EN
Grey-headed Albatross Thalassarche chrysostoma



Justification

Justification of Red List Category

This species is listed as Endangered as data from South Georgia (Georgias del Sur), which holds around half the global population, indicate a very rapid rate of decline of the world population over three generations (90 years), even if colonies lacking trend information are assumed to be stable. The major driver of declines is likely to be incidental mortality in longline fisheries.

Population justification
There are an estimated c.98,601 pairs breeding per year of this biennially breeding species, based on annual breeding population estimates of 47,674 pairs on South Georgia in 2004 (Poncet et al. 2006), 18,063 pairs in Chile in 2015 (Robertson et al. 2007, 2008, 2016), 7,900 pairs on Kerguelen in 1987 (Weimerskirch et al. 1988), 8,611 pairs on Campbell Island (Sagar 2014), 8,541 pairs on Marion Island in 2016 (ACAP unpubl. data), 5,940 on Crozet in 1982 (Jouventin et al. 1984), 1,506 pairs on Prince Edward Island in 2009 (Ryan et al. 2009) and 100 pairs on Macquarie Island in 2016 (ACAP unpubl. data). This is thought to be equivalent to at least 250,000 mature individuals (Croxall and Gales 1998, Brooke 2004).

Trend justification
At South Georgia, the population is estimated to have declined by 25% between 1977 and 2004 (Poncet et al. 2006, R. Phillips pers. comm. 2012) , and by 43% between 2004 and 2015 (Poncet et al. 2017), which equates to a projected decline of 85% or even higher if declines continued at this rate over three generations. On Campbell Island, data from 2004 suggest that the population declined by over 75% between 1940 – 2004 (Nel et al. 2002, Moore 2004), which would equate to a 95% decline over three generations. However, recent unpublished information suggests that this population underwent a major decline until 1997 but has since stabilised (W. Misiak in litt. 2013). Population trends are unknown for Chile, Iles Kerguelen and Iles Crozet (representing around one third of the global population). Also, in contrast to South Georgia and Campbell Island, the population on Marion Island has reported a 1.2% annual population increase from 1988-2011 (ACAP 2012). Combining these data, even if the Chilean, Iles Kerguelen and Iles Crozet colonies are assumed to be stable, the data from South Georgia and Campbell Island result in a projected global population decline of 65.4% over three generations. Given the uncertainty around these estimates, particularly the likely future trends, and the long trend period, a decline of 50-79% over 90 years is provisionally estimated.

Distribution and population

Thalassarche chrysostoma has a circumpolar distribution over cold subantarctic and Antarctic waters (ACAP 2009, Clay et al. 2016). It breeds on South Georgia (Georgias del Sur), Islas Diego Ramirez and Ildefonso (Chile), Prince Edward and Marion Islands (South Africa), Crozet Islands, Kerguelen Islands (French Southern Territories), Campbell Island (New Zealand) and Macquarie Island (Australia). The annual breeding population is c.95,000 pairs, equivalent to a total population of c.250,000 mature individuals in this biennial breeder (Croxall and Gales 1998, Brooke 2004). Approximately half of the global population breeds on South Georgia (ACAP 2009). Its range at sea while breeding lies largely within or south of the Antarctic Polar Frontal Zone (Prince et al. 1998, Phillips et al. 2004). During the non-breeding season, birds range widely in subantarctic to Antarctic waters, and a proportion make one or more global circumnavigations, the fastest in just 46 days (Croxall et al. 2005, Clay et al. 2016). Birds banded in New Zealand have been recovered in Australian waters (G. Taylor in litt. 2008). At South Georgia, the population is estimated to have declined by 25% between 1977 and 2004 (Poncet et al. 2006, R. Phillips pers. comm. 2012) , and by 43% between 2004 and 2015 (Poncet et al. 2017), whereas at Campbell Island the population underwent major declines prior to 1997 but has apparently since stabilised (Sagar 2014). Population trends are unknown for Islas Ildefonso, Iles Kerguelen and Iles Crozet (representing around 14% of the global population), and increasing on Marion Island and Islas Diego Ramirez (ACAP 2016). Even if it is assumed that colonies without trend information have remained stable, the global population is assumed to be in rapid decline, given the trend at South Georgia.


