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North Island Brown Kiwi - The following information comes from the Smithsonian National Zoo which keeps a pair of North Island Brown Kiwi:
Order: Apterygiformes
Family: Apterygidae
Genus/Species: Apteryx mantelli
The nocturnal flightless North Island Brown Kiwi is so remarkably unbirdlike in appearance and behavior that is has sometimes been referred to as an "honorary mammal." The kiwi's "fur" is actually a thick covering of shaggy hair-like grey-brown feathers. The useless vestigial wings (4-5 cm long) are completely hidden under the plumage. They have no external tails. The wide spacing of their robust sharp-clawed legs gives them an amusing rolling gait. Kiwis are stout birds, standing 50 cm tall with females (2,060-3,850 grams) weighing up to 30 percent more than males (1,440-3,060 grams).
Most of the world's birds have excellent eyesight and a poor to non-existent sense of smell. Kiwis reverse this usual arrangement. It is estimated that they can see only two feet ahead of them in daylight, and six feet at night. The kiwi's long (up to 20 cm) pale grey-brown bill is unique in the bird world in having the nostrils located near the tip. They smell their prey rather than see it. A few feathers around the base of the bill are highly modified to form long tactile bristles. These rictal bristles help the bird feel its way around in the dark, compensating for the relatively poor eyesight. Though their eyes are small, their ears are unusually large.
The name kiwi is derived from the ringing call of the male. Females respond with a hoarse throaty call which has been likened to the sound caused by opening an extremely old rusty barn door. These calls allow the pair to mark their territories and remain in contact while foraging separately. Both sexes can produce an assortment of grunts, growls, and hisses and often snuffle audibly when searching for food. The snuffling may be produced by the opening and closing of a valve behind the nostrils that prevents the bird from inhaling dirt and debris as it probes the soil and leaf litter.
There are five kiwi species: the North Island Brown Kiwi, Great Spotted Kiwi, Lesser (Little) Spotted Kiwi, Rowi, and Tokoeka. All are endemic to New Zealand. The National Zoo exhibits the North Island Brown Kiwi. These kiwis are found from sea level to 1,200 meters. Their original habitat was moist coniferous forest dominated by kauri and tree-ferns. Clearing of much of this primeval forest has forced many kiwis to attempt to survive in partially timbered agricultural areas. The largest remaining population of Brown Kiwis on North Island resides in a large commercial pine plantation.
Kiwis form life-long pair bonds and exhibit remarkable fidelity to their home territories. They will remain in a territory for weeks after every tree has been logged. Territories range in size from five to 50 hectares depending on the quality of the habitat. Kiwis excavate several burrows within each territory. A typical underground burrow has one entrance, a tunnel 20 to 200 cm in length and a terminal chamber large enough to accommodate both birds. They will also utilize hollow logs or shallow holes dug out between tree roots.
Brown Kiwis have an extremely varied diet which includes earthworms, beetles, snails, crayfish, insects, fruits, and berries. The unique bill is used to sniff out food as the bird forages by plunging it repeatedly into the leaf litter of the forest floor in search of prey. They forage actively from dusk to dawn.
Kiwi nests are usually located in well established burrows where the surrounding foliage has had time to grow up and thoroughly conceal the entrance. The female Brown Kiwi lays one or two glossy white eggs of prodigious size, 14-20 percent of her body weight. Producing such a large and energy rich (more than 60 percent yolk) egg depletes the female’s energy reserves. There is a period of 25 to 30 days between the laying of the first and second egg. It is entirely understandable that she leaves the male alone in the nest burrow to handle the 70- to 80-day incubation by himself.
Kiwi chicks have no egg tooth and must use their feet to kick their way out of the shell. A newly hatched kiwi looks like a mini replica of the adult, at 1/8 adult size. They are precocial chicks, able to forage for themselves with only minimal paternal supervision for their first few days of life. Although completely independent by two weeks of age, they do no reach adult size until they are 18 to 20 months old.
Technical Specifications
Silver Content (Troy oz): 1
Monetary Denomination (NZD): 1
Fineness (% purity): 99.9
Minimum Gross Weight (g): 31.653
Maximum Diameter (mm): 40.60
Maximum Thickness (mm): 4.00
According to some estimates, only about 3000 of these coins were actually issued in 2006.