New Zealand Wren - Distribution and Habitat

Distribution and Habitat

The New Zealand wrens are endemic and restricted to the main islands of New Zealand and their offshore islands; they have not been found on any of the outer islands of New Zealand (such as the Chathams or the Kermadec Islands). Prior to the arrival of humans in New Zealand they had a widespread distribution across North, South and Stewart Island/Rakiura. The range of the Rifleman and Bush Wren included southern beech forest and podocarp-broadleaf forest, with the range of the Bush Wren also including coastal forest and scrub, particularly the Stewart Island subspecies. The New Zealand Rockwren is specialised for the alpine environment, in areas of low scrub and scree from 900 m up to 2,400 m. Contrary to its other common name (the South Island Wren) fossil evidence shows it was more widespread in the past and lived on North Island. The Stephens Island Wren was once thought to have been restricted to the tiny Stephens Island in the Cook Strait, but fossil evidence has shown the species was once widespread on both North and South Island. The Stout-legged Wren was similarly found on both islands, but fossils of the Long-billed Wren have only been found on South Island. Fossils of the Long-billed Wren are far less common than those of the other species, in fact its bones are the rarest fossil finds in New Zealand.

After the wave of extinctions and range contractions caused by the arrival of mammals in New Zealand the New Zealand wrens have a much reduced range. The New Zealand Rockwren is now restricted to South Island and is declining in numbers. The range of the Rifleman initially contracted with the felling of forests for agriculture but it has also expanded its range of habitats by moving into plantations of introduced exotic pines, principally the Monterey Pine. It also enters other human-modified habitat when it adjoins native forest.

Like all New Zealand passerines the New Zealand wrens are sedentary, and are not thought to undertake any migrations. It is not known if the extinct species migrated but it is considered highly unlikely as three of the extinct species were flightless. The situation with the Rock Wren is an ornithological mystery, as they are thought to live above the snow line where obtaining food during the winter would be extremely difficult. Searches have found no evidence that they move altitudinally during the winter, however they are also absent from their normal territories. It is suspected that they may enter a state of torpor (like the hummingbirds of the Americas or a number of Australian passerines) during at least part of the winter but this has not yet been proved.