The maintenance and reproductive behaviour of black stilts (Himantopus novaezealandiae) in captivity, and implications for the management of this rare species : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Zoology at Massey University
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In an effort to conserve New Zealand's rarest endemic wading species, the black stilt (Himantopus novaezealandiae), eggs were removed from the wild in October 1979 for establishment of a captive breeding population. Eight chicks fledged following artificial incubation and hand-rearing at the National Wildlife Centre near Masterton. At two years of age, these tentatively sexed stilts were formed into pairs and housed in large outdoor enclosures. I studied their behaviour from December 1982 until February 1986, aiming to i) collate an ethogram for the species under the restrictions of a captive environment ii) describe and quantify behavioural activity, especially that of reproductive behaviour and breeding biology iii) describe vocalisations and iv) on the basis of observed behaviour, examine captive breeding as a management option for black stilts. A repertoire of 38 context-specific behavioural patterns were observed throughout the year and a further 15 stereo-typed species-typical nest-building, copulatory, incubation and chick-rearing patterns occurred during the breeding season. Time-budget analysis of a focal pair of stilts showed foraging and immobility to be the predominant daily activities, peaking during the pre-nesting period. A bimodal diurnal distribution of foraging activity was observed, peaking in the early morning and mid-late afternoon. Time allocated to foraging and immobility was inversely related to the time spent in incubation. While all stilts showed incipient breeding behaviour, only one pair bred. Multiple laying of this focal pair was induced by subsequent clutch removals. This pair produced 10 clutches of eggs over three breeding seasons, with a maximum of five clutches being laid in one season. Laying spanned the period from 18 September to 28 January. The mean clutch size was 3.27 and the mode was 4.0. Fertility was 90.6% in captivity and 95.6% in the wild. Following egg removal, re-laying took place within 8-13 days (mean and mode 9 days). The male did the most incubating, especially in the first five days after initiation of egg-laying by the female. Eight chicks were reared successfully by this pair over the three years. Captive chick growth was faster than that of wild chicks and they fledged earlier (at 35-36 days). They exhibited similiar antipredator behavioural patterns to wild chicks and their response depended on age of the chick and type of predator. Eleven adult and four juvenile vocalisations were structurally described. These categories were both intergraded or discrete and call parameters were variable within and between call types. Variation within one call type (alarm yap) was greater between individuals (wild and captive) than within individuals. Interspecific variation between pied stilt (.!h_ himantopus leucocephalus) and black stilt alarm calls was also greater between species than within them. Hybrids of the two stilt types were intermediate in call structure, but considerable structural overlap with that of pied and black call parameters was evident. Based on the observed behaviour and breeding biology of captive stilts, I propose a novel management strategy which involves the establishment of a captive breeding facility for this species within their natural range in the Upper Waitaki Basin.
Himantopus, Reproduction -- Research, Rare birds -- New Zealand, Breeding