A Manx Shearwater among the flowers, photograph by Chris Perrins

Christopher Perrins (Department of Zoology, University of Oxford, UK) and colleagues have published open access in the annual journal Seabird on a census of Manx Shearwaters Puffinus puffinus on three islands off the coast of Wales.

The paper’s abstract follows:

“We present the results of a census of the Manx Shearwaters Puffinus puffinus nesting on the three Pembrokeshire islands of Skomer, Skokholm and Midland (formerly Middleholm), Pembrokeshire, undertaken in 2018. The breeding population estimates were largely in line with those made in 2011–2013, but differed markedly from 1998; this difference seems to be due to the different methods used in 1998 rather than any marked change in population size. Despite attempts to refine the estimation of response rate to call playback, the error of the population estimates remains large, illustrating the logistical and analytical challenges of making seabird censuses using call playback. Nonetheless, the population estimates are large and the spatial distribution of occupied burrows is consistent between censuses, and thus Wales may hold more than half of the world’s breeding population of Manx Shearwaters.”

Reference:

Perrins, C., Padget, O., O’Connell, M., Brown, R., Büche, B., Eagle, G., Roden, J., Stubbings,^, E. & Wood,^, M.J. 2019.  A census of breeding Manx Shearwaters Puffinus puffinus on the Pembrokeshire Islands of Skomer, Skokholm and Midland in 2018.  Seabird 32: 106-118.

John Cooper, ACAP Information Officer, 26 November 2020

 "The left pair is the Torishima-type Short-tailed Albatross, while the two on the right are the Senkaku-type Short-tailed Albatross. This is the first case of cryptic species found in an endangered bird species" - from the Endangered Species Research Facebook Page

Masaki Eda (Hokkaido University Museum, Sapporo, Japan) and colleagues have published open access in the journal Endangered Species Research on whether the Short-tailed Albatross Phoebastria albatrus should be two species, with consequent implications for the threatened status of the two cryptic populations.

The paper’s abstract follows:

“The occurrence of cryptic species within a threatened taxon is rare, but where they do occur, understanding species boundaries is essential for planning an effective conservation strategy. The short-tailed albatross Phoebastria albatrus is a Vulnerable seabird that mainly breeds on Torishima and the Senkaku Islands in the western North Pacific. Although it has been tacitly regarded as a single management unit with 2 breeding sites, the species is known to comprise 2 genetically separated populations (Senkaku-type and Torishima-type). However, morphological examination of birds from both populations has not been conducted owing to the difficulty in accessing the Senkaku Islands. In this study, we examined the morphological differences between immigrants from the Senkaku Islands to Torishima (Senkaku-type) and native birds on Torishima (Torishima-type) and found significant differences in morphological characteristics between the 2 bird types. In general, Torishima-type birds were larger than Senkaku-type birds, whereas Senkaku-type birds had relatively longer beaks. Based on the morphological differences found in this study as well as genetic and ecological differences revealed in previous studies, we believe that Senkaku- and Torishima-type birds should be classified as different cryptic species. To the best of our knowledge, this is the first case of cryptic species being identified in a threatened avian species.”

Reference:

Eda, M., Yamasaki, T., Izumi, H., Tomita, N., Konno, S.,Konno, M., Murakami, H. & Sato, F. 2020.  Cryptic species in a Vulnerable seabird: short-tailed albatross consists of two species.  Endangered Species Research doi.org/10.3354/esr01078 doi.org/10.3354/esr01078.

John Cooper, ACAP Information Officer, 25 November 2020

A Tristan Albatross chick, photograph by Tom McSherry

It has been another poor breeding season for the beleaguered Tristan Albatross Diomedea dabbenena on the United Kingdom's Gough Island in the South Atlantic.  Last month the outgoing and incoming field teams working for the Gough Island Restoration Programme (GIRP) joined up to undertake the annual count of chicks of the near-endemic and Critically Endangered species across the whole island.  A total of 569 chicks was counted that had survived - so far – the mainly winter depredations of the introduced House Mouse.  A few more chicks would be expected to die before fledging occurs around year end.

Ready for the count: the outgoing and incoming GIRP field teams at the helipad on Gough Island

The October count compares to the 1528 nests containing incubating birds counted back in January.  Based on these totals overall breeding success is 37.2%.  This means that only a little over a third of the breeding pairs will have successfully fledged a chick by season end.  GIRP reports that breeding success (as has been usual over two decades of study) varied across the island, with some count areas being as low as 18.7%, with the highest at 60.9%.  The overall average, once again, compares extremely poorly with those of other great albatrosses of the genus Diomedea on rodent-free islands - where a breeding success of 65-70% (around two thirds) is normal.

Attacked by mice overnight, this study colony Tristan Albatross chick died soon afterwards, photograph by Karen Bourgeois & Sylvain Dromzee

Last year’s plan to eradicate the island’s mice had to be cancelled due to restrictions on international travel as a consequence of the COVID-19 pandemic.  A decision is awaited by GIRP as to whether another attempt will be made in 2021 (click here).

John Cooper, ACAP Information Officer, 24 November 2020

Wandering Albatross breeding on Heard Island: a top predator in the Southern Ocean; photograph by the late Gavin Johnstone

Sophie Bestley (Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia) and colleagues review open access in the journal Frontiers in Ecology and Evolution on the roles of seabirds and marine mammals in Antarctica and the Southern Ocean.  The study forms a contribution to the first Marine Ecosystem Assessment for the Southern Ocean (MEASO) of the Scientific Committee on Antarctic Research (SCAR).  "The primary aim of MEASO is to assess the risks to Southern Ocean marine ecosystems from climate change and related change processes."

The paper’s abstract follows:

The massive number of seabirds (penguins and procellariiformes) and marine mammals (cetaceans and pinnipeds) - referred to here as top predators - is one of the most iconic components of the Antarctic and Southern Ocean. They play an important role as highly mobile consumers, structuring and connecting pelagic marine food webs and are widely studied relative to other taxa. Many birds and mammals establish dense breeding colonies or use haul-out sites, making them relatively easy to study. Cetaceans, however, spend their lives at sea and thus aspects of their life cycle are more complicated to monitor and study. Nevertheless, they all feed at sea and their reproductive success depends on the food availability in the marine environment, hence they are considered useful indicators of the state of the marine resources. In general, top predators have large body sizes that allow for instrumentation with miniature data-recording or transmitting devices to monitor their activities at sea. Development of scientific techniques to study reproduction and foraging of top predators has led to substantial scientific literature on their population trends, key biological parameters, migratory patterns, foraging and feeding ecology, and linkages with atmospheric or oceanographic dynamics, for a number of species and regions. We briefly summarize the vast literature on Southern Ocean top predators, focusing on the most recent syntheses. We also provide an overview on the key current and emerging pressures faced by these animals as a result of both natural and human causes. We recognize the overarching impact that environmental changes driven by climate change have on the ecology of these species. We also evaluate direct and indirect interactions between marine predators and other factors such as disease, pollution, land disturbance and the increasing pressure from global fisheries in the Southern Ocean. Where possible we consider the data availability for assessing the status and trends for each of these components, their capacity for resilience or recovery, effectiveness of management responses, risk likelihood of key impacts and future outlook.”

With thanks to Richard Phillips.

Bestley, S. et al. 2020.  Marine Ecosystem Assessment for the Southern Ocean: seabirds and marine mammals in a changing climate.  Frontiers in Ecology and Evolution doi: 10.3389/fevo.2020.566936.

John Cooper, ACAP Information Officer, 23 November 2020