Rats eat a wide range of animal and plants including invertebrates, lizards, birds (adults, chicks and eggs), bats, flowers, fruits, stems and leaves. Rats directly eat or compete with native wildlife.
Rats have caused the extinction of several New Zealand bird species and are the major cause of decline for many other species, including reptiles and invertebrates. Rat predation was the cause of the extinction of the Stewart Island snipe, Stead's bush wren and the New Zealand greater short-tailed bat. Rats can breed throughout the year if conditions are suitable, with a female producing up to five litters a year.
There are three rat species present on Rakiura: the kiore / Pacific rats, Norway rats and Ship rats, all of which were human-introduced. There is variation in presence between the different rat species; Norway and Ship rats have been found in all vegetation types of Rakiura. Pacific rats / kiore were found to be dominating in manuka shrubland. More research is needed to understand this variation and the interaction between the rats and other predators.
Mice arrive on Rakiura but are not established.