Gustavo Jiménez-Uzcátegui (Charles Darwin Research Station, Puerto Ayora, Galápagos, Ecuador) and colleagues have published in the open-access journal Marine Ornithology on the foraging ecology of three species of Galapagos seabirds studied by stable isotope analysis, including the globally Critically Endangered Waved Albatross Phoebastria irrorata.

The paper’s abstract follows:

“The Galápagos Penguin Spheniscus mendiculus, Flightless Cormorant Phalacrocorax harrisi, and Waved Albatross Phoebastria irrorata are endemic to Islas Galápagos. They are known to feed on different prey (including crustaceans, cephalopods, and/or several species of epipelagic and benthic fish), in accordance with different foraging strategies. In this work, we used stable-isotope analysis of carbon and nitrogen to corroborate available information on habitat use (δ¹³C) and trophic position (δ¹⁵N). Feather samples from the three species were collected in six different areas prior to the 2011 and 2012 breeding seasons. Results showed differences in foraging strategies between Galápagos Penguins and the other two species (δ¹³C and δ¹⁵N, P < 0.01). The Flightless Cormorant and Waved Albatross showed similar proportions of δ¹³C (P = 0.07), but they occupied different trophic levels (δ¹⁵N, P < 0.01).”

Statue of a Waved Albatross in Puerto Ayora, Santa Cruz, Galapagos; photograph by John Cooper

Reference:

Jiménez-Uzcátegui, G., Vaca, L., Cotín, J., García, C., Costales, A., Sevilla, C., & Páez-Rosas, D. 2019.  Using referential values of δ13C and δ15N to infer the foraging ecology of Galápagos seabirds.  Marine Ornithology 47: 5-10.

John Cooper, ACAP Information Officer, 09 November 2018

Tyler Clark (Institute of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, Scotland, UK) and colleagues have published open access in the ornithological journal Ibis on aspects of the burrows of Sooty Shearwaters Ardenna grisea.

The paper’s abstract follows:

“The Sooty Shearwater Ardenna grisea, an abundant but declining petrel, is one of many seabird species that construct breeding burrows, presumably because these confer protection from predators and the elements. Little is known about the causes of variation in Sooty Shearwater burrow architecture, which can differ markedly both within and between breeding sites. We hypothesize that varies in response to habitat type and competition for space. To address these hypotheses, we recorded Sooty Shearwater burrow dimensions on Kidney Island, the largest Sooty Shearwater colony in the Falkland Islands, South Atlantic, and modelled these as functions of burrow density (a proxy for competition) and habitat indices. Our models suggest that Sooty Shearwaters burrow further underground in response to competition for breeding space, and that soil underlying dense tussac grass Poa flabellata is more easily excavated than other substrates, indicating how vegetation restoration could aid the conservation of this species.”

Reference:

Sooty Shearwater, photograph from the West Coast Penguin Trust

Clark, T.J., Bonnet-Lebrun, A.-S., Campioni, L., Catry, P. & Wakefield, E. 2018.  The depth of Sooty Shearwater Ardenna grisea burrows varies with habitat and increases with competition for space.  Ibis doi.org/10.1111/ibi.12631.

John Cooper, ACAP Information Officer, 08 November 2018

Anne-Sophie Bonnet-Lebrun (Department of Zoology, University of Cambridge, UK) and colleagues have published open access in the journal Marine Biology on individual specialisation in at-sea distribution of satellite-tracked Black-browed Albatrosses Thalassarche melanophris and Grey-headed Albatrosses Thalassarche chrysostoma.

The paper’s abstract follows:

“Many predictive models of spatial and temporal distribution (e.g. in response to climate change or species introductions) assume that species have one environmental niche that applies to all individuals. However, there is growing evidence that individuals can have environmental preferences that are narrower than the species niche. Such individual specialization has mainly been studied in terms of dietary niches, but a recent increase in the availability of individual movement data opens the possibility of extending these analyses to specialisation in environmental preferences. Yet, no study to date on individual specialisation has considered the environmental niche in its multidimensionality. Here we propose a new method for quantifying individual specialisation in multiple dimensions simultaneously. We compare the hypervolumes in n-dimensional environmental niche space of each individual against that of the population, testing for significant differences against a null model. The same method can be applied to a 2-dimensional geographic space to test for site fidelity. We applied this method to test for individual environmental specialisation (across three dimensions: sea surface temperature, eddy kinetic energy, depth) and for site fidelity among satellite-tracked black-browed albatrosses (Thalassarche melanophris) and grey-headed albatrosses (Thalassarche chrysostoma), during chick-rearing at South Georgia. We found evidence for site fidelity in both species and of environmental specialisation among individual grey-headed but not black-browed albatrosses. Specialisation can affect the resilience of populations affected by natural and anthropogenic changes in the environment, and hence has implications for population dynamics and conservation.”

Grey-headed Albatross, photograph by Kirk Zufelt

Reference:

Bonnet-Lebrun, A.-S., Phillips, R.A., Manica, A & Rodrigues, A.S.L. 2018.  Quantifying individual specialization using tracking data: a case study on two species of albatrosses.  Marine Biology doi.org/10.1007/s00227-018-3408-x.

John Cooper, ACAP Information Officer, 07 November 2018

The last rehabilitated Newell’s Shearwater or ʻAʻo Puffinus newelli carrying a back-mounted satellite tag was released to sea from the Hawaiian island of Kauai on 18 October. The release represents the culmination of a project started in 2014 by the Kaua'i Endangered Seabird Recovery Project, the Save our Shearwaters (SOS) programme of the Kauai Humane Society and the U.S. Geological Survey that has resulted in 53 Newell's Shearwaters being tagged since then.  There are currently nine globally Endangered Newell’s Shearwaters transmitting their locations back to the tagging project.  The goal of the project is to compare birds that have been grounded by light pollution on the island and subsequently rehabilitated against wild-tagged 'controls'.

Most of the tagged fledglings this year came from the rugged mountains of the Upper Limahuli Preserve on Kauai.  Following tagging within the preserve chicks were returned to their burrows to fledge naturally.  Three, including the very last one tagged, were “fallout” fledglings that had first been rehabilitated by Save our Shearwaters.  However, over the five years of the project most of the birds satellite-tagged (38) were SOS “rehabs”.  Except for four adults, all those tagged were chicks or fledglings. To date, the longest transmission period recorded  is 111 days, with tagged birds recorded flying thousands of kilometres to the south-west of Kauai.

 A Newell's Shearwater fledgling undergoing rehabilitation is ready for release, with its back-mounted satellite tag in place

 Satellite tags ready for deployment in the Upper Limahuli Preserve

Last of 53!  A rehabilitated Newell's Shearwater fledgling gets released on Kauai's shore.  Note the tag's aerial projecting from the bird's back

André Raine, Kaua'i Endangered Seabird Recovery Project, writes to ACAP Latest News: “we are planning to publish the results after the final transmissions of this season.  This year represents the final cap to the project, so afterwards we can analyse and publish.”

The tagging project has been funded by the St Regis Princeville Resort on Kauai (via Earthjustice and the American Bird Conservancy) and the Kauai Island Utility Cooperative.

 Read more here.

With thanks to André Raine and the KESRP and SOS Facebook pages for information and photographs.

John Cooper, ACAP Information Officer, 06 November 2018