The Antipodean wandering albatross (Diomedea antipodensis) is endemic to Antipodes Island in the New Zealand subantarctic. A programme of regular census and population study was initiated on Antipodes Island in 1994 to determine the status of the species. This paper reports on field work carried out every summer from 1994 to 2005. Aspects of breeding biology are described and compared with those of other species of wandering albatross, particularly the closely related Gibson’s wandering albatross (D. gibsoni) on Adams Island. Average annual survival over 10 years was 0.957. Productivity was measured over 11 years and averaged 0.74 chicks per nesting pair. Survivorship was similar to that in the increasing Diomedea exulans population on Crozet Island, and productivity higher than recorded in all other wandering albatross populations. Between 1994 and 1997, the average annual number of pairs nesting on Antipodes Island was 5136. There is evidence of population decline during the 1970s but numbers are now increasing.
Observations of birds on Antipodes Islands during 24 April – 6 June 2001 represent a season of the year for which data are lacking. Activity ashore of non-breeders of summer-breeding gadfly petrels Pterodroma spp. and black- bellied storm petrels (Fregetta tropica) continued until late May or even June. Data were obtained on the non-breeding behaviour, breeding cycle and burrow occupancy rates of grey petrels (Procellaria cinerea); only 50% of their burrows were occupied by breeding pairs. White-capped albatross (Thalassarche steadi) fledglings on Bollons Island were counted. There had been an autumnal immigration of some Passerines. Birds seen at sea on the voyages from Akaroa, Banks Peninsula and returning to Port Chalmers, Dunedin included the rarely-sighted Chatham taiko (Pterodroma magentae).
We examine whether mist-netting and handling of birds (including taking blood samples) during the pre-nesting period caused egg-laying to be delayed in a threatened species, South Island saddleback (tïeke) Philesturnus carunculatus carunculatus. We used data on egg-laying dates of first clutches for 12 pairs in 2002-03 and 22 pairs in 2003- 04, of which 3 (2002-03) and 7 (2003-04) pairs had been caught and handled. There was a significant delay in the peak laying period of first clutches in 2003-04, which was associated with more birds being caught and handled. However, pairs that were handled showed typical laying dates of first clutches for both experienced and inexperienced pairs, and there was no significant correlation between the date when a pair was caught and the date of laying its first clutch. There were also no significant differences between handled and non-handled pairs in the number of chicks raised or fledged. Like saddlebacks, Stewart Island robins Petroica australis rakiura monitored at the same site showed a two-week delay in the average laying dates of first clutches in 2003-04. The five inexperienced robin pairs in 2002-03 laid their first clutches earlier in 2003-04, but all three experienced pairs laid later. Weather data indicated it was substantially colder before the nesting period in 2003 compared to 2002, suggesting that colder weather conditions plus a greater number of inexperienced pairs caused a delay in peak egg laying in both species in 2003-04 relative to 2002-03. We conclude that mist-netting, banding and bleeding – standard technique used in present-day research of threatened avian species – did not have any measured short-term effects on nesting behaviour or breeding success of South Island saddlebacks.
Five introduced bird species were observed in the wild in Samoa in November 2004. The red junglefowl Gallus gallus maintains wild populations in the mountainous areas; the rock dove Columba livia is presently confined to urban areas; and the red-vented bulbul Pycnonotus cafer and jungle myna Acridotheres fuscus have increased their ranges markedly over the past six years. The last two species, found in most inhabited areas, may be close to their maximum possible distribution in Samoa. The common myna Acridotheres tristis has also increased in range significantly and efforts should be made to control this species.
Counts, mark-recapture estimates of abundance, and simulations were used to assess the population trends of Antipodean wandering albatross (Diomedea antipodensis) and Gibson’s wandering albatross (D. gibsoni). Estimates of population size based on mark-recapture analysis had much greater power to detect trends than did annual counts of nests. In fact, nest counts were so variable that significant trends would only be detected when populations had already changed by more than 25%. Population simulation models were constructed using survival and productivity data from the two species, and recruitment data from closely related species. The simulation models were sensitive to variation in recruitment data and suggested that the recruitment of Gibson’s wandering albatrosses is significantly lower than that of Antipodean wandering albatrosses. The sensitivity of the models to variation in the surrogate data compromises the usefulness of such models as predictive tools. After large, probably fisheries-induced declines during the 1970s and 1980s, Antipodean wandering albatross populations are now increasing at about 3.1% per annum, while Gibson’s wandering albatross populations are static.
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.