The Chatham Island Tomtit (Petroica macrocephala chathamensis) is a subspecies

Subspecies

Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 of Tomtit

Tomtit

The Tomtit, Petroica macrocephala, is a small passerine bird in the family Petroicidae, the Australian robins. It is endemic to the islands of New Zealand, ranging across the main islands as well as several of the outlying islands. It has several other English names as well. There are several...

 found on some of the smaller islands of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

.
It is most similar in plumage

Plumage

Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 to the South Island Tomtit, the nominate subspecies. The New Zealand government is implementing a plan to help this species and other bird species recover. The holotype

Holotype

A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...

 is in the collection of the Museum of New Zealand Te Papa Tongarewa

Museum of New Zealand Te Papa Tongarewa

The Museum of New Zealand Te Papa Tongarewa is the national museum and art gallery of New Zealand, located in Wellington. It is branded and commonly known as Te Papa and Our Place; "Te Papa Tongarewa" is broadly translatable as "the place of treasures of this land".The museum's principles...

.

Distribution

The Chatham Island Tomtit has been extinct on Chatham Island since the 1970s. This subspecies now has a population of about 1,000 birds and is currently restricted

Range (biology)

In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

 to the rat

Rat

Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

-free islands of Rangatira

South East Island/Rangatira

South East Island/Rangatira is the third largest island in the Chatham Islands chain, and covers an area of . It is located east of New Zealand's South Island...

, Mangere

Mangere Island

Mangere Island is part of the Chatham Islands archipelago, located east of New Zealand's South Island and has an area of . The island lies off the west coast of Pitt Island, south-east of the main settlement in the Chathams, Waitangi, on Chatham Island....

 and Pitt.