White‐capped albatross, adult survival and other demographic parameters, Auckland Islands 2017
Published:
June 2017Download the publication
Summary
The survival rates of breeding white-capped albatrosses was estimated from a five‐year study at Southwest Cape, Auckland Island. However, the Southwest Cape colony is small, and so the number of banded breeding birds and resighting visits were fewer than optimal, giving wide confidence intervals around estimates of adult survival rate.
A marked population of breeding adult white‐capped albatross was established at the largest colony on Disappointment Island, Auckland Islands with the long‐term aim to estimate key white‐capped albatross demographic parameters, including adult survival.
The work reported here comprises the set‐up phase of a study area established in a dense white‐capped albatross colony close to Castaways Bay. To support the interpretation of aerial photographs, an additional objective was to conduct ground‐truthing counts to estimate the proportion of breeding white‐capped albatrosses from those that are apparently incubating.
A total of 393 breeding white‐capped albatrosses have been banded in three annual visits to Disappointment Island 2015 – 2017. White‐capped albatross resighting rates of birds banded in previous years were 21% in 2016 and 24% in 2017. Ground‐truthing counts of incubating versus apparently incubating birds revealed that overall the proportion of incubating birds averaged 64% from 21 transects.
Two years of recaptures do not provide sufficient recapture histories for individuals to allow survival estimates. However our two short visits in 2016 and 2017 recorded encouraging resighting rates, given the short duration of visits that did not allow sufficient time for breeding pairs to changeover mates, and the primary focus of the work on banding and ground‐truthing (not resighting).
Ground‐truthing data show that counts of the breeding population of white‐capped albatrosses on Disappointment Island using aerial photography cannot provide an accurate or consistent estimate without calibration by ground‐truthing data of the number of birds apparently incubating.
As the proportion of incubators versus apparent incubators may vary around the island, we question whether sufficient ground truthing data can be collected to enable accurate estimates of the entire breeding population based on interpretation of aerial photography.
Publication information
Parker, G.C., Sagar, P., Thompson, D. & Rexer-Huber, K. 2016. White‐capped albatross – adult survival & other demographic parameters, Auckland Islands 2017. Report prepared by Parker Conservation for the Conservation Services Programme, Department of Conservation, Wellington. 14 p.
Contact
Conservation Services Programme
Department of Conservation
PO Box 10-420
Wellington 6143
Email: csp@doc.govt.nz