Apteryx haastiigreat spotted kiwi(Also: roroa)

Geographic Range

The great spotted kiwi is indigenous to South Island, New Zealand. They are found in the snow-covered peaks, mountain forests, and alpine tussockland west of the Main Divide from Tasman Bay to south Westland. (McLennan, et al., 1990)

Habitat

Kiwis reside mainly in the alpine and subalpine areas of northwest New Zealand. Efforts to introduce the birds to other habitats outside of this small region have never been successful.

Physical Description

Kiwis are pear-shaped, flightless birds that possess rudimentary wing structures. They have small heads and necks, with long, slender bills that are excellent for capturing insects and other small prey; the base of the bill is surrounded by cat-like wiskers. Kiwis have a powerful sense of smell, and rely primarily on their nostrils, rather than eyes for hunting. Kiwis also have excellent hearing; their ears are so well developed that they can be seen easily through the head feathers.

The bird's plumage is composed of extremely soft, hairlike feathers, which have no aftershafts; the texture is comparable to the fur of a rodent, rather than the feathers of a bird. The plumage is mottled charcoal gray to light brown.

Kiwis have extremely powerful legs and claws, these structures are used for defensive and offensive behavior; the birds are fast runners and also fierce fighters when necessary.

Kiwis have an average body temperature of 100 degrees F, much closer to that of a human being than to other birds. Kiwis also have heavy, marrow-filled bones, unlike their airborne relatives.

Overall, kiwis are considered very un-birdlike oddities; in fact, zoologist William Calder refers to them as 'honorary mammals'.

In terms of size and weight, distinct sexual dimorphism exists between males and females of this species. Males are usually 2.5 to 3 kg and 45 cm in height, with a bill length of 95 to 105mm. Females weigh 3.5 to 4 kg, are about 50 cm tall and have a bill length of 110 to 120 mm. (Grzelewski, March 2000; McLennan, et al., 1990)

  • Sexual Dimorphism
  • female larger
  • Range mass
    2.5 to 4 kg
    5.51 to 8.81 lb

Reproduction

Kiwis are strictly monogamous birds; they usually pair off for at least 2-3 breeding seasons, sometimes for life. (Grzelewski, March 2000; Heather and Robertson, 1997; McLennan, et al., 1990)

Breeding takes place during late autumn, and the gestation period before egg-laying is about one month. A characteristic which distinguishes great spotted kiwis from all other kiwi species is the ability to produce only one egg in a year. Northern brown kiwis can produce up to six eggs in a year, while the great spotted kiwi's egg requires so much energy to produce that it is only possible once a year. The egg takes anywhere from 75 to 85 days to hatch, and the chick spends 2 to 3 days simply trying to extricate itself from the shell. During the first 3 days of life, the chick's belly is so distended by its yolk sac that movement is impossible. For the first 6 weeks of life, a chick may feed during daylight hours, but after this time it becomes exclusively nocturnal. Kiwi chicks are defenseless until they reach a weight of about 1.75 pounds, which takes 17 to 20 weeks; before this time, most chicks are killed by predators such as stoats and weasels. Kiwi growth continues until the sixth year of life, but sexual maturity has been reported as early as two years of age in females and fourteen months in males. Unlike many other birds, female kiwis have a pair of functioning ovaries, rather than just one. (Grzelewski, March 2000; Heather and Robertson, 1997; McLennan, et al., 1990)

  • Range eggs per season
    1 (high)
  • Range time to hatching
    75 to 85 days

Egg production is an exhausting process for the females; they will produce a single egg that reaches 1/4 their body mass. Females cannot eat while gestating, because the egg takes up so much space within the body; therefore, they must use stored fat accumulated over a period of five months previous to fertilization to create the large, nutrient-rich egg. Gestation is uncomfortable for the mother, and generally movement is very restricted during this time. In order to relieve the inflammation and discomfort caused by gestation, a female kiwi will often soak her abdomen in cool puddles when she ventures out of the burrow. After the egg is layed, males are responsible for incubation. They will leave the egg only to hunt for a few hours during the night; at this time the females guard the egg. Kiwis are precocial birds, emerging from the egg looking like miniature adults; after hatching, chicks are abandoned by the parents and within ten days it begins to hunt for food outside the burrow. (Grzelewski, March 2000; Heather and Robertson, 1997; McLennan, et al., 1990)

  • Parental Investment
  • precocial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female

Behavior

Kiwis are extremely territorial; once a mating pair forms, the two kiwis defend their nesting region fiercely. Generally, this region is 25 hectares in size -- how the diminutive birds manage to police this huge amount of land is not fully known, but calling rituals are thought to be a key factor. Kiwis, especially males, are extremely aggressive when their territory is invaded; the birds' legs and beaks are dangerous weapons and can be used to fight till the death. However, encounters between kiwis that involve injury or death are rare; territories rarely change 'ownership' unless the resident male dies (naturally) or is crippled.

