Researchers Use Drones to Reveal How Turbulent Tidal Flows Affect Seabirds' Foraging Behaviors

Turbulence caused by natural coastal features and manmade ocean systems has a significant impact on seabird foraging behavior, according to new studies.

Scientists from the United Kingdom and Germany used drones in a first-of-its-kind analysis to have a coordinated bird's eye view of what seabirds see and how their behavior changes when tidal flows under them pass.

The study was based on the wake of a tidal turbine structure installed in a tidal channel-Strangford Lough in Northern Ireland-that had previously been known as a tern foraging hotspot.

Seabirds React to Tidal Flows

It was discovered that terns were more likely to deliberately forage over vortices using a combination of drone monitoring and sophisticated statistical modeling (swirling patches of water).

However, the terns were forced to keep on course as they approached due to upwelling water (boils) ahead of their flight route.

The researchers believe their results provide a never-before-seen insight into how tidal turbulence can affect foraging activities in Proceedings of the Royal Society B, the Royal Society's flagship biological research journal.

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Practical Application of the Study

They also claim it will help them foresee how organisms would respond to environmental trends such as the expanded production of ocean green energy sites in the future and climate change.

Researchers from Queen's University Belfast, the University of Plymouth (UK), and Bielefeld University collaborated on the analysis (Germany).

"Our research emphasizes the importance of understanding variations in local flow conditions due to ocean energy systems, which can affect the occurrence, size, and severity of localized turbulence in the water," said Dr. Lilian Lieber, Bryden Centre Research Fellow at Queen's and the study's lead investigator.

Going Bigger

We could map prevalent flow characteristics and seabirds on previously unattainable scales thanks to a wonderful interdisciplinary partnership, throwing new light on tern foraging interactions with turbulence. We discovered that terns were more likely to deliberately forage over vortices. Visible upwellings offered a clear physical signal, causing them to explore specific features even at a distance. This study could aid in forecasting seabird responses to coastal change."

Professor Roland Langrock, a co-investigator and a professor of statistics and data analysis at Bielefeld University, said: "We now have these exact animal activity data, which enables us to study behavioral mechanisms at essentially arbitrarily fine scales of animal decision-making, which is extremely exciting. Our project's interdisciplinary nature provides a significant contribution to the evolving field of high-throughput movement ecology, including some new statistical challenges."

Dr. Alex Nimmo-Smith, an Associate Professor of Marine Physics at Plymouth University, led the technical creation of a method for automatically and accurately monitoring terns using machine learning and mapping the underlying turbulent characteristics.

He continued, " "The drone gave us a bird's eye view, helping us to follow the terns' extremely dispersed foraging activity and their close interaction with specific flow features. Powerful tidal currents produce upwelling boils and swirling vortices, which can carry possible prey (such as small fish) to the water surface and catch them there. As a result, these physical mechanisms provide terns with foraging opportunities."

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