Not all introductions worked well. Rabbits were an unmitigated environmental disaster. Unchecked by any natural predator, they bred at a staggering rate and chewed their way across vast areas of pastureland as well as any garden that came their way. Attempts to control them by introducing ferrets, weasels and stoats did much more harm than good. Although these predators probably killed a reasonable number of rabbits, they also devastated populations of kiwi and raided the nests of flighted birds.