Publications Archive

Accounts of magpie Gymnorhina tibicen attacks on birds in New Zealand were collated from literature and a survey of the public, and then summarised to identify the frequency and characteristics of reported attacks on different species. Magpies were reported attacking 45 bird species. Species commonly found in rural habitats (e.g., harrier hawk Circus approximans, blackbird Turdus merula) where magpies are abundant were attacked most; however, a directly proportional relationship between species abundance in rural habitats and reported attack frequency did not occur. Species consuming similar foods to magpie tended to be attacked more often, probably because these foods are more abundant in rural areas. Attacks on smaller birds (e.g., grey warbler Gerygone igata) regularly (66%) resulted in death, but deaths declined as victim weight increased. Non-contact attacks were most common for the largest species (e.g., kereru Hemiphaga novaeseelandiae). Non-contact and non-lethal contact attacks occurred throughout the year while attacks resulting in death occurred mainly during the magpie’s breeding season (July to November). This study indicates that magpies can attack a wide range of species but fails to determine why (no one explanation satisfies all cases). Limitations of the dataset and future research to control these are discussed.

We analysed 13C and 15N isotopic enrichment in Australasian harrier (Circus approximans) eggshell and two discarded harrier feathers from Motunau Island, a regionally important seabird breeding island. Among the prey remains found at the nest was a prion (Pachyptila sp.) wing fragment and a predated blue penguin (Eudyptula minor). We combined isotope data from the prey remains, plus potential prey items obtained from the mainland, to reconstruct harrier diet and evaluate incorporation of seabird nutrients. During egg material formation, blue penguins made up a major part of the female harrier’s diet. During autumn, when feathers were re-growing, the two feathers (which may or may not have been from different individuals) gave very different results. The feather with the more marine signature was growing when harrier diet included a significant proportion of blue penguin and/or fairy prion (Pachyptila turtur) material. Formation of the other feather may have occurred while harrier diet was primarily terrestrial. Our results are indicative of the usefulness of stable isotopic analysis in elucidating nutrient flows and contributions to animal diet.

A survey was undertaken in the Te Waiiti Stream, Bay of Plenty, in summer 2002/2003, to identify blue duck (Hymenolaimus malacorhynchos) roost habitat. Thirty-six roosts were identifi ed along 18.5 km of stream channel, averaging three roosts per blue duck pair. Stable undercut banks were most commonly used as roost sites (42%), followed by log jams along stream banks (25%). Large woody debris (LWD) was a component of 50% of the roost sites, and there was a positive relationship between LWD loadings in the stream channel and number of LWD roosts. All roosts provided overhead and lateral cover, most likely an adaptive response to current and historic avian predators, and all were located at the water’s edge. The location and composition of roosts provided easy access to the stream channel, discrete cover for rearing juveniles and for moulting, and daytime shelter. There were indications that channel morphology characteristics in the lower section of the survey reach may be limiting roost habitat availability and blue duck occupancy. Suitable roost habitat is a year-round requirement for blue duck and should be considered when evaluating their habitat.

We observed black and white-plumaged storm petrels on 27 seabird-watching trips to the outer Hauraki Gulf, New Zealand, November 2003 – June 2005. We studied their plumage characteristics, behaviour and seasonal occurrence: the birds had common plumage characteristics and sightings of them were concentrated in the outer Hauraki Gulf from October to March and further offshore in April-May. Their presence in the Hauraki Gulf coincided with summer breeding of other seabirds, in particular white-faced storm petrels (Pelagodroma marina). Their pattern of occurrence off northern New Zealand suggests the birds may be breeding in the Hauraki Gulf; the Mokohinau Islands, rid of rats (Rattus exulans) 15 years ago, is a potential breeding site In our view these black and white storm petrels do not conform to descriptions of any extant species known from New Zealand waters, and, consequently, we speculate that our observations may have been of New Zealand storm petrels (Pealeornis maoriana Mathews 1932), a species known from only three specimens collected in the 19th century.

We describe and name a new subspecies of fulmar prion as Pachyptila crassirostris fl emingi. This little-known seabird has less than 1,000 pairs breeding at the Auckland Islands and 1,000-10,000 pairs breeding on Heard Island. It is probably largely sedentary around these islands in winter, with possible stragglers reaching mainland New Zealand and Tasmania.

35,289 southern royal albatrosses (Diomedea epomophora) were banded on Campbell Island between 1941 and 1998, including 24,258 chicks and 11,031 adults. By 2003, 240 (0.68%) band recoveries and live recaptures away from Campbell Island had been reported. Birds banded as chicks were reported at a median age of 2 years (range 1-28 yrs), and adults at a median of 4 years after banding (range 0-27 yrs). The peak of band recoveries occurred close to the peak of banding in the late 1960s. Recoveries were generally made between latitudes 30-55

A previously unknown population of Coenocorypha snipe was discovered on Jacquemart Island, a rat-free 19 ha islet adjacent to Campbell Island in the New Zealand subantarctic, on 9 November 1997. This was the first evidence of Coenocorypha snipe occurring in the Campbell Island group, which is believed to have been infested by Norway rats (Rattus norvegicus) before the first naturalists visited in 1840. Rats were eradicated from 11,268 ha Campbell Island by the New Zealand Department of Conservation in July 2001. Two snipe were seen, and one caught, on Campbell Island adjacent to Jacquemart Island on 10 March 2005. The bird caught was a fully-feathered chick, indicating successful breeding on Campbell Island. The Campbell Island snipe remains undescribed and critically endangered.