Ecology

Behaviour This species is normally a biennial breeder, although 5.4% and 1% of successful breeders on Marion Island and Bird Island (South Georgia) respectively, breed in the following season. Birds return to colonies between late September and early October, laying occurs in October and chicks hatch by December. Chicks fledge from April to May. Immatures return to breeding colonies at the earliest at 3 years of age, but generally at 6 or 7 years old. First breeding can be as early as 7 years, but the average on Campbell Island is 13.5 years old, and the modal age on South Georgia is 12 years old. Grey-headed Albatrosses feed by surface-seizing but can also dive to six metres (Huin and Prince 1997). Substantial segregation in foraging areas is apparent for male and female Grey-headed Albatrosses during incubation at South Georgia, with males travelling on average further than females (Phillips et al. 2004). At Iles Kerguelen, Campbell Island and South Georgia (Islas Georgias del Sur), the species is principally an oceanic forager, concentrating its foraging in the Antarctic Polar Frontal Zone, but in years of low food availability, chick-rearing birds from South Georgia (Islas Georgias del Sur) increase the proportion of time spent in Antarctic shelf-slope waters. Prey biogeography also indicates some neritic foraging around Iles Kerguelen and Campbell Island during chick rearing (ACAP 2009). At Marion Island, incubating birds foraged in the Sub-tropical Frontal Zone and the Subantarctic Zone in association with mesoscale eddies, whereas during chick-rearing, foraging was concentrated in the Subantarctic and Polar Frontal Zones to the south-west of the island, also in association with eddies (Nel et al. 2000, 2001). Habitat Breeding This species breeds on steep slopes or cliffs, that are generally covered with tussock-grass. Diet The diet varies with locality and year, mainly consisting of cephalopods and fish, but crustaceans, carrion and lampreys are locally important (Prince 1980, Cherel et al. 2002, Xavier et al. 2003, Arata et al. 2004). It actively scavenges longline baits.

Threats

Incidental capture by commercial longline fisheries represents a major threat to this species. In Australian waters, up to c. 400 individuals (over 80% juvenile) were killed annually in 1989-1995 by Japanese longliners (Gales et al. 1998). Despite mainly foraging over oceanic waters, the species also interacts with longline fisheries targeting Patagonian Toothfish Dissostichus eleginoides in shelf areas (ACAP 2009). In the Indian Ocean, illegal or unregulated fishing for Patagonian Toothfish killed an estimated 10,000-20,000 albatrosses (mainly this species) in 1997 and 1998 (CCAMLR 1997, CCAMLR 1998). Due to its circumpolar distribution, T. chrysostoma is potentially vulnerable to Southern Ocean pelagic fisheries worldwide (with the exception of the New Zealand Exclusive Economic Zone; G. Taylor in litt. 2008). The extensive use of the Subtropical Convergence and Sub-Antarctic Zones by incubating birds from Marion Island, especially females, bring them into contact with intense Southern Bluefin Tuna Thunnus maccoyii longline fishing activity in international waters (40-45°) (ACAP 2009). In addition, bycatch of Grey-headed Albatross has also been recorded in the poorly regulated small-scale longline operations off the coast of Peru, suggesting that mortality in these operations is also significant (Mangel 2012).

Long-term declines on Campbell began well before local longline fishery development, and appear to be caused by environmental factors, possibly rising sea-surface temperatures resulting in food shortages. Pardo et al. (2017) demonstrated that adult mortality from bycatch was exacerbated by El Niño Southern Oscillation (ENSO) and associated reductions in food availability, indicating that periodic temperature extremes are at least contributing to a significant population decline.

Another threat is posed by introduced House Mice Mus musculus. On Marion Island, up to 5% of Grey-headed Albatross chicks are killed by mice each year and the rate is likely to increase unless mice are eradicated (Dilley et al. 2016).

Conservation actions

Conservation Actions Underway
CMS Appendix II and ACAP Annex 1. Population monitoring and foraging studies are being undertaken at South Georgia, Diego Ramirez, Marion, Macquarie and Campbell Islands. Macquarie and Campbell are World Heritage Sites and the Prince Edward Islands are a Special Nature Reserve.

Conservation Actions Proposed
Continue existing monitoring and commence at poorly-known sites (Environment Australia 1999). Determine migration patterns in off seasons from other populations and overlap with fisheries, particularly those operating in the southern Indian Ocean. Promote adoption of best-practice mitigation measures in all fisheries within the species's range, particularly via intergovernmental mechanisms such as ACAP, CCAMLR and FAO.

Identification

81 cm. Small albatross with dark ashy-grey head, throat and upper neck. Blackish upper wings, mantle and tail. White rump. White crescent behind eye. Black bill with bright yellow upper and lower ridges, shading to pink-orange at tip. White underparts. White underwing with much black on leading edge, less on trailing edge. Immature has mostly black bill and head, nape darker than adult, indistinct white eye-crescent, virtually no white on underwing. Similar spp. Underwing pattern distinguishes it from Buller's Albatross T. bulleri (which has more yellow on bill), yellow-nosed species, and Shy Albatross T. cauta, Chatham Albatross T. eremita and Salvin's Albatross T. salvini. Immatures difficult.

Acknowledgements

Text account compilers
Stuart, A., Sullivan, B., Symes, A., Butchart, S., Fjagesund, T., Anderson, O., Hermes, C., Martin, R., Calvert, R., Moreno, R., Small, C.

Contributors
Robertson, C., Gales, R., Wolfaardt, A., Misiak, W., Phillips, R., Arata, J., Ryan, P.G., Croxall, J., Xavier, J., Cooper, J.


Recommended citation
BirdLife International (2019) Species factsheet: Thalassarche chrysostoma. Downloaded from http://www.birdlife.org on 10/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 10/12/2019.