During a visit to North Brother Island in Cook Strait from 11 October to 6 November 1990, we estimated by quadrat sampling that the 4 ha island supported 1000 pairs of fairy prions, 600 pairs of common diving petrels, and 225 adult tuatara. Most diving petrels nested below Coprosma scrub, and a few eggs were laid on the surface under dense shrubs. Many prion burrows were in more open vegetation. Burrows of both species were simple and were not shared with tuatara. Some evidence of tuatara preying on unattended eggs was found, but there was no evidence that the endemic Sphenodon guntheri, which is smaller than S. punctatus, fed on adults of either species. Many diving petrels, prions, fluttering shearwaters and red-billed gulls fed in tide rips close to the island. The position of each species in feeding assemblages was related to their dive depths. diving petrels in areas of strong currents submerged for only a few seconds at a time, but in areas of calm water dive durations averaged 29 seconds.
Pipit (Anthus novaeseelandiae) numbers on nine count routes in the Wellington region ranged from 0.16 to 6.22 per km on average. Estimated densities in regions with some favourable habitat varied between 1.0 and 2.5 per square kilometre. Highest numbers were in the hills south and west of Karori, and on the southern and western beaches between Owhiro Bay and Titahi Bay. Densities were lower over the rest of the region due to intensive farming, unfavourable plant succession pathways to bush, and urban development.
On Ewing Island, Auckland Islands, during the austral summer of 1991-92, Auckland Island teal Anas aucklandica aucklandica were dispersed principally as pairs occupying and vigorously defending small all-purpose territories. Most territories were around the margins of the island, either within a narrow fringe of grassland, or at the very edge of Olearia lyallii forest with access to boulder beaches or low wave platforms. Few territorial pairs lived entirely within the forest. A small number of juveniles and unpaired adults assembled as a flock at one protected coastal location where food was super-abundant, but other unpaired birds appeared to live furtively around the margins of occupied territories. Some non-territorial pairs persistently tried to occupy sections of shoreline in the face of defence by territorial pairs. Only territorial pairs were observed breeding. Females sited their nests on the ground well hidden from view above and laid eggs each of which weighed, on average, 14.8% of body mass. Mean clutch size in 45 nests was 3.4 eggs and hatching success of 86 eggs was 93%. Ducklings were first seen on 11 December and most broods had been reduced to a singleton within eight days of hatching. The probability of a duckling surviving from hatching to 30 days was 0.272. The estimated mean size of extant broods at fledging was 1.6. By estimation, only 14% of ducklings may survive to fledging, and up to two-thirds of all breeding pairs may fail to raise any young. Re-laying by unsuccessful pairs may extend the breeding season into April. Males contributed fully to care of the brood but were not always seen in close attendance. By comparison with other related Australasian teals, Auckland Island teal have a more terrestrial lifestyle and show more enduring territoriality.
Foraging flights of three female Auckland Island wandering albatross (Diomedea exulans gibsoni) were tracked from Adam Island in the Aucklands group by satellite radio telemetry. Two of the birds were incubating eggs, while the third was in the early stages of chick raising. All three birds made long flights of 11-13 days and 1000-1500 km into the Tasman Sea. The chick-rearing female also made shorter flights of less than 4 days and 900 km. The distances covered were similar to those recorded for other wandering albatross subspecies, but foraging strategies differed. Auckland Island birds initially flew fairly directly and at high speed, then seemed to slow down and change direction more frequently for a few days, before flying directly back to the Auckland Islands. Two explanations are suggested: birds may have been “commuting” to favoured foraging areas, or were blown by the winds. Speeds reached during the “commuting” phase were similar to those recorded for D. e. chionoptera, but were slower at other times. The Tasman Sea between latitudes 45°S and 40°S is an important foraging area for some female wandering albatross breeding on Adam Island.
Five surveys for the North Island kokako were carried out in the Hunua Range, Auckland between October 1992 and March 1994. Twenty six-28 kokako were recorded, including 3 possibly 4 pairs. Results suggest that there has been a decline in kokako numbers since the previous survey in 1986-1988. All kokako were recorded in tawa-podocarp forest. The birds ranged in altitude between 320 m and 640 m. Birds were distributed in the following catchments: Mangatangi (13 birds), Mangatawhiri (12 birds), Orere (2 birds), Tapapakanga (1 bird). Nearly all records (65%) were of birds heard rather than seen. Two pairs were seen.
