Captain James Cook and later whalers and sealers introduced cats (Felis catus), but these did not become common until the 1830s. In the 1870s, rabbit numbers were driving farmers from their land, so quantities of cats were released to control them.

Rat-catchers
Cats were carried on ships to control rats. When James Cook’s Resolution was tied to trees in Dusky Sound, Fiordland, in 1773, one of the cats ‘regularly took a walk in the woods every morning and made great havoc among the little birds, that were not aware of such an insidious enemy.’
The cats went into the bush, joining rats and stoats as predators. Soon after cats appeared on Little Barrier, Cuvier and Stephens islands, saddlebacks and other native birds disappeared. Introduced to forest-covered Herekopare Island, cats quickly extinguished parakeets, robins, fernbirds, brown creepers, snipe and a native bat.
Wild cats live high in the mountains and along the coast, as well as in bush, scrub, and on farmland. They feed mainly on young rabbits, rats and mice, but also on native birds, lizards and large insects such as wētā, cicadas and dragonflies. In mainland bush, birds make up some 15% of their diet but, with most native birds gone, they usually eat blackbirds, chaffinches, silvereyes and hedge sparrows.