Guided by infrasound?  A Black-browed Albatross leaves its South Atlantic breeding island for the open sea; photograph by Martin Collins

Samantha Patrick (School of Environmental Sciences, University of Liverpool, United Kingdom) and colleagues have published open access in the journal Frontiers in Ecology and Evolution on whether seabirds use low-frequency sound generated by waves and the coastline to navigate – and how to test their hypotheses.

The paper’s abstract follows:

“Seabirds are amongst the most mobile of all animal species and spend large amounts of their lives at sea. They cross vast areas of ocean that appear superficially featureless, and our understanding of the mechanisms that they use for navigation remains incomplete, especially in terms of available cues. In particular, several large-scale navigational tasks, such as homing across thousands of kilometers to breeding sites, are not fully explained by visual, olfactory or magnetic stimuli. Low-frequency inaudible sound, i.e., infrasound, is ubiquitous in the marine environment. The spatio-temporal consistency of some components of the infrasonic wavefield, and the sensitivity of certain bird species to infrasonic stimuli, suggests that infrasound may provide additional cues for seabirds to navigate, but this remains untested. Here, we propose a framework to explore the importance of infrasound for navigation. We present key concepts regarding the physics of infrasound and review the physiological mechanisms through which infrasound may be detected and used. Next, we propose three hypotheses detailing how seabirds could use information provided by different infrasound sources for navigation as an acoustic beacon, landmark, or gradient. Finally, we reflect on strengths and limitations of our proposed hypotheses, and discuss several directions for future work. In particular, we suggest that hypotheses may be best tested by combining conceptual models of navigation with empirical data on seabird movements and in-situ infrasound measurements”.

With thanks to Richard Phillips.

Reference:

Patrick, S.C., Assink, J.D., Basille, M, Clusella-Trullas, S., Clay, T.A., den Ouden, O.F.C., Joo, R., J., Zeyl, J.N., Benhamou, S., Christensen-Dalsgaard, J., Evers, L.G., Fayet, A.L., Köppl, C, Malkemper. E. Pascal, M., López, L.M., Padget, O., Phillips, R,A., Prior, M.K., Smets, P.S.M. & van Loon E.E. 2021.  Infrasound as a cue for seabird navigation.  Frontiers in Ecology and Evolution  doi.org/10.3389/fevo.2021.740027.

John Cooper, ACAP Information Officer, 03 December 2021

Sooty Albatrosses fly in unison off Marion Island, with Prince Edward Island on the horizon; photograph by Stefan Schoombie

Stefan Schoombie (FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa) and colleagues have published in the journal Polar Biology on aspects of the at-sea occurrence of globally Endangered Sooty Albatrosses Phoebetria fusca breeding on Marion Island in the southern Indian Ocean..

The paper’s abstract follows:

“Sooty Albatrosses (Phoebetria fusca; Endangered) are biennially breeding birds with successful breeders typically spending at least 15 months at-sea (‘sabbatical’) before returning to their breeding grounds on sub-Antarctic islands. Stable isotope analysis of feathers suggests that non-breeding adult Sooty Albatrosses moult in sub-tropical waters, north of the Sub-Tropical Front (STF). The Prince Edward Islands (Marion and Prince Edward) provide nesting grounds for ca 24% of the world’s Sooty Albatrosses. We tracked 20 adult Sooty Albatrosses from Marion Island with geolocators (GLS loggers) and satellite transmitters (PTT) during their non-breeding sabbaticals between 2008 and 2014. Stable isotope analysis also was performed on feathers collected from GLS-tracked birds upon device retrieval. Adult birds mostly remained within international waters in the southern Indian Ocean during their sabbatical period, splitting their time between sub-tropical and sub-Antarctic waters. Sooty Albatrosses were more active during the day on average but spent similar time in flight during full moon periods. Periods of reduced flight activity, measured by time on water, suggest that moulting occurs mainly around the STF. Breeding success influenced moult phenology, with unsuccessful birds moulting in late summer, immediately following a failed breeding attempt (Feb–Mar), whilst successful breeders moulted early the following summer (Oct–Dec). Failed breeders spent more time flying between breeding attempts than successful breeders, particularly whilst moulting. Our study identifies key areas utilised by non-breeding Sooty Albatrosses, which is critical to implement appropriate management strategies that may help population recovery of this endangered species.”

