Antipodean Albatross and White-chinned Petrel research on Antipodes Island, 2024/25

An Antipodean Albatross breeding pair on Antipodes Island, photograph by Erica Sommer

Kalinka Rexer-Huber (Parker Conservation, Dunedin, New Zealand) and colleagues have produced a final report for the Conservation Services Programme of the New Zealand Department of Conservation that details research carried out on Endangered Antipodean Albatrosses Diomedea a. antipodensis and Vulnerable White-chinned Petrels Procellaria aequinoctialis on Antipodes Island during then 2024/25 austral summer.

The report’s summary follows:

“The Antipodean wandering albatross Diomedea antipodensis antipodensis has been in decline since a population crash in 2005–07.  Declining numbers appear to have been largely driven by high female mortality, but low chick production—with fewer birds breeding and reduced breeding success—has compounded the problem.  To tease out the causes of falling numbers of Antipodean wandering albatrosses and identify the effectiveness of potential solutions, research includes an annual visit to the breeding grounds on Antipodes Island.  Alongside this core annual study, we present results from a whole-island survey to estimate the size of the Antipodean albatross population nesting island-wide.  Alongside the albatross research, we are developing a mark-recapture study for white-chinned petrels.  This report describes the results of the annual field programme in the 2024/25 breeding season for both Antipodean albatrosses and white-chinned petrels.

Antipodean wandering albatross. The core annual study involves mark-recapture in an intensively monitored study area and census of the annual count areas.  This season’s field programme allowed updates to the trend in nesting population size, survival, productivity and recruitment.  There are some signs that rates of decline are slowing; for example, the population of breeding pairs was declining at -5.2% per annum (2008–2013), which has slowed to a -1.5% decline in the last decade 2014–2023. The number of Antipodean wandering albatrosses breeding has been roughly stable for the past four seasons, and female survival improved 2010–2019 to approach male survival rates.  Female survival has reached 91.2% (most  recent 4-year average), but this is still lower than for males (92.6%) and remains lower than females’ pre-crash average of 95.9%.  Breeding success in 2024 at 68% approached the average pre-crash nesting success of 74%, although the mean 2006–2024 rate remains comparatively low at 63%.  However, the actual number of chicks produced remains small, even in years with good breeding success, since numbers nesting remains low.  Recruitment is starting to draw from the (much smaller) cohorts produced since the crash, so population numbers will soon no longer be supplemented by higher recruitment rates seen over the past decade.

The last whole-island count of nesting Antipodean albatross took place 1994–96.  To update the whole-island estimate, we built on last year’s effort which combined ground counts and drone aerial photography producing orthomosaics of 77% of the Antipodean albatross breeding habitat.  This season drones were used to obtain photographs of the entire Antipodean albatross breeding habitat on Antipodes Island.  Orthomosaic images were constructed from the photos and the number of albatrosses counted and corrected for pretend-nesters (apparently-nesting birds with no egg) using data from nest-content checks conducted during drone overflight (has-egg rate).  A second correction used the proportion of eggs not yet laid or nests that had failed at the time the photographs were taken (lay-fail rate), using data from regular visits to the study area.  Just 1% of the 1546-ha Antipodean albatross breeding range was not overflown in 2025. Numbers in these unphotographed 22 ha were estimated by categorising nesting-habitat quality across the island, then extrapolating nest densities by habitat-quality class to the unphotographed areas.  The number nesting island-wide in 2025 estimated from drone counts (3,546±254 breeding pairs) and the 3,383±201 annual breeding pairs in 2024 provide two successive estimates that together account for biennial breeding and resulting year-on-year differences.  This is the first time since 1996 that the number of breeding pairs nesting on Antipodes Island have been comprehensively assessed across the island.  The proportion nesting in annual count blocks in 2024 (14%) and 2025 (14.7%) are similar to that recorded 1994–96 (14.9%), indicating that the annual count blocks remain representative of whole-island trends in nest numbers.

Trends in nest numbers and demographic parameters from the c ore annual study indicate that the population has been approximately stable for the last four years.  However, there is so far no evidence of any sustained improvement in Antipodean wandering albatross demography, as required for the population to recover, with tentative improvements recorded here merely slowing the decline.  Recommendations include ongoing mark-recapture monitoring of demographic and population-size trends, and research into causes of declines.  More-targeted ongoing engagement with fishers is also needed to achieve better bycatch mitigation in line with ACAP best practice.

White-chinned petrel.  A mark-recapture study to estimate vital rates, survival in particular, was established in the 2022–23 season.  Substantial effort to grow the mark-recapture study this year mean there are now 367 banded white-chinned petrels in 203 marked burrows in the two study areas.  For accurate, precise survival estimates this marked population needs recaptures at existing marked burrows for a minimum of two more years.  The two years of resighting data obtained to date are not yet enough for mark-recapture modelling to produce a useful survival estimate.  However, summary statistics highlighted the importance of quality monitoring data: startlingly low year-on-year return rates recorded last year (24% of birds that had been in the colony the previous season returned) were 76% this year, closer to the return rates expected for annual breeders.  Burrow reoccupancy was also better than the year prior, with 39% of burrows marked last year reoccupied this season, compared to just 27% the year before, although reoccupancy still appears low compared to the 44–68% recorded at Antipodes Island in a 2007–11 study.”

A White-chinned breeding pair on Antipodes Island, by Dave Boyle

Reference:

Rexer-Huber, K., Whitehead, E., Walker, K. & Elliott, G. 2025.  Antipodean wandering albatrosses and white-chinned petrels 2025.  Report to Department of Conservation, Conservation Services Programme.  Dunedin: Parker Conservation.  28 pp.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 12 August 2025