EN
Antipodean Albatross Diomedea antipodensis



Justification

Justification of Red List Category
This species is considered to be undergoing a very rapid decline in population size. For this reason it is assessed as Endangered.

Population justification
G. Elliot and K. Walker (in litt. 2017) roughly equated the global population size to be 50,000 mature individuals in 2016, based on an approximate annual breeding population of 9,050 breeding pairs, with the vast majority of individuals breeding on Adams and Antipodes Islands. However, since 2004 there has been a dramatic decrease in the population size and number of nests found on these two islands (see Elliott and Walker 2014, Elliott et al. 2016), and so the population size is likely smaller than this now.

Trend justification
Although both main populations had been stable or increasing in the 10 years up until 2004 (Elliott and Walker 2014, Elliott et al. 2016), both have subsequently declined dramatically. In 2016, the Auckland Island population had declined by 40% and the Antipodes Island population by about 60% from their peaks in 2004 (K. Walker and G. Elliott in litt. 2017). The most recent mark-recapture studies indicate a decline of 2.1% per annum in both males and females on the Auckland Islands over the last 10 years (Elliott et al. 2016) and 8.6% and 4.9% per annum for females and males respectively on Antipodes Island over the last 7 years (G. Elliott and K. Walker, unpubl. data). Recent surveys of Antipodes and Adams Islands (Elliott and Walker 2014, Elliott et al. 2016) combined with unpublished data suggest that declines may be 97.6% over 3 generations (82 years) (K. Walker and G. Elliott in litt. 2016). Modelling exercises have also predicted very large declines. Combining the rate of decline for Antipodes (Edwards et al. 2016 per K. Walker and G. Elliott in litt. 2016) and Adams (Francis et al. 2015 per K. Walker and G. Elliott in litt. 2016) give an annual decline of 5.7% per year, equating to a 99% decline over 3 generations. However, since the data appear to show that the population was stable or increasing prior to 2004, recent declines may be related to a population cycle rather than a true decline. There are plausible threats to explain population declines, so it is suspected that declines may continue at least some way into the future. Taking approximate numbers of breeding birds from the figures in Elliott and Walker (2014) and Elliott et al. (2016), and restricting the number of mature, breeding individuals to the number of females x2 (to take into account the species's sex imbalance), the estimated reduction roughly equates to 52% between 2004 and 2014. If all adults were included, the decline would equate to roughly 44%, but given that threats may continue into the future it may be assumed that the population will decline sufficiently in the subsequent 72 years that the rate of decline may be >50% over a 3 generation period that encompasses the past and the future.

Distribution and population

This species is endemic to New Zealand, breeding on Antipodes Island, the Auckland Islands group (Adams, Disappointment and Auckland), Campbell Island and Pitt Island in the Chatham Islands (one pair in 2004) (Miskelly et al. 2008, ACAP 2012). Data from satellite tracking indicate that birds from the Auckland Islands forage mostly west of New Zealand over the Tasman Sea and south of Australia, while those from the Antipodes forage east of New Zealand in the South Pacific, as far as the coast of Chile, and have a larger overall range (Medway 1993, Taylor 2000, Walker and Elliott 2006). The species does not breed every year, and may defer up to two years between breeding attempts (ACAP 2012), and so the number of individuals breeding annually does not equate to the number of individuals in the population. G. Elliot and K. Walker (in litt. 2017) roughly equated the global population size to be 50,000 mature individuals in 2016, based on an approximate annual breeding population of 9,050 breeding pairs, with the vast majority of individuals breeding on Adams and Antipodes Islands. However, since 2004 there has been a dramatic decrease in the population size and number of nests found on these two islands (see Elliott and Walker 2014, Elliott et al. 2016), and so the population size is likely smaller than this now.

Ecology

Behaviour Eggs are laid between late December and late January on the Auckland Islands, and between early January and early February on the Antipodes Islands. Hatching takes place between March and April, and chicks fledge after nine months departing in mid-December to early March (ACAP 2009). Breeding is biennial if chicks are successfully reared (Gales 1998). Fledglings do only return when three years old. The youngest age of first breeding in the 1990s was seven years for Antipodes Island birds and eight years old for Auckland Island birds (ACAP 2009), but has risen in recent years, at least in Antipodes Island birds, to 12 years (Edwards et al 2016). Between 1991 and 2004, average productivity was 74% on Antipodes Island, but lower (63%) on the Auckland Islands (Elliot and Walker 2005). Foraging was most concentrated over pelagic waters and deep shelf slope (up to 6,000 m), with peaks of activity at 1000 m corresponding to seamounts and shelf breaks where productivity is high (Walker and Elliott 2006). Foraging trips are longer during incubation (7-13 days) than during chick-rearing (average 4 days) (ACAP 2009). Breeders and non-breeders have similar core foraging areas, though non-breeding individuals from the Antipodes Islands migrate east to the waters off Chile, and non-breeding juvenile males and females from the Auckland Islands forage westward to the south-eastern Indian Ocean (Walker and Elliott 2006, G. Elliott and K. Walker, unpubl. data).
Habitat Breeding It nests from the coastline inland, on ridges, slopes and plateaus, in open, low tussock grassland, sometimes with occasional shrubs.
Diet It feeds mostly on cephalopods and fish (ACAP 2009, Xavier et al. 2015).

