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Friday, January 19, 2018

Species Fact Profile: North Island Brown Kiwi (Apteryx mantelli)

North Island Brown Kiwi
Apteryx mantelli (Bartlett, 1852)

Range: North Island of New Zealand
Habitat: Temperate Forest, Scrub
Diet: Earthworms, Insects, and other terrestrial invertebrates
Social Grouping: Pairs are territorial, especially during breeding season
Reproduction: Monogamous (sometimes for life).  May lay at any time of year, but usually June through November.  Nest in hollow logs, burrows, or rock crevices.  Usually single egg (if a second, it is laid up to a month after the first), with up to 3 clutches per year.  Egg incubated by male for 75-90 days (left unattended at night while male goes off nest to feed).  Chicks venture out of nest a week after birth, but stay close to nest until 4-6 weeks old.
Lifespan: 40 Years (Captivity)
Conservation Status: IUCN Endangered

  • Body length 40 centimeters.  Weigh 1.5-3.2 kilograms, with females larger than males
  • Spiky brown plumage (resembling hair more than feathers), often streaked with reddish-brown.   The long, thin beak is off-white.  The species is flightless, and the wings are extremely small, barely visible.  No tail.
  • Nocturnal, spend the day in burrows that are dug with their powerful claws
  • Communicate with a whistling call - male call is higher-pitched, faster than female whistle
  • Lay one of the largest eggs compared to their body size of any bird species, approximately 15% of the mother's body weight
  • Unlike many birds, kiwis have an excellent sense of smell, using smell to find prey.  Their nostrils are located near the tip of the beak.
  • Previously considered to be same species as Apteryx australis and Apteryx rowi; some taxonomists still list them as one species
  • National bird of New Zealand; New Zealanders often refer to themselves as "Kiwis"
  • Tremendous decline in population, having lost as much as 90% of their rang.  Primary threat is the introduction of mammalian predators (dogs, cats, stoats) to New Zealand, where previously none existed.  Habitat loss is also a major threat.  Sometimes killed by poison bait set out to kill invasive possums
  • Conservation measures include predator removal, captive-breeding and reintroduction, and head-starting chicks until they are large enough to be safe from predators

Zookeeper's Journal: Perhaps the most unbirdlike of birds, the kiwis of New Zealand are sometimes known as "The Honorary Mammals."  For all of their fascinating adaptations (and adorable appearances), the kiwis make poor exhibit animals.  They are nocturnal and cryptic, and the best I've ever seen in a zoo display was a slouching shadowy figure scurrying across the back of a dark exhibit.  So where did I get the picture above?  Back when it was still open, the National Zoo's Bird House used to offer a "Meet a Kiwi" program, where a keeper would bring out a special ambassador kiwi for a few minutes three times a week.  The bird, specially selected for his temperament, would sniff around a small enclosure and eat some worms, all while zoo staff highlighted the unique awesomeness of the kiwi.  The Bird House has since been shut as part of renovations, and when it reopens, it is my understanding that kiwis will not be displayed (though they are still maintained at the Smithsonian Conservation Biology Institute).  Which is a pity - those encounters were probably the only way that I ever would have had to experience close-up one of the world's most remarkable birds.

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