breeding success

Supplementary feeding has proven to be a successful conservation tool for many species, including New Zealand’s hihi (stitchbird, Notiomystis cincta). Previous research has shown supplementary feeding to substantially increase hihi reproductive success at regenerating forest sites, but suggested that it would have reduced benefit in mature forest habitat. Here we report the first direct test of the effect of supplementary feeding on hihi reproductive success in mature forest, using data from the recently reintroduced population at Maungatautari Ecological Island.

To enhance the breeding success and survival of kaka (Nestor meridionalis) and mohua (Mohoua ochrocephala), we initiated stoat (Mustela erminea) control in the Eglinton Valley (13 000 ha), Fiordland, New Zealand using a single 40 km line of traps spaced 200 m apart with traps set continuously. This low intensity stoat control regime permitted successful kaka breeding and fledgling survival was high.

Norway rats (Rattus norvegicus) were present on Whale Island (Moutohora), Bay of Plenty, New Zealand between about 1920 and 1987. During 1969-1971 they reduced by less than 10-35 % the breeding success of grey-faced petrels (Pterodroma macroptera gouldi), by eating unattended eggs and killing young or weak chicks. Rabbits (Oryctolagus cuniculus), introduced to Moutohora (240 ha surface area) in about 1968, multiplied rapidly to reach a density of up to 375 individuals/ha by early 1973.

Egg and chick loss at banded dotterel (Charadrius bicinctus) nests was studied over the 1992/93 season on the Tekapo, Ohau and Ahuriri Rivers in the Central South Island. Egg loss at nests was higher on the Ohau and Tekapo Rivers than on the Ahuriri River, especially early in the season. Only 11% and 12% of nests fledged one or more chicks on the Tekapo and Ohau Rivers respectively, compared to 42% of nests on the Ahuriri River. Nests on islands within the braided riverbeds were more successful than nests on the mainland.

Age and structure of local vegetation (habitat complexity) are commonly assumed to be indicators of habitat quality for breeding birds, but for many species these relationships are poorly understood. The hihi (stitchbird Notiomystis cincta),an endangered New Zealand cavity-nesting passerine that only survives on mammalian predator-free islands or within fenced areas, has been the focus of intensive conservation management and research. Between 1992 and 2004 we examined the fledging success of 347 nests from four island populations.