Threats

Bycatch in longline fisheries is a key threat to this species (ACAP 2012). Since 1987, the species has been known to make up a substantial proportion of bycatch in the longline tuna fishery in New Zealand waters. In 2006, 58 birds were captured during a single fishing trip in this region, with significant mortality also occurring in the Chilean pelagic longline swordfish fishery (ACAP 2009). The species’ foraging area overlaps with the Australian Eastern Tuna and Billfish fisheries, the Korean and Taiwanese fleets targeting Albacore Tuna Thunnus alalunga in the Pacific and the Spanish long-line fleet targeting swordfish Xiphias gladius. The level of threat from fisheries is currently increasing, and individuals, particularly females, are observed to extending the travel distance on foraging trips. Shifts in the at-sea distribution of non-breeding females may also be related to changing oceanic conditions driven by climate change, impacting on food resources and potentially increasing the risk from bycatch. The interaction between climate change and bycatch is a likely explanation for the observed faster decline of the female population relative to the male population (Walker et al. 1995, Walker and Elliot 1999, Elliott et al. 2016). In 2005 and 2006, female annual survival was as low as 80%, eight percent below male survival, and there is now a strong sex imbalance within the population (Elliott and Walker 2014, Elliott et al. 2016), further reducing the effective population size. The impact of at-sea threats is also exemplified by the recent decline in the two main populations on the Antipodes and Adams Island. The sub-population was previously increasing, but has now declined by 6% and 12% respectively, in the absence of any apparent land-based threats (ACAP 2017). Pigs Sus domesticus may be responsible for the near-extirpation of the species on Auckland Island, and probably still take eggs and chicks, while feral cats Felis catus potentially also contributing to chick mortality (Taylor 2000). Introduced House Mice Mus musculus on the Antipodes Islands do not appear to pose a threat to the species at present (ACAP 2009).

Conservation actions

Conservation Actions Underway
ACAP Annex 1. Conservation efforts began in 1969, when the breeding population was first estimated on Antipodes. Thousands of chicks have been banded, both on Antipodes and Adams Islands. Satellite tracking has identified foraging and non-breeding distribution (Walker and Elliott 2006). By 1992, cattle and sheep had been eradicated from Campbell Island (Taylor 2000). All islands are nature reserves and, in 1998, were declared part of a World Heritage Site. In 2016 an attempt was made to eradicate mice from Antipodes Island, with the outcome still unknown.

Conservation Actions Proposed
Census total breeding population for 3-4 consecutive years at 10-year intervals. Monitor productivity, survival and recruitment. Check all birds for bands during censuses for survival and recruitment measures. Monitor new fisheries and distant-water pelagic fleets in the Pacific for bycatch. Continue to develop mitigation devices/techniques to minimise fisheries bycatch, extend the obligatory use of mitigation measures to waters below 25 degrees south and monitor compliance with regulations regarding use of bycatch mitigation measures. Eradicate pigs and cats from Auckland Island (Taylor 2000). Investigate the impact that oceanographic changes in the south Pacific Ocean may be having.

Identification

110 cm. Huge albatross breeding in mixed white and brownish plumage. Juvenile very similar to juvenile Wandering Albatross D. exulans. Birds breeding on Auckland Island (subspecies D. a. gibsoni) are generally paler than those on Antipodes, Chatham and Campbell Islands (subspecies D. a. antipodensis). Breeding females have chocolate-brown upperparts with white vermiculations on back, white face mask and throat, white lower breast and belly with brown undertail-coverts, and white underwing with dark tip. Breeding females of D. a. antipodensis have broad brown breast-band. Breeding males are whiter than females but never as white as whitest Wandering Albatross. Pink bill. Males of D. a. antipodensis may be distinguished from D. a. gibsoni by darker cap and tail, and less white on the humeral flexure. Similar spp. Wandering Albatross is significantly larger, but possibly not separable with certainty in field. Bill lacks dark marks of Amsterdam Albatross D. amsterdamensis.

Acknowledgements

Text account compilers
Wheatley, H., Fjagesund, T., Butchart, S., Hermes, C., Martin, R., Small, C., Stuart, A., Sullivan, B., Calvert, R.

Contributors
Walker, K., Elliott, G., Taylor, G.A., Robertson, C., Stahl, J.-C.


Recommended citation
BirdLife International (2020) Species factsheet: Diomedea antipodensis. Downloaded from http://www.birdlife.org on 18/01/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/01/2020.