Publications Archive

Many aspects of the ecology of the endemic variable oystercatcher (Haematopus unicolor) have not been studied in detail. We colour-banded and monitored a population of the species in a study area between 36°S and 37°S on the east coast of the North Island, New Zealand. Monitoring was intensive during the breeding season from 1994/95 to 1998/99, during which time we gathered information on timing of breeding, chick growth, and productivity. We also recorded measurements of adult birds and eggs. Laying of first clutches was protracted and extended from early September to mid-December. Chicks fledged at lower weights than adults and with shorter total head length and wing, but with tarsus and mid-toe within the adult range. Productivity at four core breeding sites within our study area averaged 0.42 chicks fledged per pair per year. Juveniles commonly remained with their parents on their natal territory during their first winter. From 1999, monitoring was less intensive as we continued collecting data on dispersal, age at first breeding, survival, and pair-bond retention. Natal dispersal values ranged from 0–109 km, with most birds breeding within 60 km of their natal site. As with many oystercatcher species, maturity is delayed, and birds in our study area first bred at between 4 and 8 years of age. There was a high level of mate-fidelity, with one pair-bond lasting 16 consecutive years, but divorce was not uncommon. Once established on a territory, adults were highly sedentary. Annual survival rates of adults and pre-breeders were very high, and the local population had the capacity to grow by about 5% per year. Birds breeding at low-lying sites often lost nests to flooding, and this threat is almost certain to be exacerbated by ongoing climate change.

A total of 15,694 black-billed gulls (tarāpuka, Chroicocephalus bulleri) chicks were banded at six braided gravel-bed rivers in North Canterbury, New Zealand, from 1958 to 1983, and at least 1,754 later sightings of dead or alive birds were reported to the Banding Office. The main banding sites were the Ashley River and its major tributary, the Ōkūkū River; other banding was carried out on the Kowhai River near Kaikoura, Conway River, Waiau River, Waipara River, and Waimakariri River. Colonies typically shifted location between years, as flooding and weed growth affected the habitat and suitability for nesting. Up to 6 colonies were found on the Ashley River system in a season. Average size of all colonies was about 230 nests, with the largest reaching about 800 nests. Some birds were found at rivers apart from their natal rivers. Birds bred when as young as 2-years-old. The furthest sighting was at Firth of Thames, 736 km NE of the banding site; the southernmost was at Waipahi, Otago, 412 km SW of the banding site; and the oldest recovery was 22.1 years after banding. Band loss likely affected recovery rates, as the oldest bird found with an aluminium band was only 10.9 years-old.

Rapa Island, located in Eastern Polynesia, hosts 12 species of breeding seabirds, now primarily found on its ten peripheral islets. These seabirds face various threats, such as invasive mammals that prey on eggs and chicks, as well as invasive plants that encroach upon and degrade their breeding habitats. Major island restoration projects are currently underway on several islets, focusing on the removal of invasive mammals and plants. We present data collected here between 2017 and 2024 and, together with published and unpublished surveys since 1921, compile details on the distribution, population, and breeding seasons of these seabird species.

Te Araroa Trail runs for more than 3,200 km between Cape Reinga and Bluff, along the length of Aotearoa New Zealand’s two main islands. All birds seen and heard along the trail during the austral summer were counted in 1,720 contiguous transects during 124 days of walking from north to south between 2 November 2023 and 11 March 2024 (84.7% of transects were 2 km long). A total of 106,207 birds of 107 species were counted during daylight transects, at a mean encounter rate of 32.6 individuals per km. The highest counts were for house sparrow (Passer domesticus – 12,517 birds), chaffinch (Fringilla coelebs – 5,806), and red-billed gull (Chroicocephalus novaehollandiae – 5,427). The species recorded most frequently were chaffinch (62.3% of transects), silvereye (Zosterops lateralis – 58.5%), and Eurasian blackbird (Turdus merula – 56.7%). Bird communities are summarised and compared for 19 sections covering the entirety of the trail, providing a baseline for comparisons within regions and over time. Northern and/or southern limits are presented for 30 species with restricted distributions. Comparison of counts along sections of the trail that were trapped (233 km, including 22.4% of forest) with counts from untrapped forest sections revealed that tūī (Prosthemadera novaeseelandiae), kererū (Hemiphaga novaeseelandiae), and New Zealand fantails (Rhipidura fuliginosa) were more abundant where predator control was undertaken. Twenty of the fantails seen in the South Island were black morph (5.6%), with the remaining 339 (94.4%) pied morph, indicating that the proportion of black morph birds has been stable over the past two decades. In addition to describing bird communities likely to be encountered on different sections of Te Araroa Trail, this account (and the dataset it is based on) provides a baseline for comparing New Zealand bird communities over time and space.

A collection of 16 birds from Hokianga, including the type specimens of banded rail Hypotaenidia philippensis assimilis and black petrel Procellaria parkinsoni, is recorded as presented to the British Museum in 1842 by a mysterious “Miss Rebecca Stone.” She is identified as Rebecca Stones of London, who presented birds brought from Hokianga by her brother William Stones. A further search for the collector in Hokianga, based on the evidence of the specimens and how they were obtained, prepared and documented, points to the Wesleyan missionary William White, and also reveals much about the practices of ornithology of the time. It also reveals that Hokianga Māori, notably Mohi Tāwhai of Waimā, played a significant role in obtaining and naming birds for the collection. The type localities for New Zealand banded rail, black petrel, and Botaurus melanotus are restricted to Hokianga, Northland.

