Population study of Southern Buller's albatrosses on The Snares 2017

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Summary

This report presents a summary of the results of the collection of demographic data at three study colonies of Southern Buller's Albatross breeding at The Snares from 3 to 6 April 2017.

Demographic studies at the three study colonies have been undertaken annually since 1992, this report incorporates some of these data in the current analysis. Estimates of the numbers of breeding pairs, made by recording the contents of each nest mound, showed increases in all three colonies over the numbers recorded during 2016.

With the assumption that the combined total number of breeding pairs in the three study colonies was representative of North East Island as a whole then the breeding population probably peaked in 2005-2006 and has since undergone marked annual variations.

A total of 247 birds that had been banded previously in the study colonies as breeding adults of unknown age were recaptured. A further 56 breeding birds were banded in the study colonies - these are presumed to be first-time breeders.

During the period 1992-2004 all chicks that survived to near-fledging in the study colonies were banded and their survival to return to the study colonies in subsequent years has been monitored. This year 124 of these birds were recaptured, with 18 birds from cohorts banded from 1998 to 2004 being recaptured for the first time, and so showing the long-term monitoring required to obtain reliable estimates of survival of such known-age birds.

A further 25 known-age birds, from cohorts banded 1996-2004, were found breeding for the first time, and so were recorded as being recruited to the breeding population. One bird banded as a chick in 1972 was recaptured and at 45 years old is the oldest recorded known-age Southern Buller's Albatross.

Estimates of the annual survival of adults shows that this has declined from 0.95 in the period 1992-2004 to 0.91 in the period 2005-2016. However, since 2012 the recruitment rate has increased from 10-11% to 16-21%. It is likely that this higher recruitment is sustaining the breeding population and without it the breeding population would decline.

Publication information

Sagar, P., Thompson, D. & Scofield, P. 2017. Population Study of Southern Buller's Albatross on The Snares. Report prepared for the Deepwater Group Limited. 13 p.