With thanks to Stefan Schoombie.

Reference:

Schoombie, S., Connan, M., Dilley, B.J., Davies, D., Makhado, A.B. & Ryan, P.G.. 2021.  Non-breeding distribution, activity patterns and moulting areas of Sooty Albatrosses (Phoebetria fusca) inferred from geolocators, satellite trackers and biochemical markers.  Polar Biology doi.org/10.1007/s00300-021-02969-3.

John Cooper, ACAP information Officer, 02 December 2021

At risk to House Mice.  A Grey-headed Albatross stands over its chick on Marion Island; photograph by John Dickens

A BirdLife South Africa Conservation Conversations webinar that was presented on the Gough and Marion Island mouse eradication projects on 23 November is now available on YouTube.

In the webinar Nini van der Merwe, Assistant Logistics & Procurement Manager, Gough Island Restoration Programme gives an update on the project and shares her experience of being part of the on-island team during the recently completed baiting operation to rid the island of its albatross-killing House Mice.  Anton Wolfaardt joins in at the end of Nini’s talk to share some of the progress with the Mouse-Free Marion Project, of which he is the Project Manager.

John Cooper, ACAP Information Officer, 01 December 2021

 
Black-browed Albatross at sea; artwork for ACAP by Peter Ward, Artists & Biologists Unite for Nature (ABUN)

 Francesco Ventura (Departamento de Biologia Animal, Universidade de Lisboa, Lisbon, Portugal) and colleagues have published open access in the journal Proceedings of the Royal Society B Biological Sciences on divorce in Black-browed Albatrosses Thalassarche melanophris in relation to environmental fluctuations.  The study concludes “Hence, in light of the dramatic extent of the current climatic changes, the environmentally driven disruptions of the breeding processes of socially monogamous populations might represent an overlooked consequence of global change, with repercussions on demography and population dynamics”.

The paper’s abstract follows:

“In many socially monogamous species, divorce is a strategy used to correct for sub-optimal partnerships and is informed by measures of previous breeding performance. The environment affects the productivity and survival of populations, thus indirectly affecting divorce via changes in demographic rates. However, whether environmental fluctuations directly modulate the prevalence of divorce in a population remains poorly understood. Here, using a longitudinal dataset on the long-lived black-browed albatross (Thalassarche melanophris) as a model organism, we test the hypothesis that environmental variability directly affects divorce. We found that divorce rate varied across years (1% to 8%). Individuals were more likely to divorce after breeding failures. However, regardless of previous breeding performance, the probability of divorce was directly affected by the environment, increasing in years with warm sea surface temperature anomalies (SSTA). Furthermore, our state-space models show that warm SSTA increased the probability of switching mates in females in successful relationships. For the first time, to our knowledge, we document the disruptive effects of challenging environmental conditions on the breeding processes of a monogamous population, potentially mediated by higher reproductive costs, changes in phenology and physiological stress. Environmentally driven divorce may therefore represent an overlooked consequence of global change.”

Read a popular account of the research here and listen to a radio interview about the publication with Graeme Elliot, Principal Science Adviser, Department of Conservation, New Zealand.

Reference:

Ventura, F., Pedro Granadeiro, J., Lukacs, P.M., Kuepfer, A. & Catry, P. 2021  Environmental variability directly affects the prevalence of divorce in monogamous albatrosses.  Proceedings of the Royal Society B Biological Sciences doi.org/10.1098/rspb.2021.2112.

John Cooper, ACAP Information Officer, 30 November 2021