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.
Discriminant function analysis (DFA) is widely used to determine sex in the field from morphological measurements of bird species with monomorphic plumage. Sexual dimorphism was examined in black petrels (Procellaria parkinsoni) using 7 external measurements of adult birds breeding on Great Barrier Island, New Zealand. Males were significantly larger than females in absolute values of all measurements except for tarsus. Two stepwise DFA models were developed. The first used all 7 parameters, while the second model used only 6 parameters in order to increase sample size. Model one and two showed an 88 and 82% classification success, respectively, most likely due to the high overlap in measurements between males and females. These canonical functions were not accurate enough for field surveys, but may be improved using a larger and more representative sample size.
Flesh-footed shearwaters (Puffinus carneipes) are considered to be one of New Zealand’s seabird species that is most heavily impacted by both commercial and recreational fisheries, yet they have an IUCN ranking of “Least Concern”. To resolve this contradiction we conducted surveys on 3 large breeding colonies and compared our results to historical data. We found that the burrow density on the most northerly island (Lady Alice Island/Mauimua) has increased since the last set of surveys; however the density of flesh-footed shearwaters nests has remained stable. At the largest colony we surveyed (Ohinau Island), the density of burrows has remained stable, while the density of nests has declined. At New Zealand’s most southerly colony (Titi Island), both burrow and nest densities have remained stable. Our results suggest that the status of flesh-footed shearwaters populations in New Zealand is variable with 2 populations that are stable and 1 that is declining. Nevertheless, due to the short time period between our surveys and the historical data, repeated surveys in the future are needed to determine if further declines in the largest colony warrant a reassessment of the status of this species.
Of 4 importations of Canada goose Branta canadensis into New Zealand, 2 (in 1905, 1920) resulted in breeding. Commencing in 1907, multiple and repeated releases of the 1905 geese and their progeny had, by 1922, established flocks of several hundred distributed along the eastern Canterbury and Otago foothills of the Southern Alps. Thereafter, the geese spread widely but remained resident and breeding only in the South Island. Establishment of Canada geese in North Island commenced in 1969 with the first of 4 transfers by the Wildlife Service, collectively totalling 280 birds from Canterbury’s Lakes Ellesmere and Forsyth, to coastal Wairoa lakes and nearby locations. The Wildlife Service assisted numerous other transfer and release initiatives, of at least 800 birds, in North Island in the 1970s and 1980s, principally by Wellington and Auckland Acclimatisation Societies, Ducks Unlimited, and private waterfowl enthusiasts. At the same time it supported transfers of 450 geese to the South Island’s West Coast. From these multiple releases Canada geese have become widespread in rural New Zealand.
Kiwi (Apteryx spp.) are the most vocal of the ratites. Of the 5 Apteryx species only 2 have previously been subject to detailed vocal analysis: the North Island brown kiwi (A. mantelli) and the little spotted kiwi (A. owenii). This paper describes the vocalisations of the great spotted kiwi (A. haastii), the largest of the Apteryx species. Acoustic recorders were installed near the breeding den sites of 7 great spotted kiwi pairs residing in Hawdon Valley, Canterbury between November 2012 and March 2013. A total of 133 whistle vocalisations from 10 individuals were subject to detailed temporal and spectral analysis. Male and female syllables were found to be sexually dimorphic; syllables in male calls tended to be longer and more highly pitched than their female counterparts. Despite this dimorphism, patterns of intra-call variation were consistent between the sexes. It appears that intra-call variation is a trait which varies markedly within the Apteryx genus.
Prior to 1992 the total population of New Zealand king shag (Leucocarbo carunculatus) was estimated to be about 300 individuals. Between 1992 and 2002, colonies in the outer Marlborough Sounds, New Zealand were surveyed by boat and the total population was estimated to be 645 birds. About 92% of all birds occurred at Duffers Reef, North Trio Island, Sentinel Rock, and White Rocks, with an estimated 102-126 breeding pairs. A survey in February 2015 was the first to be conducted from the air. All colonies were photographed within 44 minutes prior to the morning departure and the total population was estimated to be 839 individuals. A total of 187 pairs/nests were recorded using aerial 3D images of all breeding colonies in June 2015. North Trio Island was the largest breeding colony with 33.7% of all nests, followed by Duffers Reef with 18.7% of all nests. Despite the larger revised population size, the species remains Nationally Endangered.