The South Island robin (Petroica australis), also known in Māori as the Kakaruwai., is a sparrow-sized bird found only in New Zealand, where it has the status of a protected endemic species. The birds are sparsely distributed through the South Island and Stewart Island/Rakiura, although the distribution is not continuous. The nominate, and the Stewart Island robin (P. australis rakiura) are the two subspecies. The species is closely related to the North Island robin (formerly P. australis longipes, now considered a distinct species), and also to the extremely rare black robin (P. traversi) of the Chatham Islands. Taxonomy The South Island robin has two subspecies: P. australis australis, the nominate form, and P. australis rakiura, the Stewart Island robin. These subspecies do not overlap in their distributions. The North Island robin (P. longipes), the tomtit (Petroica macrocephala), and the black robin (Petroica traversi) in the Chatham Islands are closely related species. P. traversi seems to be a Chatham Island derivative of P. australis, although the position of the most recent common ancestor has yet to be determined. The family Petroicidae of Australasian robins has a total of 49 species, mostly in Australia, New Zealand, and New Guinea. Fossil record There is molecular phylogenetic evidence to suggest two waves of immigration by the Petroica genus from Australia. P. longipes and P. australis can be traced to the first and P. macrocephala to the second wave. The evidence suggests that P. longipes and P. australis began to diverge prior to the Pleistocene era, and that the two South Island subspecies of P. australis began to diverge after the Pleistocene era. The separation time for the former was about three million years, and only 10,000 years (i.e., postglacial) for the latter. Fossils of New Zealand robins can sometimes be found near pit fall deposits, as they do most of their feeding/foraging on the ground. The fossil record also indicates the robins' presence throughout lowland New Zealand until drastic habitat reduction through deforestation by the Polynesian ancestors of the Māori and later European colonisers. Description The South Island robin is a small passerine, 10–18 cm in length and weighing around 35 g. North Island robins do resemble both females and juveniles of the South Island robins, as well as all the Stewart Island robins, which can sometimes make it difficult to distinguish between the three. The females and juveniles within a particular group of