Abstract: We report Records Appraisal Committee (RAC) decisions regarding Unusual Bird Reports received between 1 January 2023 and 31 December 2024. Among the 195 submissions accepted by the RAC were the first New Zealand records of Horsfield’s bronze-cuckoo (Chrysococcyx basalis), MacGillivray’s prion (Pachyptila macgillivrayi), and the Asian subspecies of gull-billed tern (Gelochelidon nilotica affinis). We also report the second accepted records of stilt sandpiper (Calidris himantopus), Bulwer’s petrel (Bulweria bulwerii), and dusky woodswallow (Artamus personatus), the third accepted sighting of northern pintail (Anas acuta), and the second and third accepted records of streaked shearwater (Calonectris leucomelas). Other notable records included the first records of Kermadec petrel (Pterodroma neglecta) and brown booby (Sula leucogaster) at Rēkohu/Wharekauri/Chatham Islands, plumed whistling duck (Dendrocygna eytoni) at the Snares Islands/Tini Heke, Canada goose (Branta canadensis) and black shag (Phalacrocorax carbo) at Antipodes Island/Moutere Mahue, and fork-tailed swift (Apus pacificus) and tree martin (Petrochelidon nigricans) at the Auckland Islands/Motu Maha. We also clarify the dates of occurrence of the first vagrant lesser frigatebird (Fregata ariel), Australian pelican (Pelecanus conspicillatus), and black-faced cuckoo-shrike (Coracina novaehollandiae), all recorded from New Zealand before 1900.
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.
Shorebird nest outcomes can be affected by factors such as predation, human disturbance, and habitat characteristics. Over two breeding seasons between 2022–2024, we monitored the hatching success of banded dotterels (Anarhynchus bicinctus), southern black-backed gulls (SBBGs) (Larus dominicanus), black-fronted terns (Chlidonias albostriatus), pied stilts (Himantopus leucocephalus), and variable oystercatchers (Haematopus unicolor) at the Ashley River estuary, New Zealand, and compared these values to those in the literature. We also recorded habitat variables at the nest sites of the two species with the largest sample sizes: banded dotterels and SBBGs. Hatching success was lowest for black-fronted terns and highest for SBBGs. Overall, failure was predominantly due to predation and flooding. SBBG hatching success was unrelated to the measured nest site variables but may have been influenced by seasonal changes, with earlier nests appearing more successful. Banded dotterel nests that were closer to water appeared to be more successful, as did nests in the first year of the study. Cats (Felis domesticus) were recorded depredating banded dotterel nests, highlighting the importance of monitoring and controlling invasive species to protect native birds in New Zealand’s estuaries.
Abstract: Life history and ecological characteristics of extant mergansers (Tribe Mergini) are summarised and used to infer those likely displayed by the extinct merganser from “mainland” New Zealand (Mergus sp. indeterm.). I speculate this was a river-dwelling species, plausibly a year-round territorial occupant of mid-lower reaches of rivers, whose subadults and non-breeders may have aggregated seasonally on broad lower reaches, including estuaries. Of extant mergansers, its ecology was probably most similar to that of Brazilian merganser (Mergus octosetaceus). Holocene sea-level rise and loss of habitat may have induced changes in social structure of Chatham Island merganser. A plausible life history and ecological template, however speculative, can aid evaluations arising from other sources of evidence e.g. locations of fossils and bone stable isotope chemistry.
Holdaway, R.N.; Allentoft, M. E. 2022. A basic statistical approach to determining adult sex ratios of moa (Aves: Dinornithiformes) from sample series, with potential regional and depositional biases. Notornis 69: 158-173.