"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

A Manx Shearwater close to fledging at its burrow mouth, photograph by Jaclyn Pearson

Martyna Syposz (Department of Zoology, University of Oxford, South Parks Road, UK) and colleagues have published in the in the Journal of Avian Biology on fledging direction of Manx Shearwaters Puffinus puffinus.

The paper’s abstract follows:

“The first solitary migration of juvenile birds is difficult to study because of a low juvenile survival rates and sometimes long delays in return to the breeding grounds. Consequently, little is known about this crucial life event for many bird species, in particular the sensory guidance mechanisms facilitating the first migratory journey. Initial orientation during the first migration is a key measure to investigate these mechanisms. Here, we developed an assay to measure initial orientation as flight direction upon first take‐off in nocturnally fledging juvenile seabirds. We dorsally deployed a coloured LED on juvenile birds to allow researchers to observe the vanishing bearings of individuals as they flew out to sea. Additionally, we co‐deployed either a small Neodymium magnet or glass bead (control) on top of the bird's head to investigate the use of magnetoreception, previously unexplored in this early life stage.

We used this assay to observe the first flight of Manx shearwaters (Puffinus puffinus) and found that they did not orient towards their wintering ground straight after taking off. Further, we did not find an effect of the magnetic treatment on juveniles’ flight direction, though whether this is due to the birds not using magnetoreception, other salient cues being available or a lack of motivation to orient to the migratory beeline is unclear. We were, however, able to identify wind direction and topography as drivers of first flight direction in Manx shearwaters, which fledged with wind component between a crosswind and a tailwind and directed their maiden flight towards the sea and away from the land.

This novel assay will facilitate the study of the maiden flight of nocturnally fledging birds and will help advance the study of sensory guidance mechanisms underpinning migratory orientation in a wide range of taxa, including species which are traditionally challenging to study.”

Reference:

Syposz, M., Padget, O., Wynn, J., Gillies, N., Fayet, A.L. & Guilford, T. 2020.  An assay to investigate factors influencing initial orientation in nocturnally fledging seabirds.  Journal of Avian Biology doi.org/10.1111/jav.02613  doi.org/10.1111/jav.02613.

John Cooper, ACAP Information Officer, 21 November 2020