Acanthisittidae – New Zealand Wrens
The New Zealand wrens Acanthisittidae are a family of tiny passerines endemic to New Zealand. They were represented by six known species in four or five genera, although only two species survive in two genera today. They are understood to form a distinct lineage within the passerines. More recent studies suggest that they form a third (neither oscines or suboscines), most ancient, suborder Acanthisitti and have no living close relatives at all. They are called ‘wrens’ due to similarities in appearance and behaviour to the true wrens Troglodytidae.
New Zealand wrens are mostly insectivorous foragers of New Zealand’s forests, with one species, the New Zealand rockwren, being restricted to alpine areas. Both the remaining species are poor fliers and four of the five extinct species are known to (or are suspected of having) been flightless (based on observations of living birds and the size of their sterna); along with the long-legged bunting from the Canary Islands, they are the only passerines known to have lost the ability to fly. Of the species for which the plumage is known they are drab-coloured birds with brown-green plumage. They form monogamous pair bonds to raise their young laying their eggs in small nests in trees or amongst rocks. They are diurnal and like all New Zealand passerines, for the most part, are sedentary.
They, like many New Zealand birds, suffered several extinctions after the arrival of humans in New Zealand. Two species became extinct after the arrival of the Māori and the Polynesian rat, and are known today only from fossil remains; a third, the Stephens Island wren, became extinct on the main islands, surviving only as a relict population on Stephens Island in the Cook Strait. This species and the bush wren became extinct after the arrival of Europeans, with the bush wren surviving until 1972. Of the two remaining species, the rifleman is still common on both the North and the South Islands, while the New Zealand rockwren is restricted to the alpine areas of the South Island and is considered vulnerable.
Sometimes known as Xenicidae, this family has no more than three species (two if one assumes the Bush Wren is extinct); they are:
Rifleman Acanthisitta chloris
South Island Wren (Tuke, New Zealand Rockwren) Xenicus gilviventris
Number of bird species: 2