Change in the relative abundance of grey duck (Anas superciliosa) and mallard (A. platyrhynchos) in New Zealand, from 1950 to the present day, is summarised from trapping records, hunters’ kills, and field studies. Mallards achieved numerical ascendency over grey duck throughout most of New Zealand by the late 1970s, merely 20 years after the cessation of mallard releases by historic acclimatisation societies. Post-1990, the relative abundance of mallard in almost all districts, as recorded from hunters’ kills, appears to have stabilised at 90%, or higher. Uncertainty about hunters’ and the public’s ability to discriminate between grey ducks, their hybrids with mallard, and variably-plumaged mallard females is demonstrated and most modern (post-1990) records of relative species abundance must be regarded as quantitatively suspect. Ducks identified as grey ducks by hunters are now a relative rarity throughout New Zealand, except in Northland and West Coast. Post-1990 duck trapping in North Island indicates that grey ducks, where reported, are patchily rather than generally distributed. The absence of genetically-validated criteria for discriminating ducks of grey duck x mallard hybrid ancestry continues to confound field identifications of both species.
I recorded the calling behaviours of shining cuckoos (Chrysococcyx lucidus) from 1992 – 2015 on Kawau Island. The 3 most common calls, the upward crescendo “whistling call,” the downward slur “call-note,” and the “call-note” with “chatter” notes, were given from the arrival of adults in late August-early September until early January. After January only the call-note was heard. The upward whistling calls averaged 9.5 notes per calling bout (se = 0.18, n = 721). There was no significant difference in the number of whistling notes given with or without following notes. Single call-notes from lone cuckoos or groups of birds were restricted to specific sites on ridges. Calling was infrequently heard during evening twilight, and not heard during darkness. There was an increase in the number of cuckoo detections after 2009, and this corresponded with the appearance of communal behaviour and calling.
The valley of the South Branch of the Hurunui River, prior to 2001, held a dense population of the orange-fronted parakeet (Cyanoramphus malherbi). However, a rat plague in 2001 reduced this population by ~85%. In preparation for a restoration program of this species in the Hurunui valley, I analysed the distribution of sightings of orange-fronted parakeets, as well as the congeneric, yellow-crowned parakeet (C. auriceps) prior to the population collapse. My objective was to identify the areas and types of habitats used by each species. A vegetation survey showed significant differences between different parts of the valley floor study site, and this appeared to be reflected in the distribution of orange-fronted parakeets. Both species had significantly different distributions, and orange-fronted parakeets were recorded most frequently within forests growing on the river fan, an area characterised by mature red beech (Nothofagus fusca) and areas of dense regenerating mountain beech (N. solandri var. cliffortioides). While the valley has been subject to anthropogenic modification since the 1850’s, it still contains a relatively intact beech forest. My observations on the historic distribution of orange-fronted parakeets suggest this valley is still capable of supporting a large population of the species. However, the success of any re-introduction program is likely to depend upon continued preventative and reactive predator control, as well as a release programme that introduces enough individuals to prevent severe bottlenecks.
The breeding behaviour and development of New Zealand falcons (Falco novaeseelandiae) were recorded at 2 nests in Kaingaroa Forest during a 4-month period up to 2 March 2007. This covered the later part of incubation, and the entire nestling and early post-fledging periods. Incubation was shared between parents; the male primarily incubated the eggs, during which time the female hunted. The male only provided occasional prey for the female. Brooding by both parents was intensive for the first 6 days and then gradually declined until the chicks reached 14 days old at which point it ceased. Assisted feeding of the chicks was almost always undertaken by the female. The male’s primary role during the nestling period was prey delivery. During the early nestling period the female spent the majority of the time brooding chicks before shifting to hunting for the young.
We collated and reviewed 4179 records of the historic and contemporary distribution of the endangered specialist wetland bird, the Australasian bittern (matuku, Botaurus poiciloptilus), in New Zealand, to assess its current status and trends in its distribution across major habitat types. We mapped distribution in 5 time periods (pre-1900, 1900−1949, 1950−1969, 1970−1989, post-1990). We found that Australasian bittern are currently found throughout New Zealand with strongholds in Waikato, Northland and Auckland regions (46% of records) in the North Island, and Canterbury and West Coast (22%) in the South Island. They occur widely in freshwater and brackish riverine, estuarine, palustrine and lacustrine habitats. Australasian bittern were abundant (records of groups >100 birds) in Māori and early European times, but historical maps indicate their range appears to have been reduced by c. 50% over the last hundred years, with the most dramatic shrinkage in range occurring post-1970. Marked declines in occupancy began in Otago, Canterbury, Waikato, Wellington and Auckland regions between the 1900-1949 and 1950-1969 periods and reductions in range have been steady since. In comparison, declines in Northland, Southland, West Coast and Tasman/Nelson appear to be more recent and greatest between the 1970-1989 and post-1990 periods. The apparent shrinkage in range is supported by numerous observations in the literature. Australasian bittern distribution is now biased towards coastal areas and lowland wetlands of the North Island. Information indicates that range reductions were paralleled by marked declines in numbers: 34% of pre-1900 records were >1 bittern and 7.3% were >10, whereas post-1990, only 19% of records were >1 and 0.7% >10. The clearance and drainage of wetlands (c. 90% loss) and shooting were major causes of declines, but contemporary threats include continued habitat loss and degradation, accidental deaths from a range of causes, and predation by introduced mammals. Current trends in Australasian bittern populations suggest that they should be reclassified as Nationally Critical under the New Zealand threat classification system. Conservation management should focus on restoration of hydrology, water quality and aquatic food supplies, predator control, reedbed management and maintaining regional wetland networks.
