Population studies of southern Buller’s albatrosses at Tini Heke / The Snares Islands and Hautere / Solander Islands
Published:
June 2024Download the publication
POP2023-02 Population studies of southern Buller’s albatrosses at Tini Heke/The Snares Islands and Hautere/Solander Islands (PDF, 957K)
Summary
This report presents a summary of the results of demographic studies at three study colonies of southern Buller’s albatrosses Thalassarche bulleri bulleri breeding at Tini Heke / The Snares from 6 to 16 April 2024. We also describe a brief visit to southern Buller’s albatross colonies on Solander Island on 9 March 2024.
Demographic studies at the three study colonies on The Snares’ North East Island have been undertaken annually 1992–2024, with the exception of 2018 and 2021. Estimates of the numbers of breeding pairs, made by recording the contents of each nest mound, decreased substantially in all three study colonies compared to 2023; with numbers in the Mollymawk Bay study colony being the lowest recorded during the current study. 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, with decreases in the past two years. If the decreases of 27.3% to 34.8% in the three study colonies are reflected in the population as a whole then this will be a major concern for the conservation status of the species.
A total of 315 birds that had been banded previously in the study colonies as breeding adults of unknown age were recaptured. A further 26 breeding birds were banded in the study colonies - these are presumed to be first-time breeders. Although the most recent estimate of annual survival of birds banded as breeders (0.93 ± 0.03) was similar to the previous year’s estimate of 0.94 ± 0.01, the last four estimates over the period 2018 to 2023 have varied between 0.84 and 0.94. 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 92 of these birds were recaptured, with birds from cohorts banded from 1994 and 2002 recorded as breeding for the first time. This demonstrates the long-term monitoring required to obtain reliable estimates of survival of such known-age birds. In addition, five birds that had been banded as near-fledging in the study colonies during Sep 2013 and Sep 2014 were also recaptured for the first time.
At the Snares Time Depth Recorders, (TDRs), Global Location Sensing (GLS) light-based geo-locators and IgotU Global Positioning System (GPS) data loggers were deployed on 13 breeding Buller’s albatrosses to investigate diving behaviour and at sea distribution patterns. These deployments were short-term, and 12 of 13 devices were recovered during the trip. Eight Druid satellite transmitting tags paired with eight GLS were also fitted to breeding Buller’s albatrosses and these were securely attached for long term deployments to inform year around at sea distributions.
In 2020 50 GLS tags were attached to the metal leg bands of breeding birds in the Mollymawk Bay study colony at The Snares; of these, 31 were retrieved in 2022, a further three during the 2023 field season, and one this year. A further 26 GLS tags were deployed at Mollymawk Bay study colony in the visit reported here.
Twelve replacement trail cameras were deployed to upgrade those previously installed in 2022 at breeding colonies on The Snares and set to record one photograph every hour during daylight for a further year.
Publication information
Sagar, P., Rexer-Huber, K., Thompson, D., Parker, G. 2024. Population studies of southern Buller’s albatrosses at Tini Heke / The Snares Islands and Hautere / Solander Islands. DRAFT Final report to the Conservation Services Programme, Department of Conservation. Parker Conservation, Dunedin. 13 p.
Contact
Conservation Services Programme
Department of Conservation
PO Box 10-420
Wellington 6143
Email: csp@doc.govt.nz