Kiwis live in excavated burrows, which are created several weeks before they are used; this allows the moss and earth to be naturally reestablished, so that the burrow is well camouflaged. The birds may have up to a hundred different shelters within their territorial range, and usually use a different one each day. Kiwis do not leave their burrows during the day unless forced out by danger; they are extremely aggressive by night, but shy and timid by day. (De Roy, May/June 1997; McLennan, et al., 1990)

Home Range

In the most densely populated areas of the forests, one may find four to five kiwis in a square kilometer.

Communication and Perception

Food Habits

Kiwis are exclusively nocturnal; they begin their nightly hunt for food approximately 30 minutes after sunset. The birds consume insects, snails, spiders, earthworms, crayfish and fallen fruits and berries. They sense prey by tapping the ground with their sensitive beaks and sniffing the earth while walking silently through the brush. To capture underground insects, these birds shove their beaks deep into the ground while stabbing back and forth. (Heather and Robertson, 1997)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • terrestrial worms
  • Plant Foods
  • fruit

Economic Importance for Humans: Positive

Kiwis are a beloved symbol of New Zealand culture, although they are rarely seen by humans. At home and abroad, New Zealanders are known as 'kiwis'. No other creature has given its name both to a nation's inhabitants and its cultural identity so completely as the kiwi bird. Commercially, the animal's image is used to sell New Zealand to the rest of the world. The kiwi appears on postage stamps, coin backs, and corporate logos; it promotes breakfast cereals, the national lottery, and an airline. The kiwi is a popular mascot as well as being a financially significant part of New Zealand's business and tourism industries. (Grzelewski, March 2000)

Economic Importance for Humans: Negative

There are no known negative effects of kiwis on humans.

Conservation Status

Due to the kiwis' general shyness and nocturnal behavior, few New Zealand residents have encountered their national mascot in the wild. It is no wonder then that the human population was ignorant of the drastic decline in kiwi population over the past several hundred years. Approximately 1,000 years ago, an estimated 12 million kiwis roamed the forests of New Zealand; in 1996 biologists discovered that the population had dwindled away to less than 70,000 birds. Until recently, kiwis were disappearing at a rate of 6% per year; this drop is due almost entirely to predation by stoats, weasels and ferrets -- non-indigenous animals which were introduced to New Zealand by European settlers near the turn of the 20th century. At this point, efforts are being made to recover kiwi populations all over New Zealand; in 1991 the Kiwi Recovery Programme was launched. The efforts of this program have resulted in a promising rise in the number of kiwi chicks that survive to adulthood; from 5% survival rate in 1991 to 60% since 1998. Strategies used to repopulate the region have included breeding in captivity, but scientists are discovering that elimination of the introduced predators has been the most important factor. Kiwis are incredibly hardy animals, who reproduce constantly; they are susceptable to few natural illnesses and are able to withstand drastic environmental conditions. With luck and continued efforts on the part of conservationists, it is hoped that the kiwi will remain a part of New Zealand for many years to come. An essential aspect of the recovery program is public awareness and support ( http://www.kiwirecovery.org.nz/). (Grzelewski, March 2000)

Contributors

Carrie Matherly (author), University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

young precocial

young are relatively well-developed when born

References

De Roy, T. May/June 1997. "National Wildlife Federation; New Zealand's Bizarre Un-Bird" (On-line). Accessed March 18th, 2000 at http://backstage.nwf.org/nwf/intlwild/kiwi.html.

Grzelewski, D. March 2000. Night Belongs to the Kiwi. Smithsonian, Volume 30, No. 12: 79 - 86.

Heather, B., H. Robertson. 1997. Field Guide to the Birds of New Zealand. New York: Oxford University Press.

McLennan, J., R. Harris-Ching, E. Fuller (Editor). 1990. Kiwis: A Monograph of the Family Apterygidae. Auckland, New Zealand: Seto Publishing.