We compared the behaviour, energy expenditure, and food intake of male and female South Island pied oystercatchers, Haematopus ostralegus finschi, breeding in pasture and crop paddocks in Canterbury. In this monogamous species, females spent more time inactive than males (P=0.03) and there was a trend for males to spend more time in territory defence than females (P=0.08). There were no significant differences in other behaviours and the sexes did not differ in their food intake rates. We used literature values for this species to estimate the energy expended in each activity and the energy expenditure rate over the breeding season. Despite the differences in the proportion of time spent in territory defence and inactivity by the sexes, males had a lower rate of energy expenditure than females over the breeding season (P=0.07). We suggest that behavioural differences are unlikely to compensate female South Island pied oystercatchers for their costs of gamete production and the difference in energy expenditure may reflect the uncertainty of paternity of males.
Nesting pairs of brown skuas (Catharacta lonnbergi), black-backed gulls (Larus dominicanus), red-billed gulls (Larus novaehollandiae), white-fronted terns (Sterna striata), Chatham Island oystercatchers (Haematopus chathamensis) and shore plovers (Thinornis novaeseelandiae) were counted during 10 seasons on Rangatira (South East) and Mangere islands of the Chatham Islands. It was concluded that the small numbers of skuas, oystercatchers, and shore plovers on the islands was a result of habitat shortage, but that populations of the colonially-breeding gull and tern were constrained by food limitation in the surrounding seas. Whereas skuas, black-backed gulls, and terns nested in the open with conspicuous nests the other shore species on the islands had concealed nests. Comparison with nesting on Chatham Island, the New Zealand mainland, and subantarctic islands suggested that concealed nesting by red-billed gulls, oystercatchers and shore plovers was most likely in response to the presence on the islands of the predacious brown skua.
The blue penguins (genus Eudyptula) have been subjected to extensive taxonomic revision. In 1976, the genus was reduced from 2 species to a single species (Eudyptula minor) with 6 subspecies, based on a morphometric analysis. Despite the later proposed rejection of the differentiation of subspecies in Eudyptula minor, following analysis of allozymes in some populations, the 6 subspecies have continued to be recognised in some popular and scientific literature. We compared the sequences of 3 mitochondrial gene regions (small ribosomal subunit, cytochrome oxidase b and the control region) from the 6 hypothesised subspecies to examine relationships within Eudyptula. We found evidence for 2 unexpected clades: the 1st consisting of Otago and Australian populations, the 2nd consisting of north- ern, Cook Strait, Chatham Island, and Banks Peninsula populations. Some support for these 2 clades was also found from a re-analysis of morphometric data and from a preliminary examination of vocalisations.
Brown teal (Anas chlorotis) populations at Clendon Cove and Tutaematai in Northland, New Zealand, declined catastrophically between 1993 and 1995, from 31 pairs to 1 and from 22 pairs to 8, respectively. Mean productivity was 1.8 fledglings pair1 in both populations. Fledgling survival was almost nil with only 1 of 51 identifiable fledglings surviving to recruit into 1 population. Almost all fledgling mortality occurred within 3 months of independence. Annual adult survival was 15% at Clendon Cove and 43% at Tutaematai and most deaths occurred in October-December, immediately after breeding. At Clendon Cove, significant mortality also occurred in autumn. Destruction of breeding and refuge habitat by cattle seeking moisture during periods of drought was identified as a significant cause of decline.
Reports of dispersal by juvenile weka (Gallirallus australis greyi) on the North Island are rare. Estimates of the distance dispersed and the rate of survival of dispersers are important factors to be considered for weka conservation. I captured 20 young weka during a 2-year study and attached radio transmitters to 4 of them. In addition, I was able to measure the distance travelled by 3 banded weka that were either recaptured or seen again, and 1 weka that was recovered dead. Newly independent weka used a part of their parental home range at first, then moved up to 3.5 km. Two-stage dispersal, where young weka leave their parents but remain close by and move away later, has been reported on offshore islands: my results are consistent with that type of dispersal. More research is needed on weka dispersal because it is likely to be linked to factors important for their conservation and management.
A species of small procellariid known locally as titi, probably the black-winged petrel (Pterodroma nigripennis), nested into the historic period in burrows in the volcanic soil of the uplands of Mangaia in the southern Cook Group. The demise of this titi as a breeding bird on Mangaia was probably caused by a combination of the detrimental effects of human harvesting and various introduced mammalian predators which were present on Mangaia after the arrival of missionaries in the early nineteenth century.