North Island brown kiwi (Apteryx mantelli)
|Size||Length: 40 cm (2)|
Male weight: 2.2 kg (3)
Female weight: 2.8 kg (3)
The North Island brown kiwi is classified as Endangered (EN) on the IUCN Red List (1).
The kiwi is New Zealand's national bird, and is a name often associated with inhabitants of these islands (4). The North Island brown kiwi (Apteryx mantelli) is one of five species of kiwi found in New Zealand (1). These birds have a spiky brown plumage, streaked with reddish brown (2). The long, thin bill is ivory and, uniquely for birds, has nostrils located at the end (2) (4). As flightless birds, kiwis may look quite bizarre as they lack visible wings (2); indeed, the genus name Apteryx means 'wingless' in Latin (5).
Endemic to New Zealand and previously widespread throughout the northern two-thirds of the North Island, this species has now declined in many districts (2).
Inhabits dense subtropical and temperate forests, and scrubland (2) (3).
Pairs can mate for life, although ‘divorces’ are not uncommon (3). During the breeding season, that runs from June to March, they are extremely territorial; males usually defend their territory through calling displays but may occasionally fight intruding birds (5). Females produce one of the proportionally largest eggs of any bird, comprising about 15 percent of her body weight (3) (5). The enormous egg is laid within the burrow. Two eggs may be laid in a clutch, but they are laid three to four weeks apart (3). Up to three different clutches can be laid in a year (5). The male North Island brown kiwi has the role of incubating the egg, and he develops a bare patch of skin on his belly (known as a 'brood patch') that facilitates the transfer of heat to the developing egg (5). Incubation takes 75 to 90 days (3) and the male will leave the egg to forage during the night, concealing the burrow entrance whilst he is gone (5). Chicks hatch fully-feathered and will venture out of the nest when about a week old, but they keep returning to the nest each day until they leave their natal territory at four to six weeks of age (3) (5).
Kiwis are nocturnal, terrestrial birds, spending the day in burrows dug into the ground with powerful claws (4) (5). Invertebrates constitute the majority of the diet, and insects are found by probing beneath leaf litter with the long beak (3) (6).
North Island brown kiwis have undergone a dramatic decline and as much as 90 percent of the population may have been lost since the start of the 20th Century (2). Research since the early 1990s has revealed that kiwi numbers in unmanaged areas of the North Island have been declining by about four percent a year (5). These birds evolved on an island that lacked terrestrial mammalian predators and have been devastated by the introduction of species such as dogs, stoats and cats (5); a single dog is known to have killed roughly 500 birds in one six-week period (2). Around 95 percent of chicks never reach sexual maturity, primarily as a result of predation, but also as the results of accidents such as falls from cliffs, drowning and encounters with traps or poison set for possums (3) (5). The loss of much of New Zealand's habitat has exacerbated these threats by isolating surviving populations and predators in fragmented pockets of remaining habitat (5).
The North Island brown kiwi is the subject of a concerted and wide-ranging conservation programme managed by the New Zealand Department of Conservation and Bank of New Zealand Save the Kiwi (3) (4). A number of different strategies are being employed, including the protection of wild nests and chicks by trapping predators, the artificial incubation of eggs and chicks in predator-free environments until they are big enough and old enough to cope with stoats and cats, and breeding of captive birds for release into the wild (3) (4). In the species' stronghold of Northland, the Whangarei Kiwi Sanctuary has been established whilst on the Coromandel Penninsula, Moehau Kiwi Sanctuary protects the individuals located there (5). Where there is active management of populations and predator control, North Island brown kiwi numbers have shown dramatic increases (5). It is hoped that the many conservation measures in place will help to preserve New Zealand's national bird for generations to come.
Find out more about the North Island brown kiwi:
Kiwis for Kiwi:
BirdLife International - Northern brown kiwi:
- Heather, B.D. and Robertson, H.A. (2005) The Field Guide to the Birds of New Zealand. Viking, Auckland.
BBC Wildlife Finder:
Authenticated (27/11/2006) by Dr. Hugh Robertson, Kiwi Co-ordinator (Research & Monitoring), Department of Conservation; and member of Bank of New Zealand Save the Kiwi.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Invertebrate: animals with no backbone.
- Natal: site of birth.
- Nocturnal: active at night.
- Territorial: an animal, a pair of animals or a colony that occupies and defends an area.
- Territory: area occupied and defended by an animal, a pair of animals or a colony.
IUCN Red List (June, 2008)
BirdLife International (April, 2003)
- Robertson, H. (2006) Pers. comm.
New Zealand Department of Conservation (June, 2008)
Bank of New Zealand Save the Kiwi (April, 2003)
TerraNature (June, 2008)