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.
Abstract: Tree martins (Petrochelidon nigricans) are vagrants to New Zealand from Australia, with the first record in 1851. However, there is some doubt as to whether every tree martin historical record can be assigned to this species, with the now-established welcome swallow (Hirundo neoxena) a likely confusion species. Records of tree martins and other hirundines were examined against historical record criteria in order to establish an accurate picture of past tree martin vagrancy. Forty-eight relevant records (1851–1978) were collated and reviewed. It was considered that 16 records were probable or confirmed tree martins, 19 were possible tree martins, and just three were possible welcome swallows. The remaining ten records were classified as unidentifiable, with most of these lacking descriptions. Only four 19th century tree martin records should be verified. None of the many 1892–93 hirundine invasion records could be certainly assigned to any particular species. Considering the tree martin was more frequently recorded, it is perhaps surprising it is the less successful colonist of the two species.
Abstract: The black-winged petrel (Pterodroma nigripennis) is an abundant procellariiform seabird breeding on islands in the Southwest Pacific and Indian Oceans. The largest populations breed in the New Zealand region where at sea movements and breeding behaviour across the annual cycle remain poorly described. We used geolocators with saltwater immersion sensors to track movements and characterise breeding behaviour of P. nigripennis from three New Zealand breeding colonies (Raoul, Burgess, and Rangatira Islands) across a 1,600 km latitudinal gradient. Breeding extended from November to June and in Raoul Island birds pre-laying, incubation, and chick rearing periods lasted 36, 50, and 85 days respectively. During breeding, birds from all colonies foraged within waters of the subtropical convergence zone which for Raoul, required one-way foraging trips of over 1,500 km. During March–June birds migrated east, then north and northwest to core foraging zones predominantly within the North Pacific subtropical front, but a small number of birds also wintered south of Hawaii in equatorial waters. Birds were predominantly nocturnally active during breeding and non-breeding seasons indicating a dependence of nocturnally available prey. These data contribute to a growing understanding of the unprecedented movements and potential partitioning of habitat by Australasian Pterodroma petrels within the Pacific Ocean and we summarise and discuss available data.