imported mongooses to control rat populations. In 1883 the mongooses were let loose in the fields, an approach that proved to be colossally uninformed. As it turns out, rats are nocturnal and mongooses are diurnal. The exotic predators never came in contact with their rodent prey, and native bird populations began crashing instead. https://green.blogs.nytimes.com/2012/06/11/an-invader-advances-in-hawaii/ https://green.blogs.nytimes.com/2012/06/11/an-invader-advanc... In addition Australia doesn't have many large predators that weren't introduced, except for reptiles. The most impressive of those, the saltwater crocodile, isn't exactly suited to hunt anything far from shore.