Breeding success of the endemic black-fronted tern (Chlidonias albostriatus) and the identity of predators was studied in the upper Clarence and Acheron Rivers (Molesworth Recreation Reserve), South Island, New Zealand in the 2012, 2013 and 2014 breeding seasons. The catchment supports a nationally and therefore internationally significant population of over 720 breeding birds. A combined total of 1,510 nests were monitored over 3 seasons. Breeding success was poor with only 42.7% of nests hatching at least 1 egg, and average productivity of only 0.13 chicks fledged/nest. Breeding success varied between years and rivers, primarily due to differing predation rates. Predation and nest abandonment following nocturnal predator disturbance were the primary causes of nest failure. A total of 110 filmed predation events at nests identified ferret (Mustela furo), feral cat (Felis catus) and hedgehog (Erinaceus europaeus) as the main predators. Following a beech and tussock masting event, predation by ship rats (Rattus rattus) was significant in 2014. This is the first time predator increases following mast seeding has been shown to impact braided river birds. In contrast, avian predation was low and varied across rivers. Productivity was higher in large colonies (>25 nests) than small colonies, and in early colonies (colony formation before 31 October). A management programme to improve black-fronted tern productivity has been initiated given the national importance of this population, the ease of access to these colonies, and the identification of the invasive predators responsible for current levels of poor breeding success.
The risk of disorientation by artificial lights and subsequent ‘fallout’ has become a widely recognised issue for nocturnal procellariiform species. Using data from community-based rescue campaigns and systematic research, we assessed the characteristics of fallout events observed in fledglings of the threatened New Zealand endemic Hutton’s shearwater (Puffinus huttoni) or Kaikōura tītī. Despite strong annual variation in observed fallout numbers, the proportion of annually produced fledglings collected as ‘fallout birds’ remained below 1% each year. Among those, more than 80% survived due to community rescue efforts. Fallout was found to increase significantly during new moon, while weather effects remained inconclusive. Most fallout occurred within brightly lit areas of Kaikōura township, particularly along its coastal roads. High light source densities and high wattage lights appeared to be influential in some areas but could only partly explain the spatial distribution of fallout at this small scale.
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.
The black petrel (Procellaria parkinsoni) is recognised as the seabird species at greatest risk from commercial fishing activity within New Zealand fisheries waters. Despite the fact that valuable mitigation information could be obtained from such data, little is known about the diving ability of this species. Diving data were obtained from electronic time–depth recorders from 22 black petrels breeding on Great Barrier Island (Aotea), Hauraki Gulf, New Zealand, during the early chick rearing period from January-February in both 2013 and 2014. This paper presents the first information on the diving ability of black petrels. The deepest dive recorded was 34.3 m, but maximum dive depths varied considerably among individuals (range 0.8-34.3 m). The majority (86.8%) of all dives were < 5 m and black petrels rarely dived to depths of >10 m. The majority (92.7%) of dives were during the day and time of day had no major effect on dive depth. Only males dived at night, between 2300 and 0200 hours. This information could be used to improve mitigation measures for black petrel and other seabird bycatch in longline fisheries particularly in relation to recommended depths for unprotected hooks and line sink rates. To achieve the recommended minimum 10 m depth for unprotected hooks it has been shown that hooks have to be deployed at 6 knots with a 0.3 m/second line sink rate when using 100 m streamer lines. Adoption of these measures should further reduce black petrel bycatch in longline fisheries.
Many bird species have been successfully introduced beyond their natural range, some becoming more abundant in their new environment than in their country of origin. In this study, bird density was measured at 2 study areas comprising a total of 48 recreational parks in northern England and Canterbury, New Zealand, for 10 focal species (native to the former, introduced to the latter). Site characteristics and presence of other bird species were also recorded and investigated as potential explanatory factors for differences in density between the 2 study areas. Common redpoll, common starling, European greenfinch and house sparrow had significantly higher densities at the New Zealand sites. Analysis using generalised linear models revealed a negative relationship between common starling density and proportion cover of trees and shrubs, and a positive relationship between common redpoll, common starling and European greenfinch densities and site species richness. However, since there were no significant differences in site characteristics or site species richness between study areas, these relationships could not account for higher densities at the New Zealand sites. There was an apparent negative relationship between densities of common starling and house sparrow and foraging guild diversity, suggesting that interspecific competition may contribute to differences in density between study areas. The proportion of variation explained by the models was relatively low, suggesting that there may have been missing variables that influenced species density. More detailed study of a wider range of variables is required to investigate this further.
Nocturnal surveys for collared petrel (Pterodroma brevipes) indicate significant variation in the number of birds reported by site, time of year, and survey method. Collared petrels were recorded at 3 new islands within Fiji in 2011. These records indicate that locating collared petrels requires focussed survey effort, although they do not definitively confirm breeding on the islands, for which ground-based searches would be required. When visiting sites where there has been no recent evidence of collared petrel breeding, surveys should be undertaken between February and April (at the start of the breeding season), should use an active method of survey comprising both light for attraction and playback and/or with ‘war whooping’, and should be repeated at a number of sites before concluding that an island holds no breeding birds.
Orange-fronted (Cyanoramphus malherbi) and yellow-crowned parakeets (C. auriceps) are sympatric congeners that are secondary cavity nesting species, with the former being critically endangered. Both currently inhabit anthropogenically-modified Nothofagus forest. We compared the characteristics of nest sites in both species and found the majority of nest site parameters (tree height, height of hole above ground, DBH, tree condition and aspect) were similar. However, orange-fronted parakeets selected nest cavities with a significantly narrower entrance, and when situated in red beech (Nothofagus fusca), nest entrances were significantly smaller in area than in yellow-crowned parakeets. As the male orange-fronted parakeet is smaller in body mass than the male yellow-crowned parakeet (only males feed nestlings when laying multiple clutches), the difference in nest hole size may simply indicate that they are capable of utilising smaller entrances. We also found that orange-fronted parakeets selected nest holes in standing dead trees more frequently and nest sites in silver beech (N. menziesii) less frequently than expected. While the lack of differences in nest site characteristics suggests some interspecific competition may be occurring between these species (i.e., they occasionally use the same nest holes), it is difficult to establish this experimentally and to determine whether these differences are artefacts of former niche separation in unmodified forest.