Infrasound as a Cue for Seabird Navigation

A schematic representation of the marine infrasonic wavefield. The ocean produces continuous acoustic background noise (i.e., microbaroms and surf; depicted in blue). Microbaroms can propagate over long distances downwind (i.e., from east to west) in the stratospheric waveguide. In the upwind direction, microbaroms are not guided and propagate toward space. The wind direction changes seasonally. Surf infrasound is generated near coastlines and does not propagate over long distances. Transient acoustic signals (red) also occur in the marine environment, e.g., following an underwater earthquake. These vibrations can couple into the atmosphere. Besides the acoustic signals, the wavefield also consists of turbulence, which may mask signals of interest. Array processing techniques can be used to detect coherent acoustic waves in a turbulent atmosphere.
SC Patrick, JD Assink, M Basille, S Clusella-Trullas, TA Clay, OFC den Ouden, R Joo, JN Zeyl, S Benhamou, J Christensen-Dalsgaard, LG Evers, AL Fayet, C Köppl, EP Malkemper, LM Martín López, O Padget, RA Phillips, MK Prior, PSM Smets, EE van Loon

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.

Bibliografische gegevens

SC Patrick, JD Assink, M Basille, S Clusella-Trullas, TA Clay, OFC den Ouden, R Joo, JN Zeyl, S Benhamou, J Christensen-Dalsgaard, LG Evers, AL Fayet, C Köppl, EP Malkemper, LM Martín López, O Padget, RA Phillips, MK Prior, PSM Smets, EE van Loon. Infrasound as a Cue for Seabird Navigation
Journal: Frontiers in Ecology and Evolution, Volume: 9, Year: 2021, doi: 10.3389/fevo.2021.740027

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