The population status of the Chatham Island tomtit (Petroica macrocephala chathamensis) was determined for each island of the Chathams group, east of New Zealand. Also, the breeding biology of the population on Rangatira (South East Island), which is free of introduced mammalian pests, was determined from observations made during 8 breeding seasons, 1981/82 to 1988/89. The total population of the Chatham Island tomtit is estimated to be < 1000 birds: Chatham, extinct; Pitt, c. 500; Rangatira, 200-300; Mangere, 70-100; Tapuaenuku (Little Mangere Island), occasional vagrant. Regeneration of scrub and forest habitats on 3 islands is likely to lead to gradual increases in the tomtit populations there. The nesting season on Rangatira was from late September to late January, which was just sufficient time for a pair to rear 2 broods successfully. Of 378 nests, 43% were in tangles of pohuehue (Muehlenbeckia australis) vines, 16% in cavities, 12% on a branch, trunk, or stump covered in vines, and for 21% the site was not indicated. The mean height of nests was 2.7 m, and the mean duration of the pre-laying period was 5.9 days. Mean clutch size was 3.1 eggs, and incubation usually started on the day the last egg was laid (82%). Only females were seen incubating, with males feeding their mates at regular intervals. Of 97 eggs, 83% hatched, and 93% of 15 nesting attempts resulted in at least 1 fledgling each. The high nesting success, in comparison to that of mainland populations, is attributed to the absence of mammalian predators on Rangatira. Although our study provided much information for the early stages of the nesting cycle, few data are available for other aspects of the Chatham Island tomtit’s breeding biology, such as length of incubation, and nestling and fledgling periods.
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.
North Island kokako (Callaeas cinerea wilsoni) appear sexually monomorphic. Females are, on average, slightly smaller than males in most body measurements. Mean tarsus length was significantly smaller among females at all sites and can be used to predict sex of unknown birds with up to 86% accuracy. A simple discriminant function, using tarsus and wing chord measurements, was derived which increased sex resolution to over 90% at some sites. This is sufficient accuracy to provide a useful field technique for kokako research and conservation management. Best discriminant functions for different sites are presented and their geographical limitations are discussed.
The yellow-eyed penguin (Megadyptes antipodes) on the South Island of New Zealand was believed to have suffered a population decline that continued into the 1980s. Unpublished census results from L. Richdale (1930s-1950s) and S. Sharpe (1950s-1960s) for Otago Peninsula show that there were only 44 nests in 1940, but the number increased in the 1940s-1960s. Numbers peaked at 276 nests in the mid-1980s. Subsequent decreases and a crash to 79 nests in 1990 led to concerns for the viability of the population, but years of good survival and breeding allowed a recovery. The fluctuations were probably driven by interplays of human impacts and environmental variation. Reservation of breeding areas, revegetation, and predator control have reduced the deleterious human impacts and given the species a chance to increase numbers and withstand adverse fluctuations in the environment.
We investigated the effect of jetboat wakes on feeding wrybill (Anarhynchus frontalis), banded dotterel (Charadrius bicinctus), black-billed gull (Larus bulleri), and black-fronted tern (Sterna albostriata) on the Dart River, Otago. We found that all species feed in areas likely to be affected by jetboat wake. On average, banded dotterel (n=8) were 43.2 mm above the water level and 4.37 m from the waters edge, wrybill (n= 16) were 49 mm above the water level and 0.8 m from the water’s edge. Jetboat wake (n=7) extended 91.3 mm above the waters edge and on average 1 m from the edge of the river channel. The implications of the wash and the extent of the likely effect are discussed.
An annotated checklist of the bird species of Niue Island in the southwest Pacific is provided from published and unpublished sources, and from observations during April-May, September, and December 1994. Results for common species were derived from five-minute counts, numbers seen per kilometre while travelling by motorcycle along roads, and single species surveys. The number of species on Niue is 31 (6 seabirds, 10 shorebirds, and 15 land birds). The common noddy (Anous stolidus) was confirmed as nesting on the island. Recommendations are made for the future management of the hunted Pacific pigeon (Ducula pacifica) and the scarce blue-crowned lory (Vini australis).