A White-capped Albatross breeding on Disappointment Island, photograph by Graham Parker

Graham Parker (Parker Conservation, Dunedin, New Zealand) and colleagues have produced a draft report for the New Zealand Department of Conservation’s Conservation Services Programme on their recent research on globally Near Threatened White-capped Albatrosses Thalassarche steadi in the Auckland Islands.

The report’s summary follows:

“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.”

Reference:

Parker, G.C., Osborne, J., Sagar, R., Schultz, H. & Rexer-Huber, K. 2024.  White-capped albatross population study, Disappointment Island 2024.  DRAFT Final report to the Conservation Services Programme, Department of Conservation. Dunedin:  Parker Conservation. 14 pp.

27 May 2024

Locations of Short-tailed Albatross breeding sites from the publication.  Note the Senkaku/Diaoyu/Tiaoyutai Islands are disputed territory

Masaki Eda (The Hokkaido University Museum, Sapporo, Japan) and colleagues have published open access in the journal Avian Conservation and Ecology on genetic aspects of two populations of Vulnerable Short-tailed Albatrosses Phoebastria albatrus

Access earlier publications by Masaki Eda on the genetics of Short-tailed Albatrosses

The paper’s abstract follows:

“When secondary contact occurs between allopatric sister species, several evolutionary consequences are expected, such as reinforcement of reproductive isolation, hybrid speciation, de-speciation, introgressive hybridization, or formation of a stable hybrid zone.  The Short-tailed Albatross (Phoebastria albatrus) is a vulnerable seabird that breeds mainly in Torishima, the Izu Islands, and two islets in the Senkaku Islands in the western North Pacific. Recent studies revealed that Short-tailed Albatross comprises two cryptic species (Senkaku-type and Torishima-type) that breed sympatrically on Torishima.  Ringed (hatched in Torishima) and unringed (probably hatched in the Senkaku Islands) birds mate in a mutually assortative manner at the Hatsunezaki colony (artificially established in 1995) on Torishima.  However, observations of some ringed–unringed pairs suggest possible hybridization between the two cryptic species.  To clarify the degree of hybridization, we analyzed microsatellite DNA and mitochondrial DNA control region 2 (CR2) sequences of chicks from Hatsunezaki and Tsubamezaki (original colony discovered in 1951) colonies and of unringed birds from Hatsunezaki. In general, both CR2 sequences and microsatellites revealed genetic differentiation between immigrants from the Senkaku Islands (unringed birds) and chicks hatched in Tsubamezaki.  These findings support the existence of two cryptic species.  Each chick obtained from four ringed–unringed parent pairs at Hatsunezaki displayed a high proportion of alleles from just a single population.  In contrast, some chicks in Tsubamezaki had a medium proportion of alleles from both populations.  Breeding unringed subadult plumage birds, which were probable immigrants from the Senkaku Islands, were observed in Hatsunezaki but not in Tsubamezaki.  Therefore, we propose that interspecific pairing occurred in the past but infrequently in recent generations on Torishima, suggesting historical reinforcement of reproductive isolation.  Further microsatellite DNA studies of chicks from Hatsunezaki are required to confirm whether reinforcement of reproductive isolation is achieved. Alternatively, nearly complete pre-mating isolation between the two species was established in the past, but the scarcity of Senkaku-type birds in Torishima has facilitated hybridization.”

Reference:

Eda, M., Izumi, H., Konno, S. Konno, M., Watanabe, Y. & F. Sato. 2023.  Evidence of historical pairing between two cryptic species of Short-tailed Albatross.  Avian Conservation and Ecology 18(1): 3.

23 May 2024

Pink-footed Shearwater, gouache watercolour for ACAP by ABUN artist, Griselle Chock, after a photograph by Peter Hodum

Ryan Carle (Oikonos-Ecosystem Knowledge, Santiago, Chile) and colleagues have published in the online journal Marine Ornithology on a breeding survey of the Vulnerable and ACAP-listed Pink-footed Shearwater Ardenna creatopus.