We investigated foraging niche overlap in two allopatric and two sympatric island populations of Petroica species. We predicted that sympatric populations (black robins, Chatham Island tits) would have narrower foraging niches than the allopatric populations (South Island robins, Snares tits), and that the foraging patterns of the allopatric populations would tend to be intermediate between the sympatric populations. These predictions were not supported. Rather, the two robins and two tits foraged in ways very similar to each other, and in ways suggesting that “robin” and “tit” foraging styles are a conservative feature in the evolution of this group.
A survey of blue penguins (Eudyptula minor) in 1991-92 along the coast of Otago in the South Island found at least 2073 breeding pairs between the Waitaki River and Nugget Point. The total population in this area, including immature birds, is estimated at about 9300 birds. These birds use 20 breeding sites along the coast, but most (97%) are concentrated in four areas – Taieri Island, Green Island, Otago Peninsula and Oamaru. Birds no longer breed at seven sites, have decreased on Green Island and at one site on Otago Peninsula, remained largely unchanged at Nugget Point and have recently increased at Pilot’s Beach near Taiaroa Head, and possibly at Oamaru. Dogs killed at least 34% of birds breeding in one part of Oamaru. Most nests were in depressions completely covered by vegetation (39.6%) or in burrows dug into soil (36.9%) but the proportions of burrow types differed between sites. Introduced mammalian predators had little or no access to most sites; where predator access was unrestricted, some predator control was usually in place.
In March 1992, we counted southern Buller’s mollymawks Diomedea b. bulleri breeding on the Snares Islands. A total of 7683 occupied nests was counted and a further 777 estimated, giving a total of 8460 breeding pairs. The number of occupied nests counted in 1992 is 78% higher than the number counted in 1969. Although more breeding pairs were present in 1992 than in 1969, with only two counts 23 years apart, it is not possible to determine the current population trend in relation to fisheries activities.
The Chatham Island taiko Pterodroma magentae (Aves: Procellariidae) was rediscovered on 1 January 1978 in its traditional breeding grounds in the Tuku Gully in the south west of main Chatham Island. The history of efforts to rediscover Pterodroma magentae (known as the Magenta petrel) and to identify the mysterious Chatham Island taiko are described. The identity of the Chatham Island taiko and the Magenta petrel is confirmed. Aspects of behaviour, habitat, morphology, and ecology of the species are reviewed. To date, 42 Taiko have been banded; 12 recaptures suggest a population of over 100 birds. Night observations of flying birds and times of burrow use indicate that the breeding season extends from mid-September to mid-May. Efforts to discover the breeding grounds before the assistance of radio telemetry are summarised.
The total population of New Zealand king shag (Leucocarbo carunculatus) was counted for the first time during the 1992 breeding season. At 524 birds, numbers were almost twice as high as estimated previously. The daily rhythm, foraging range and feeding location of king shags from the Duffers Reef colony in the Marlborough Sounds were studied in 1991 and 1992. The mean (± s.d.) foraging range was 8.2 ± 4.1 km (maximum 24 km) from the colony. Most (74%) fed in 31% of the study area, 20-40 metres below the surface on a mainly flat bottom, within the confines of the outer Marlborough Sounds. During the six months courtship/breeding period, daily rhythm of the colony was different from the rest of morning and afternoon. It is assumed that females left to feed in the morning and males in the afternoon to feed and collect nesting material. No double peak was seen during the non breeding period.
The endemic New Zealand shore plover (Thinornis novaeseelandiae) is confined to a small population on Rangatira (South East Island) in the Chatham Islands. There are about 43 breeding pairs and 130 adults. The population is sedentary. Shore plover form monogamous breeding pairs in separate defended territories. Clutch size, parental behaviour, courtship, and defence displays are similar to those of other plovers. Shore plover have several unusual breeding characteristics which may be responses to the relatively constant environment and limited area of habitat on Rangatira, low prey abundance, differences in habitat quality, no mammalian predators, and the presence of certain avian predators. Shore plover are unique among plovers in nesting under cover, which protects their nests from avian predators and temperature extremes, but which would make nests very vulnerable to predation by mammals. Environmental conditions on Rangatira may also be a reason for the high hatching rate, low chick survival, and differing breeding success within the population.