An estimate of the population sizes of Black-browed (Thalassarche melanophrys) and Grey-headed (T. chrysostoma) Albatrosses breeding in the Diego Ramírez Archipelago, Chile
Graham Robertson A E , Carlos A. Moreno B , Kieran Lawton A , Javier Arata B , Jose Valencia C and Roger Kirkwood DA Australian Antarctic Division, Channel Highway, Kingston, Tas. 7050, Australia.
B Instituto de Ecología y Evolución, Casilla 567, Universidad Austral de Chile, Valdivia Chile.
C Instituto Antárctico Chileno, Plaza Muñoz Gamero 1055, Punta Arenas, Chile.
D Phillip Island Nature Park, PO Box 97, Cowes, Vic. 3922, Australia.
E Corresponding author. Email: graham.robertson@aad.gov.au
Emu 107(3) 239-244 https://doi.org/10.1071/MU07028
Submitted: 2 May 2007 Accepted: 7 August 2007 Published: 7 September 2007
Abstract
The Diego Ramírez Archipelago, Chile, is the southernmost albatross breeding ground in the world and holds globally important numbers of Black-browed (Thalassarche melanophrys) and Grey-headed (T. chrysostoma) Albatrosses. A census in the Diego Ramírez Archipelago has been attempted only once, in 1980–81, with methods that were unlikely to determine population sizes accurately. The number of breeding pairs of both species was estimated in the incubation period of 2002 using a combination of aerial photography, ground-based photography, yacht-based photography and ground counts. All islands in the archipelago were surveyed. There were an estimated 55 000 pairs of Black-browed and 17 000 pairs of Grey-headed Albatrosses breeding at the archipelago. Based on the results of this census, and those for the other four known breeding locations, the populations of both species of albatrosses in Chile are considerably larger than previously reported, comprising ~20% of the Black-browed Albatrosses and 23% of Grey-headed Albatrosses in the world, with the largest populations of both species occurring in the Diego Ramírez Archipelago.
Acknowledgements
We are grateful to the Armada de Chile for permission to camp and work at Isla Bartolomé, to Roger Wallis, skipper of the S/V Spirit of Sydney, for landing us on the island and to Sergio Cortez for piloting the Twin Otter aircraft. Comments by Barbara Wienecke, Mike Double, Sally Poncet and two anonymous referees improved a draft.
Arata, J. , Robertson, G. , Valencia, J. , and Lawton, K. (2003). The Evangelistas Islets, Chile: a new breeding site for black-browed albatrosses. Polar Biology 26, 687–690.
| Crossref | GoogleScholarGoogle Scholar |
Delord, K. , Gasco, N. , Weimerskirch, H. , and Barbraud, C. (2005). Seabird mortality in the Patagonian toothfish longline fishery around Crozet and Kerguelen Islands, 2001–2003. CCAMLR Science 12, 53–80.
González-Zevallos, D. , and Yorio, P. (2006). Seabird use of discards and incidental captures at the Argentina hake trawl fishery in the Golfo San Jorge, Argentina. Marine Ecology Progress Series 316, 175–183.
| Crossref | GoogleScholarGoogle Scholar |
Lawton, K. , Robertson, G. , Valencia, J. , Wienecke, B. , and Kirkwood, R. (2003). The status of Black-browed Albatrosses Thalassarche melanophrys at Diego de Almagro Island, Chile. Ibis 145, 502–505.
| Crossref | GoogleScholarGoogle Scholar |
Schlatter, R. P. , and Riveros, G. M. (1997). Historia natural del Archipiélago Diego Ramírez, Chile. Serie Científica Instituto Antárctico Chileno 47, 87–112.