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Black
Stilt (Himantopus novaezelandiae)
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Maori Name: Kaki |
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Length:
38 cm |
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Distribution: Nests in the McKenzie
Basin. Occasionally seen in northern estuaries. |
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Food: Wide variety of aquatic insects and their
larvae. Worms, grubs, fish. |
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Voice: High pitched yapping when
alarmed. |
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Breeding: September,
October. By rivers or tarns. Scrape in shingle with varying amounts of nesting material. Four brown eggs blotched with
blackish-brown. Incubated for 25 days by both adults. Chicks fledge in six to eight
weeks. |
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Endemic and endangered the Black Stilt has been steadily losing ground to the Pied
Stilt. Once found throughout New Zealand it is now confined to a small area of the McKenzie
Basin. Less than 100 pure Black Stilts remain although captive breeding programmes at the National Wildlife Centre and at Twizel
hold out some hope the species will not totally disappear. |
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There are a
number of difficulties to overcome if the population is to remain viable.
With so few birds every adult Black Stilt is vital to help continue the
species. Unfortunately some hybridise with Pied Stilts, so losing the
opportunity to add young pure Blacks to the meagre population base.
Another difficulty is that nesting alone, they are more vulnerable to
predators. A colony of Pied Stilts with their frantic injury feigning
displays have a good chance of distracting an intruder. Not so for the
Black Stilt whose lone distraction display is weak by comparison with the
Pied Stilt's, making them more vulnerable to cats (the main problem)
ferrets, stoats, rats, and harriers. Rabbit poisoning has been a problem.
With fewer rabbits, Black Stilts have become special targets for
predators. Trap lines around major breeding grounds helped minimise this
risk and the Department of Conservation also artificially incubated eggs
leaving a dummy clutch which foiled predators seeking a meal. When they
were about to hatch, the eggs were returned and so a three week period of
great vulnerability was eliminated. Sometimes double-clutching is practised with the first clutch being hand
reared. Unfortunately Black Stilts choose sites prone to flooding and some nests are lost in this way.
Three or four brown eggs, blotched with brownish black are laid and incubated by both adults for 25
days. September and October is the usual time but if a clutch is lost another will probably be laid late in October or November. Adult Black Stilts care for the chicks until they fledge at six to eight
weeks. Family groups stay together during the winter defending a feeding area but young are driven away as spring
approaches. Black Stilts feed on mayfly and damsel fly larvae and worms, flies and small
fish. Unmated birds migrate to coastal areas and have been seen in several North Island
harbours. Very occasionally a Black or hybrid Black Stilt nests away from the McKenzie
Basin. During 1986 three Black Stilts built nests in different locations around Lake
Ellesmere. All were associated with Pied birds but none was successful. |
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