Archived 2012-2013 topics: Grey-headed Albatross (Thalassarche chrysostoma): uplist to Endangered?

BirdLife Species Factsheet for Grey-headed Albatross Grey-headed Albatross Thalassarche chrysostoma is currently listed as Vulnerable under criterion A4bd on the basis of an estimated population decline of 30-49% over three generations (90 years).  This estimate is based on documented declines to date suggesting that the population has decreased by 15% since the mid-1980s, which, if continued, would equate 49% over three generations. However, given the uncertainty around these estimates, particularly the likely future trends, and the long trend period, a decline of 30-49% over 90 years was provisionally estimated. Approximately half the global population of Grey-headed Albatross breeds on South Georgia (Georgias del Sur), with a further c.18% breeding in Chile, c.15% on the French islands of Iles Kerguelen and Iles Crozet in the southern Indian Ocean, 8% on Campbell Islands, and 10% in the Prince Edward Islands (ACAP 2010). At South Georgia, the population is estimated to have declined by 25% between 1977 and 2004 (R. Phillips verbally 2012), which equates to a projected decline of 85% 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 (Moore 2004; Nel et al. 2002), which would equate to a 95% decline over three generations. 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), which would equate to a doubling of the population over three generations. Combing these data (see attached spreadsheet), 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 62.6% over three generations. This suggests that, despite the variability in data quality and considerable uncertainty over trends for this biennial breeder, the species could qualify as Endangered under criterion A4bd. Discussion is welcomed on whether, given reanalysis of the best available data, it is appropriate to estimate an ongoing population decline of 50-79% over three generations (90 years), which would result in the species being uplisted to Endangered. If so, it would be important to pinpoint when the rate of population decline is thought likely to have first exceeded 50% over three generations (was this prior to, or since 1988?). In addition, any count data from colonies lacking more recent information is sought to enable more accurate assessment of trends. Thalassarche chrysostoma trend analysis References: ACAP. 2010. ACAP Species Assessment: Grey-headed Albatross Thalassarche chrysostoma. Downloaded from http://www.acap.aq on 22 March 2013. Moore, P. J. 2004. Abundance and population trends of mollymawks on Campbell Island Nel, D. C.; Ryan, P. G.; Crawford, R. J. M.; Cooper, J.; Huyser, O. 2002. Population trends of albatrosses and petrels at sub-Antarctic Marion Island. Polar Biology 25: 81-89