Salvin's albatross population size and survival at The Snares Western Chain

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POP2014-02-Objective 2. Salvin's albatross population size and survival at the Snares Western Chain (PDF, 1,018K)

Summary

This report presents a summary of the results of whole-island counts of Salvin’s albatrosses Thalassarche salvini breeding at the Snares Western Chain on 17 September 2014 and compares these results with those obtained using similar methods during 2008 and 2009. In addition, the results of ground-truthing of an aerial survey and a survival analysis based on the recapture of banded birds are presented.

The whole-island surveys used the same methods as those in 2008 and 2009. The survey of Toru and Rima Islets and a rock stack just east of Toru resulted in an estimate of  1213 breeding pairs, which was very similar to the 1195 and 1116 breeding pairs estimated in 2008 and 2009, respectively, indicating that the population has remained stable over the intervening period.

Counts along transects immediately after the aerial survey showed that of 171 birds ashore, 100 (58.5%) were incubating, 14 (8.2 %) were on empty nests, and 57 (33.3 %) were loafing. The relatively high proportion of loafing birds may be a result of breeding failure as a consequence of habitat and disturbance by other birds prior to the survey.

On Toru Islet, a total of 67 birds that had been banded previously as chicks on the nest (in 1986) or breeding adults of unknown age (in 1995, and annually 2008-2010) were recaptured. Analysis of these data in a mark-recapture model resulted in an estimated survival probability of 0.951. This remains among the highest estimated survival of any population of annual breeding albatrosses.

Publication information

Sagar, P., Charteris, M., Scofield, P. 2014. Salvin's albatross population size and survival at The Snares Western Chain. Report prepared by the National Institute of Water and Atmospheric Research for the New Zealand Department of Conservation, Wellington. 17p.