Eight species of nationally declining river birds currently breed on the Ashley River, less than 1 km from the townships of Rangiora, Ashley, and Waikuku Beach. Threats to their breeding include human interference, mammalian predation, and vegetation encroachment in the riverbed. The numbers of at least 3 of these species appear to have declined from 1963 to 2000, in line with national trends. In 2000, a Rivercare Group commenced a public awareness campaign about the plight of the birds, trapping introduced predators, and clearing vegetation in parts of the riverbed. Annual surveys from 2000 to 2015 show a significant increase in numbers of banded dotterel (Charadrius bicinctus), wrybill (Anarhynchus frontalis), black-fronted tern (Chlidonias albostriatus), and pied stilt (Himantopus himantopus). Numbers of the other 4 species, including black-billed gull (Larus bulleri), the most threatened, have not changed significantly, in contrast to declining national trends. We suggest the Rivercare Group’s management actions have contributed to these successes, and support continuation of their actions.
Waterbirds were counted over ~ 12 ha of Western Springs Lakeside Park, Auckland, twice-monthly from November 2012 to October 2014. On average there were 742 water-birds per count (s.d. = 151.7, range = 511–1081), equating to a mean density of about 62 birds/ha within the study area. The 3 commonest species (mallard, Anas platyrhynchos, black-backed gull, Larus dominicanus and feral goose, Anser anser) made up 63% of all waterbirds counted. Mallard (and all waterbirds combined) were most abundant in summer and autumn. Black-backed gull, Eurasian coot (Fulica atra) and New Zealand scaup (Aythya novaeseelandiae) were seasonally uniform in numbers but red-billed gull (Larus novaehollandiae) were virtually absent from September to December. Spring was the peak season for numbers of black swan (Cygnus atratus), but the seasonal minimum for feral geese. Incidental historical counts trace temporal changes at Western Springs Lake, with a rapid increase of coots in the 1980s and of scaup in the 1990s. Royal spoonbill (Platalea regia) arrived more recently. The counts quantify for the first time the importance of the lake as a habitat for common water-birds on the Auckland isthmus.
The use of DNA barcodes (haplotypic variation in a 648 bp segment of the cytochrome c oxidase subunit I [COI] gene within the mitochondrial genome, starting from base 58 at the 5’ end of the gene) as part of a species description is an accepted part of modern taxonomy. The evidence COI provides is compelling since a sequence of DNA is biological data obtained from living material. Early in the use of COI, it became apparent that it might highlight potential cryptic species and inform the debate around their status. The little penguin (Eudyptula minor) has been the subject of such debate. DNA barcodes from 53 little penguins were assessed to determine the specific status of this species across its range. Analysis of these data indicates distinct Australian and New Zealand haplotypes that may be indicative of separation at the species level. The specific status for the 2 populations is also supported by behavioural evidence and geographic isolation.
Gould’s petrel, Pterodroma leucoptera, comprises 2 subspecies: P. l. leucoptera that breeds in eastern Australia, and P. l. caledonica that breeds in New Caledonia. The latter subspecies was diagnosed primarily on the basis of plumage differences observed between beachcast specimens from New Zealand (presumed to be P. l. caledonica) and a small sample of specimens from Cabbage Tree Island in Australia. This study re-examined the diagnosis of P. l. caledonica by quantifying plumage variation in both subspecies using live individuals and museum specimens originating from breeding colonies. Variation in supposedly diagnostic plumage characters within the larger sample of the nominate subspecies encompassed almost the entire variation observed in P. l. caledonica; though the former tended to be more heavily pigmented. Given the lack of valid diagnostic characters, the retention of P. l. caledonica as a distinct taxon is difficult to justify. Gould’s petrel should therefore be treated as monotypic.
Many globally threatened bird species have been shown to have highly male-skewed sex ratios. This is concerning for conservation as such populations have a higher extinction risk and lower reproductive population sizes. Our surveys of the remaining populations of orange-fronted parakeet (Cyanoramphus malherbi) indicate this species currently has a non-breeding season adult male population proportion of between 0.56 and 0.66. This male bias increased to between 0.68 and 0.74 during the breeding season. Limited data also suggest that prior to recent declines in the population size of orange-fronted parakeets, driven largely by introduced mammalian predators, the adult sex ratio (ASR) may have been closer to parity. The excess of males indicates that this species currently has a compromised population structure, despite intensive conservation management undertaken since 2000 to limit predation.