A national census of breeding black-billed gulls (Larus bulleri) conducted across New Zealand in 1995‒98 estimated 48,000 nests, however the methodology used was unclear. In 2013, the New Zealand threat status for the endemic black-billed gulls was changed to Nationally Critical, based on estimates of recruitment failure causing population decline. To inform future threat classification, the breeding population was re-estimated using aerial surveys to locate, photograph, and count breeding black-billed gulls across New Zealand in 2014‒2016. Large spatial gaps in nest count data during 2014/15 and 2015/16 did not allow for annual variability to be taken into account across the 3 seasons, but the 2016/17 survey successfully covered the entire country. Ground counts of nests were conducted at 16 colonies to determine a correction factor of 0.90 to apply to aerial photograph counts of apparently occupied nests. A total of 60,256 nests were found, with 33,703 nests in Southland and 20,675 nests in Canterbury. The North Island was surveyed on the ground and had 992 nests. Historical survey methods were reviewed, highlighting the inaccuracies of using nest densities or applying factors of gulls/nest to total bird counts based on photographs, as well as only counting individual birds on aerial photographs. Historical data likely overestimated numbers of breeding birds, and the inconsistencies of previous surveys make trend analyses difficult. Key recommendations for future counts include: (i) carrying out ground surveys before flights to determine the breeding stage of birds and hence the optimal time to fly; (ii) taking high resolution and zoomed in photos; (iii) carrying out ground nest counts immediately after flights to determine a correction factor; and (iv) using the same observers for all counts to maintain consistency.
Observations of activities of Hutton’s shearwaters at a natural colony in the Kōwhai River and a new colony at Te Rae o Atiu, Kaikōura Peninsula established by translocations were made during the 2014-15 and 2015-16 seasons. Weights and wing lengths of chicks at the 2 colonies taken at comparable times were similar, as were the dates of first emergence and fledging. Thus, adults flying an additional 20 km each way and climbing over 1200 m had no noticeable effect on chick growth at the mountain colony compared to the sea-level colony. Pre-fledging chicks visited other burrows as did adults at both sites, especially at Te Rae o Atiu, where a greater amount of data showed they visited other burrows throughout the season. While some adults stopped visits before fledging, others were still present after chicks had gone. Seven birds that were translocated from the Kōwhai River colony as chicks to Te Rae o Atiu in 2012 and 2013 were recorded at the Kōwhai colony and 2 of these had previously spent 1 night at Te Rae o Atiu; 28 more from the same cohorts were active at Te Rae o Atiu.
Seabird bycatch data collected between 1996 and 2016 in commercial fisheries within the New Zealand Exclusive Economic Zone (EEZ) were analysed to determine if male and female grey petrels (Procellaria cinerea) have different at-sea foraging distributions during the breeding season. Data collection includes the return of bycaught (killed) seabirds from commercial fishing vessels by government fisheries observers. A total of 408 bycaught breeding grey petrels with known sex (214 males, 194 females) were analysed for a locational and seasonal sex bias. Data were also examined to determine whether where carcasses were returned from sea, there were different proportions of males and females captured by different fishing methods: offshore bottom longlining, surface longlining, and offshore trawling. There was no significant difference in the totals of male and female grey petrels returned from fishing operations, but capture locations for the sexes varied widely. More males than females were caught in April, May, August, and September. July showed a reverse trend, while June was the only month with no difference in captures between sexes. More males than females were caught in offshore bottom longliners and trawlers, with the opposite for surface longliners. This study emphasises the importance of a large-scale approach to capture locations and season when analysing impacts of fisheries on seabird populations, and highlights different foraging areas according to sex during the breeding season. Spatial segregation has important management implications as changes in fisheries practice in foraging areas may affect the sex ratio of the grey petrel population.
We assessed the impact of interspecific interactions on the breeding success of the South Georgian diving petrel (Pelecanoides georgicus; SGDP), a Nationally Critical seabird species, by monitoring 20 burrows at Codfish Island (Whenua Hou), with remote cameras. Additionally, we tested the utility of remote cameras to study the breeding biology and activity patterns of the SGDP by pairing 5 remote cameras with RFID readers. We recorded 7 different species at SGDP burrow entrances. The common diving petrel (P. urinatrix) likely caused two monitored burrows to fail. These results suggest that remote cameras are useful tools to study such interactions. However, the cameras had extremely low SGDP detection rates (mean = 10.86%; se = 7.62%) when compared to RFID readers. These low detection rates may be explained by the small body size and the speed at which SGDPs enter/leave burrows. Therefore, remote cameras, or at least the model and setup we used, appear unsuitable to study breeding biology and activity patterns in this seabird species.
We report Records Appraisal Committee (RAC) decisions regarding Unusual Bird Reports received between 1 January 2015 and 31 December 2016. Among the 113 submissions accepted by the RAC were the first New Zealand records of northern fulmar (Fulmarus glacialis), Herald petrel (Pterodroma heraldica), red-footed booby (Sula sula), laughing gull (Larus atricilla) and magpie-lark (Grallina cyanoleuca), the first breeding records for Australian wood duck (Chenonetta jubata) and glossy ibis (Plegadis falcinellus), and the second accepted records of shy mollymawk (Thalassarche cauta cauta), great shearwater (Puffinus gravis) and Cape gannet (Morus capensis). Other notable records included a pair of white-winged black terns (Chlidonias leucopterus) breeding in the Mackenzie basin, and the first record of pukeko (Porphyrio melanotus) from the Snares Islands. In addition, notable influxes of brown booby (Sula leucogaster) and great frigatebird (Fregata minor) occurred during 2015-16.
Museum study-skins are an important though under-utilised resource for studying the biology of endangered birds. This study compares the bill and cere morphology of female and male kākāpō (Strigops habroptilus) from three provenances: 1) “historical wild-origin” museum specimens collected from the North and South islands of New Zealand over 100 years ago; 2) the “modern wild-origin”, predominantly ex-Stewart Island Kākāpō Recovery Programme (KRP) founder population; and 3) the “modern non-wild” descendants of the founder population raised and maintained under the conservation management of the KRP. Bill length and gape was found to be smaller in the historical wild-origin birds than in the two contemporary groups. In comparison, historical wild-origin male kākāpō had larger ceres than both contemporary groups. As bird bills can show rapid morphological adjustment to diet over generational time scales, we evaluate whether bill size differences measured could be due to differences in the nutritional environments experienced by the birds either across their life-times or over recent evolutionary time. We also discuss whether regional variation in sexual selection might account for the provenance related variation in cere size.
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.