North Island brown kiwi
The North Island brown kiwi is a species of kiwi that is widespread in the northern two-thirds of the North Island of New Zealand and, with about 35,000 remaining, is the most common kiwi. It holds the world record for laying the largest eggs relative to its body size.
Females stand about 40 cm (16 in) high and weigh about 2.8 kg (6.2 lb) the males about 2.2 kg (4.9 lb). The plumage is streaky red-brown and spiky. It has a long and curved bill with the nostrils located near the tip. This unique adaptation helps the kiwi during foraging because it locates its prey by smell rather than by sight.
Northern brown kiwi are widespread throughout the North Island, occurring near Northland, Coromandel, Eastern North Island, Aroha Island, Little Barrier Island, Kawau Island, Ponui Island, and the Whanganui Region. These birds have adapted to live on scrub-like farmland, pine (an introduced tree) plantations, and their native forests, however, they still prefer dense, sub-tropical and temperate forests.
Northern brown kiwi are generally solitary and spend time with their mates only during the breeding season. They are very territorial and sometimes may even fight. These birds are nocturnal and during the day rest in their burrows. Kiwi usually have several burrows within each territory which they excavate themselves. Sometimes kiwi may shelter under hollow logs or in shallow holes hidden between tree roots. To communicate with each other they use grunts, hisses, and snorts. Their common call sounds as ‘kee-wee’; this is where the bird's name comes from.
Northern brown kiwi are carnivores. Their diet includes earthworms, beetles, snails, crayfish, insects, crayfish, amphibians, and eels. They will also sometimes eat fruits and berries.
Northern brown kiwi are monogamous and form pairs that can mate for life. They may produce 2-3 clutches a year. The nest is located in a burrow dug in the ground. The female lays 2 eggs and the male incubates them for 75-90 days. The chicks are precocial and hatch fully developed. They leave the nest within 1 week after hatching and are able to feed themselves. They usually become independent at 4 weeks of age and reach reproductive maturity when they are 4 years old.
The biggest threats to Northern brown kiwi are habitat loss and predation by mammalian predators such as dogs, cats, and stoat. 94% of chicks die before breeding in areas where mammalian pest control is not carried out. Nationwide studies show that on average only 5% of kiwi chicks survive to adulthood.
According to the IUCN Red List, the total Northern brown kiwi population size is around 26,550 individuals consisting of around 10,000-19,999 mature individuals. In 2015, a total population of 8,200 birds in Northland; 1,000 birds on Little Barrier; 1,700 birds on the Coromandel Peninsula; 7,150 birds in the eastern North Island and 7,500 birds in the western North Island. More than 1,000 individuals also occur on pest-free offshore islands, especially Hauturu-o-Toi/Little Barrier. According to the Kiwis for kiwi resource in 2015 this specie’s populations have been estimated in such areas: Northland - 8, 200 individuals; Coromandel - 1, 700 individuals; Eastern - Bay of Plenty, East Coast, Hawke’s Bay - 7, 150 individuals; Western - King Country, Taranaki, Whanganui - 7, 500 individuals. Overall, currently, Northern brown kiwi are classified as Vulnerable (VU) on the IUCN Red List but their numbers today are stable.
Northern brown kiwi are important predators of invertebrates in their ecosystem. They also consume berries and fruits and may help to disperse seeds.
