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Apteryx mantelli
Kiwi are endemic to New Zealand
Kiwi are one of the world’s most unusual birds and no Kiwi species are found anywhere else. Kiwi are the smallest of the ratite family of birds that include Moa, Ostrich, Emu, Rhea and Cassowary.
Kiwi are divided into five species
The five identified species of Kiwi and their distribution are;
- Great Spotted Kiwi – Apteryx haastii – North-western South Island and Arthur’s Pass
- Little Spotted Kiwi – Apteryx owenii – Several offshore islands and two mainland sanctuaries
- North Island Brown Kiwi – Apteryx mantelli – Four regions in the North Island
- Rowi – Apteryx rowi – Okarito on the West Coast of the South Island
- Tokoeka – Apteryx australis – Fiordland and Haast Range and Stewart Island
The North Island Brown Kiwi is further split into varieties, named after where they are found;
- Northland Brown,
- Coromandel Brown,
- Western Brown,
- Eastern Brown.
The varieties are thought to have occurred due to the population becoming isolated from each other and no longer interbreeding.
Kiwi In the Tangihua Forest
At one time, North Island Brown Kiwi would have been abundant in Northlands Tangihua Forest, but they are now functionally extinct. Functionally extinct means that although Kiwi may be present, they are no longer able to raise their young, so they are the last generation of Kiwi to live in the forest.
Adult Kiwi are large enough and strong enough to protect themselves from cats, rats, stouts and ferrets, but that is not true of the chicks and juveniles who are killed by these predators before they are old enough to breed.
Kiwis Physical Description
Size and Shape
Kiwi have a coned shaped body, ending in a strong neck, small head and long, slightly curved beak. They have no external tail and their wings are small, almost non-existent, and end in a claw. Instead of powerful wings Kiwi have powerful, muscular legs. These legs account for a third of the Kiwi’s body weight and are used for running, burrowing and fighting, either with predators or other Kiwi.
Although Kiwi’s technically have feathers, they are shaggy and hair-like and unlike the feathers of any other birds. Also unlike other birds, Kiwi’s have long sensitive bristles around their face and the base of their beaks.
Colour
North Island Brown Kiwi tend to have a grey-black head and neck with a dark reddish-brown body streaked with black and a paler grey-brown underbody. This colouration is very much a generalisation as Kiwi have been spotted in a wide range of colours from dark red through to pure white.
Other Features
Most birds have little or no sense of smell but Kiwi have such a well developed sense of smell they are able to find food using smell alone. There are even reports of Kiwi in captivity sniffing out their food and refusing to eat anything that was prepared by someone other than their usual feeder.
Kiwi also have well developed hearing and have been seen turning their heads from side to side to better locate the source of soft noises. These heightened senses are important to the Kiwi as they have very small eyes and poor eyesight. Being mostly nocturnal they avoid bright light, only coming out once it is dark. In Northland Kiwi have been spotted out during daylight hours, but this generally only occurs during periods of prolonged drought when the Kiwi are having such a hard time finding water that they will risk venturing out during the day.
The skeleton of a Kiwi is also unusual compared to most birds and in some ways is more similar to the skeletons of mammals. The bones of most birds contain air sacs, making them as light as possible to enable flight. As Kiwi’s don’t fly, light bones are not a requirement and instead their bones are filled with marrow. The eye sockets of Kiwi’s are separated by large nasal cavities, the same as humans and other mammals. Most birds do not have nasal cavities, which is why they have no sense of smell, and instead their eye sockets are separated by a plate.
Kiwis are unique even compared to other ‘ratite’ species in that they have four toes while most of the others have only two or three.
Sound
Being nocturnal, shy and well camouflaged, Kiwi are usually heard rather than seen. As they feed on the forest floor they make snuffling noises that can be heard several meters away. This noise is the Kiwi forcing air and dirt out of their nostrils as they probe the ground for insects.
The call of the male Kiwi is a series of 7 to 23 long, shrill whistles that ascend and descend slightly. The female’s call is shorter and hoarser. Each species of Kiwi has a slightly different contact call but they are so similar that even Kiwi’s get confused, with Kiwis being know to answer calls from another species.
When frightened or in an aggressive mode Kiwis will growl, hiss and snap their beaks loudly to warn away rivals or predators.
Behaviour
Like all Kiwi, the North Island Brown Kiwi are nocturnal. During the day they will rest in a burrow in the ground, a hollow in a tree or log or hidden away under thick vegetation, emerging only once darkness has descended. They will spend the night foraging for food, calling occasionally to advertise their territory or maintain contact with a mate.
Although it is not known how large a Kiwi’s territory is, they are territorial and will defend their territories using their strong legs and sharp claws. The males will care for their young until they are old enough to fend for themselves, at which point he will chase any male chicks from his territory to avoid competition with them in the future.