The paper’s abstract follows:

“Species population estimates are a fundamental component of conservation planning, but there are deficiencies in reliable data for many seabirds. The Pink-footed Shearwater Ardenna creatopus is a seabird that breeds on three islands worldwide, with the largest population on Isla Mocha, Chile. We aimed to update the breeding population estimate of Pink-footed Shearwaters on Isla Mocha, comparing results from design- and model-based estimation methods. We counted shearwater burrows in 220 randomly generated five-meter-radius plots across pre-defined strata on Isla Mocha. We estimated total number of burrows using area-based extrapolation (design-based method), and separately using a model predicting burrow density based on habitat (model-based method). We multiplied burrow abundance estimates by burrow occupancy for final population estimates. The stratum-area-weighted burrow density estimate for the 15.8 km² study area was 0.0106 burrows·m^-2 (standard error [SE] = 0.0030). The average island-wide proportion of occupied burrows was 0.758 (standard deviation [SD] = 0.121). The design-based method estimated 168 209 burrows (95% confidence interval [CI] = 74 715-261 704, coefficient of variation [CV] = 0.28), and 127 503 breeding pairs (95% CI = 87 610-167 395). The model-based method estimated 233 436 burrows (95% CI = 151 237-332 179, CV = 0.19) and 181 859 breeding pairs (95% CI = 95 773-267 945, CV = 0.24). These population estimates are greater than previous estimates for Isla Mocha, whose means ranged from 19 440-42 095 breeding pairs. Because our study design differed from those used to generate previous estimates, our estimate should be considered a stand-alone result rather than an increase in the breeding population. Because of the low fit of the model-based result, the design-based result may be a more reliable estimate to use for species management efforts. Based on our estimate, approximately 90% of the Pink-footed Shearwater world population breeds on Isla Mocha, and with its restriction to only three breeding localities world-wide, the species remains vulnerable. The full manuscript in Spanish can be found in Appendix 1, available on the website.”

Reference:

Carle, R.D, Varela, T., Colodro, V., Clark-Wolf, T., Felis, J., Hodum, P., Astete Castillo, F.J. & López, V. 2024.  Breeding population size of the Pink-footed Shearwater Ardenna creatopus on Isla Mocha, Chile.  Marine Ornithology 52: 85-96.

22 May 2024

A Galápagos Petrel on its burrow nest, photograph from the Galápagos National Park Directorate

The Galápagos Petrel Pterodroma phaeopygia, endemic to Ecuador’s Galapagos Islands, is Critically Endangered.  The species has been listed by the Convention on the Conservation of Migratory Species of Wild Animals (CMS) in Annex 1 since 1979 and has been proposed in the past for listing by the Agreement on the Conservation of Albatrosses and Petrels (ACAP).  In 2019 the First International Meeting for the Conservation of the Galápagos Petrel (Primera Reunión Internacional para la Conservación del Petrel de Galápagos) was held in Puerto Ayora, Santa Cruz Island, Galapagos.  The purpose of the meeting, which ACAP attended, was to bring together researchers, governmental agencies and non-profit groups with the shared interest of coordinating future conservation actions for Ecuador’s endemic petrel and to draft an action plan (click here).

Galápagos Petrel in flight, photograph by Eric VanderWerf

The Galápagos Petrel is known to breed on five islands: Floreana, Isabela, San Cristóbal, Santa Cruz and Santiago.  Threats to the species include non-native species, both flora and fauna, and encroachment of human activities.  To address these threats the environmental NGO Galápagos Conservancy has partnered with the Galápagos National Park Directorate to implement conservation projects on three of the breeding islands: Isabela, Santa Cruz and Santiago (click here for a summary of the plans for each island).  ACAP Latest News has previously reported on the recent effort to eradicate feral cats and rodents on Floreana.

A downy Galápagos Petrel in its burrow, photograph from the Galápagos National Park Directorate

The Galápagos Conservancy writes: “With community support and international collaboration, we can ensure a future where these majestic birds continue to soar through the night skies of the Galápagos.  Management measures and decisions based on technical criteria, thanks to studies conducted, will also be critical to the conservation of this species.  The complex process of protecting this species demands constant effort, and we appreciate the support of our many donors, whose generosity supports the conservation actions implemented by our organization.  Every action, no matter how small, counts in this fight for the survival of the Galápagos Petrel.”

ACAP held a one-day workshop on gadfly petrels of the genera Pterodroma and Pseudobulweria and other small petrels in Wellington, New Zealand in 2017, prior to the 10th Meeting of its Advisory Committee (AC10).  Read the workshop report here.

John Cooper, Emeritus Information Officer, Agreement on the Conservation of Albatrosses and Petrels, 21 May 2024