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POP2022-08 White-capped albatross population study, Disappointment Island 2024 (PDF, 811K)
Summary
White-capped albatross
White-capped albatrosses are the most frequently incidentally bycaught albatross species in New Zealand commercial fisheries. The species ranks highly in New Zealand Government risk assessment, with uncertainty around the estimate of adult survival. A white-capped albatross mark-recapture study was established on Disappointment Island in January 2015 to improve estimates of adult survival, and other key population demographic parameters. A 3.5-day research trip to Disappointment Island was conducted 18–21 January; the tenth visit to the island for white-capped albatross survival rate research. Annual survival rates for white-capped albatrosses vary substantially year-on-year, ranging between 0.83 ± 0.06 (± SE) in 2015 to 0.96 ± 0.03 in 2020. Mean annual survival over that period was 0.89 ± 0.04 (excluding the estimate for 2018 which had particularly high variance). Robust estimates of survival and productivity of white-capped albatross require continued visits to Disappointment Island. Banding should be a high priority to ensure the core mark-recapture study is not compromised, since precision of survival estimates is reliant on it. Tracking devices, and cameras to assess productivity, were also recovered and deployed.
Gibson's albatross
Gibson’s wandering albatross (Diomedea antipodensis gibsoni) have been in decline since 2005. Research into the causes of and solutions to the falling numbers of Gibson’s wandering albatross includes an annual visit to the main breeding grounds on Adams Island and this report describes the results of the 2024 breeding season. Breeding success in 2023 was close to the mean (60%) though chick development was slower and fledging later than usual. The number of nesting pairs in three representative census blocks in 2024 was the lowest it has been since the 2006 population crash, likely due in part to the relatively high numbers nesting the previous summer. However, there are signs the number of breeding pairs of Gibson’s wandering albatross is again in decline (2016 to present) after a slow but nearly significant growth rate for the decade 2006–2015.
The satellite transmitters taped to the back feathers of 22 juvenile Gibson’s wandering albatross in December 2022 remained attached for an average of 291 days with the longest lasting 540 days, much longer than transmitters on adults, presumably because juveniles delay their first moult. Juveniles were found to spend much more time than adults foraging in tropical waters north of 30 degrees (2.4% cf 0.6%), which means juveniles have greater exposure to interactions with tuna longline fishing fleets. Two of the juveniles wearing transmitters appear likely to have been caught by longliners in winter 2023, one near an Australian-flagged vessel off Queensland within the Australian EEZ and one near a Chinese Taipei-flagged vessel in the high seas north-east of New Zealand. Twenty adult Gibson’s wandering albatrosses were fitted with satellite transmitters in late December 2023, of which one breeding female was almost certainly caught in June 2024 in the mid Tasman Sea by a longliner flagged to Chinese Taipei.
Drone photographs were taken of 63% of the 4,040ha of Gibson’s wandering albatross breeding habitat on Adams Island, and the number of albatrosses on the ground seen in the photographs were counted. Concurrent ground calibration checks undertaken to determine the proportion of birds on the ground which had eggs provided a “correction factor” which varied from 30% to 88% depending on area and time of day, with an average 54% of birds on the ground having a nest with an egg. After correction for pretend breeders and failed nests, a total of 3,348 breeding birds were counted in the 2,565ha of albatross habitat which was successfully droned, an area which in the past supported 80% of the population. Assuming the distribution of albatrosses has not changed, an estimated 4,181 pairs of Gibson’s wandering albatrosses were breeding on Adams Island in 2024.
A strong El Nino weather system in summer 2024 brought a constant stream of northerly fronts which were too wet, windy and misty for drone flying, and left the western and eastern extremities of Adams Island still to be droned. This will be undertaken in January 2025, when some of the already-counted parts of the island will be re-counted, to account for differences due to interannual variation.
Publication information
Parker, G.C., Osborne, J., Sagar, R., Schultz, H., Rexer-Huber, K. 2024. White-capped albatross population study, Disappointment Island 2024. POP2022-08 Final report to the Conservation Services Programme, Department of Conservation. Parker Conservation, Dunedin. 14 p.
Elliott G, Walker K, Rexer-Huber K, Tinnemans J, Long J, Sagar R, Osborne J, Parker, G. 2024. Gibson’s wandering albatross: demography, satellite tracking and census. Final Report Prepared for New Zealand Department of Conservation.33 p.