The Auckland Domain is the city’s oldest park and contains over 70 ha of contiguous, mature urban forest. Five-minute bird counts were made across one year within the domain forest in 2019 and 2020 and compared with counts conducted in 1987 and 1988, using the same methods and at the same survey sites, to investigate changes in the structure of the urban bird community. The abundance and species richness of native and introduced birds increased between the count years and there was structural change within the community driven by increases in the abundance of forest-adapted endemic species, tūī Prosthemadera novaeseelandiae, grey warbler Gerygone igata, and kererū Hemiphaga novaeseelandiae, and declines in generalist native species, silvereye Zosterops lateralis and fantail Rhipidura fuliginosa. Tūī showed the most profound increase in abundance between count years, reflecting regional conservation management of mainland and island forest habitats that benefit this highly mobile species. Increased abundance of eastern rosella Platycercus eximius and common myna Acridotheres tristis also altered community structure between count years, indicative of ongoing colonisation by these exotic species in the Auckland region since their introduction to the North Island. The fact that both these species compete with native taxa for nest cavities within forests is of concern. Our results reinforce the need to manage and protect maturing urban forests to enhance native bird populations. Such actions will also support the recovery of native bird populations at a landscape scale.

Egg floatation is a technique which can be used to estimate egg age and hatching dates of New Zealand shorebird eggs. It can be used to improve the accuracy of nest survival models, help identify nest outcomes, assist with chick survival monitoring and to prioritise the capture of incubating birds. We used egg floatation to estimate the age and hatching dates of South Island pied oystercatcher (Haematopus finschi) (SIPO) eggs. We developed regression equations to estimate the age of SIPO eggs by modelling egg angle and egg float height against egg age using a sample of eggs with known hatch dates. For early incubation eggs, we used linear regression to model the relationship between egg age and egg angle only, whereas for late incubation eggs we used multiple regression to model the relationship between egg age and both egg angle and egg float height data. These equations allowed 90% of SIPO eggs to be aged to within five days of their actual age. We recommend that species-specific regression equations describing the relationship between egg float characteristics and egg age be developed for other New Zealand shorebird species, to aid future research, monitoring and conservation management actions on these species.

Abstract: Observations were made of the Nationally Vulnerable Hutton’s shearwater (Puffinus huttoni) breeding at Te Rae o Atiu, Kaikōura Peninsula (42.429°S, 173.703°E), New Zealand, a new colony established by translocations where birds breed in nestboxes. Over 12 seasons there were 245 eggs laid, including seven instances of two eggs laid as separate clutches in one nestbox during the same season. Nestbox inspections, usually undertaken weekly, provided evidence of egg laying date. Bird attendance at the nestboxes was also obtained from implanted passive integrated transponders that triggered a reader and datalogger. There is evidence for birds re-laying an egg after the first egg failed for three separate events, and a fourth was a possibility. In three other events, it appears more likely that two different birds laid the eggs, two as female-female pairings or simply egg dumping by an unpaired female; the third event was inconclusive. Only one of the 14 eggs from two-egg nests hatched, and the chick fledged successfully, about 10 days later than any other chick recorded at this colony. This fledging date was similar to the last date for fallout birds from the natural, mountain colonies, and suggests that re-laying may be a natural consequence of early egg failures in this species.

Since the publication of the fifth edition of the Checklist of the Birds of New Zealand in 2022, 3 new vagrant species (2 terns and a storm petrel) have been accepted as occurring in New Zealand as at 31 December 2023, and 11 species that became extinct more than c. 1 million years ago have been described. These comprised 3 waterfowl, 1 owlet-nightjar, 1 tropicbird, 3 penguins, 1 albatross, 1 petrel, and a ‘false-colie’ (the latter is considered unrelated to any known group of birds). These 11 new fossil species were found in deposits of the following epochs: Paleocene (3), Miocene (6), and Pliocene (2). The richest areas for discovering new species were Miocene lacustrine deposits of the St Bathans region of Central Otago (5 species), and Paleocene marine deposits from the eastern South Island (3 species). Two Pliocene seabirds were from marine sediments in south Taranaki, and a Miocene albatross was found in a limestone quarry in South Canterbury. Recent publications potentially affecting the taxonomy, nomenclature, classification and arrangement of New Zealand birds are assessed, and recommendations are made that affect 56 taxa. This includes splitting Tibetan sand plover Anarhynchus atrifrons from Siberian sand plover A. mongolus, and Pyramid prion Pachyptila pyramidalis from fulmar prion P. crassirostris, thereby adding a further two species to the New Zealand bird list. The total number of bird species, including fossil species, now accepted from the New Zealand region is 502.

The wrybill | ngutu pare (Anarhynchus frontalis) is a small plover endemic to New Zealand with a unique laterally curved bill. Apart from moult, much of its biology is well understood: adults breed from late August to January on the braided river systems in Canterbury and inland Otago on New Zealand’s South Island. From midsummer, late December and January, they migrate north to non-breeding areas in the northern part of the North Island, especially to the large tidal bays, east and west of Auckland, where they undergo primary moult from January to April. The Underhill- Zucchini moult model was used to estimate the mean start and completion dates of primary moult, which were 20 January and 3 April respectively. Adults thus commence primary moult soon after arrival on non-breeding grounds but complete moult around four months before southward migration to their breeding areas in August. They appear to avoid primary moult during winter. Second-year birds start primary moult in December, one month earlier than the adults, but finish at approximately the same time. Primary moult of the wrybill is compared with closely related species, and with other waders that breed on the South Island and migrate to North Island for the non-breeding season.