Post-fledging survival and dispersal of shy albatross from three breeding colonies in Tasmania
Alderman, RL and Gales, R and Hobday, AJ and Candy, SG, Post-fledging survival and dispersal of shy albatross from three breeding colonies in Tasmania, Marine Ecology - Progress Series, 405, (Supplement) pp. 271-285. ISSN 0171-8630 (2010) [Refereed Article]
Limited knowledge of the movements of post-fledging albatross represents a significant gap in understanding albatross biology and conservation. Without clearer understanding of at-sea distribution and mortality during this life-history stage, the threats to albatrosses cannot be managed appropriately. We investigated this early at-sea behaviour of shy albatrosses Thalassarche cauta, which breed only in Tasmania. We deployed 48 satellite transmitters on fledgling birds from each of the 3 Tasmanian populations over 4 separate seasons. We observed population differences in the at-sea distribution, with the northern Albatross Island population foraging exclusively in southern Australian shelf waters to the west of the breeding colony. Birds from the 2 populations in southern Tasmania (Mewstone and Pedra Branca) also favoured these areas; however, they showed greater tendency to traverse the high seas and forage further west. These differences in spatial distribution mean populations have different exposure to fisheries and consequent risk of bycatch. Analysis of the satellite data and supporting evidence from band recoveries showed that juvenile mortality is highest in the period immediately after fledging. We speculate that this is related to foraging failure of naive birds. Differences between the 3 populations in post-fledging mortality were apparent. Albatross Island birds have greater chance of surviving the crucial initial learning period after fledging than either of the 2 southern populations, possibly due to proximity to food resources.