Turbulent tidal flows show ‘dramatic effect’ on seabird foraging habits

University researchers from UK and Germany have conducted a study on turbulent tidal flows and their effect on foraging habits of seabirds which could potentially allow them to predict how species might respond to the increased future development of ocean renewable energy sites and climate change.

The study was conducted by researchers from Queen’s University Belfast and the University of Plymouth in the UK, and Bielefeld University in Germany.

In a first-of-its-kind study, scientists used drones to provide a synchronised bird’s eye view of what seabirds see and how their behaviour changes depending on the movement of tidal flows beneath them.

The researchers found that turbulent tidal flows, caused by natural or manmade ocean structures, have dramatic effect on foraging habits of seabrids.

The research focused on the wake of a tidal turbine structure set in a tidal channel – Strangford Lough in Northern Ireland – that has previously been identified as a foraging hotspot for terns.

Through a combination of drone tracking and advanced statistical modelling, it showed that terns were more likely to actively forage over vortices (swirling patches of water). However, eruptions of upwelling water (boils) ahead of the terns’ flight path prompted them to stay on course as they approached.

Writing in the Royal’s Society flagship biological research journal, Proceedings of the Royal Society B, the researchers say their findings offer a never-before-seen insight into how tidal turbulence can impact foraging behaviours.

They also say it potentially gives them the ability to predict how species might respond to environmental changes such as the increased future development of ocean renewable energy sites and climate change.

Lilian Lieber, research fellow at Queen’s University and the study’s lead investigator, said: “Our research highlights the importance of identifying changes in local flow conditions due to ocean energy structures which can change the occurrence, scale and intensity of localised turbulence in the water.

“Through a fantastic interdisciplinary collaboration, we were able to track prevalent flow features and seabirds on thus far unobtainable scales, shedding new light on tern foraging associations with turbulence. We found that terns were more likely to actively forage over vortices, while conspicuous upwellings provided a strong physical cue even at some distance, leading them to investigate such features. This research can help us predict seabird responses to coastal change”.