Feeding
Kiwi seem to prefer worms and insects but are in fact omnivores. During one research project the stomach contents of 40 North Island Brown Kiwi were analysed and found to contain;
- Freshwater Crayfish or Koura,
- Earthworms,
- Woodlice,
- Millipedes, and centipedes,
- Slugs, snails and spiders,
- Seeds and berries, and
- Fibrous, grass-like plants
Not only are Kiwis the only bird that has nostrils at the tip of their beak, they are also the only birds with sensory pits on their beaks. When searching for prey they will walk along, tapping at the ground, waiting for the sensory pits to detect the vibrations made by worms and insects moving around underground.
When they detect a worm, Kiwis will use their bills to probe into the worm’s tunnels. Using a back-and-forth levering action they will enlarge the hole until they find the worm, snuffling away while they are at it to clear the dirt from their nostrils. The holes they create can be as deep as 120mm and as wide as 100mm.
Breeding
Kiwis are not known for making any kind of formal display to attract a mate. The males will fight vigorously over a female but it is usually the larger female who will decide when she wants to breed. Once the two pair-up, the male, with some help from the female, will prepare a nest. He will dig a burrow underground or find a hollow in a tree or crack in a rock which he will line with vegetation.
Kiwis can breed throughout the year but egg laying tends to peak from June to November. The female will feed up in the days leading up to laying but will stop eating one or two days before laying her first egg. If she has two eggs, the second will be laid 33 days after the first.
A Kiwi’s egg is as much as 20% of the Kiwis body weight, making it the largest egg, proportional to the size of the female, of any other bird. It also contains significantly more yolk than the eggs of most birds; 65% yolk compared to most eggs with 35-40%.
During the first few weeks the egg is either incubated by the female or left unattended for several days at a time. After that, the male incubates the eggs on his own for 71 to 84 days before the first egg hatches. During this period, the male’s ability to get out and feed is limited but he has enough fat reserves to get him through this time of fasting. When the male does leave the nest to feed or drink, he will cover the eggs and the entrance to the burrow with vegetation.
When the chicks eventually hatch, breaking through the shell with their feet, they are unable to stand. It is not until four days after hatching that they are able to stand up and another two days before they are able to walk with any confidence.
The male will bring food into the burrow and feed the chicks for the first six to eight days of their lives. After this, the chicks will leave the nest and forage with the male.
The chicks will reach their adult size at 12 months old. It is not known how long Kiwi’s can live for but some Kiwi’s living in captivity have survived for 20 years or more.
Distribution and Habitat
The Kiwi’s primary habitat is dense native forest, like that found in the Tangihua Forest, however they have been able to adapt to a range of different habitats, including those produced by humans. Kiwis have been found living in regenerating manuka scrub, moving out into farm land at night to feed, and thriving in planted pine forests. Their habitat ranges from high up in alpine meadows down to sea level where they have been filmed happily foraging for insects on the beach
Threats and Conservation Plan
Māori hunted Kiwi for their meat and their feathers, that were turned in to prized cloaks. Kiwi weren’t the preferred species for food so weren’t targeted to the point that they started to seriously decline.
Early European collectors hunted Kiwi and sent both live and dead birds back to European museums and zoos. This was also fairly minor and wouldn’t have had a major impact on the species.
The decline of Kiwi started when predators such as rats, stouts and cats were introduced, large scale forest clearing started and when large numbers of Kiwi were hunted in the mid to late 1800’s to make trimming and muffs for the London fashion houses. Most of this hunting was done on the West Coast of the South Island, with the Little Spotted Kiwi being the main target.
Now that hunting Kiwi as been made illegal, the main threats to the Kiwi’s survival are introduced predators, such as cats, rats and stouts that kill young Kiwi, dogs that can kill mature Kiwi, loss of the habitat they need to survive and accidental killings by motor vehicles and possum traps.
Kiwi are functionally extinct, if not totally extinct, in the Tangihua Forest. The forest itself is the ideal Kiwi habitat, it is the predators that occupy the forest that prevent them from thriving. In order to save the Kiwi in the forest, the rats, cats, stouts and ferrets need to be removed.
The Tangihua forest block is managed by the Department of Conservation (DOC). They currently do not have the funding available to put in place the strategies needed to eradicate pests and protect the forest.
The Tangihua Lions Lodge has set up the following programs that you can be a part of;
Tangihua Community Pest Control Area: Targeting pests on farm land with local farmers and the Northland Regional Council
Conservation on DOC Land: Tangihua Lions Lodge Conservation and Education project
Conservation Education: Creating a high quality, accessible educational center surrounded by a fully functional ecosystem for schools and any one else who may choose to use the facility. Volunteers Options : How you can help protect our native bush
References
this article was wrtten by Rachael Mannion
It is very apparent that specific information has been shared online between many organisations. Attributing to the initial source is impossible. As much as possible we have used our own photo’s and the following websites have been used as sources for our information;
- Te Ara The Encyclopaedia of New Zealand,
- Wikipedia
- DOC website, and
- T.E.R:R.A.I.N Taranaki Educational Resource: Research Analysis and Information Network
