Trends in numbers and survival of Black-browed (Thalassarche melanophrys) and Grey-headed (T. chrysostoma) Albatrosses breeding on Macquarie Island
Aleks Terauds A B C , Rosemary Gales B and Rachael Alderman BA University of Tasmania, Churchill Avenue, Sandy Bay, Tas. 7005, Australia.
B Nature Conservation Branch, Department of Primary Industries, Water and Environment, PO Box 44, Hobart, Tas. 7000, Australia.
C Corresponding author. Email: Aleks.Terauds@dpiwe.tas.gov.au
Emu 105(2) 159-167 https://doi.org/10.1071/MU05026
Submitted: 10 June 2004 Accepted: 20 May 2005 Published: 30 June 2005
Abstract
Black-browed (Thalassarche melanophrys) and Grey-headed (T. chrysostoma) Albatrosses are globally threatened seabirds that breed on remote subantarctic islands. Population trends of Black-browed and Grey-headed Albatrosses breeding on Macquarie Island were described using historical data combined with data from a more intensive 10-year monitoring program. Survival estimates were also calculated for both species over similar time frames. Breeding numbers and survival rates of Black-browed and Grey-headed Albatrosses appear to have remained stable since the mid-1970s. There was no conclusive evidence of survival varying over time and it is unlikely that mortality owing to fisheries’ activities has had a significant impact on these populations. This is in contrast to most other subantarctic populations of these species and may be attributed to their foraging ranges not overlapping significantly with areas of high fishing effort. However, both species forage in areas of new and expanding legal and illegal fishery operations. Owing to their extremely small size, these populations remain chronically vulnerable to any elevated levels of mortality.
Acknowledgments
This project was jointly funded by the Australian Department of Environment and Heritage (formerly Environment Australia) and the Antarctic Scientific Advisory Committee (ASAC Project 751), and during fieldwork A.Terauds was funded by an Australian Postgraduate Award through the University of Tasmania (UTAS). Logistical support was provided by the Australian Antarctic Division and the Tasmanian Department of Primary, Industries, Water and Environment (DPIWE). We thank the Tasmanian Parks and Wildlife Service (TASPAWS) for providing access to historical data. These data were collected by many researchers and expeditioners on Macquarie Island since the 1950s and their contribution is gratefully acknowledged. G. Copson (DPIWE) and N. Brothers (TASPAWS) contributed significantly to this data collection during the 1970s and 1980s. We also thank all Macquarie Island Albatross Project workers since 1994 for their assistance in collecting the data. Thanks go also to the staff from the Australian Bird and Bat Banding Scheme, particularly to B. Dettmann for assistance with the mark–recapture analysis. A. Richardson (University of Tasmania) and B. Baker (Australian Antarctic Division) reviewed earlier versions of this manuscript and provided useful comments.
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