Disrupted Skies: How Offshore Wind Farms Alter Flight Behavior of Breeding Seabirds

Area of Science:

• Marine Ecology
• Avian Behavior
• Renewable Energy Impacts

Background:

• Offshore wind farms are expanding globally for climate mitigation.
• Seabird responses to wind turbines, particularly flight route alteration and energetic costs near colonies, are not fully understood.
• Collision risk is studied, but evasive behavior and meso-avoidance require further investigation.

Purpose of the Study:

• To investigate flight responses of breeding Bridled Terns to offshore wind turbines.
• To quantify how turbines affect flight traits like redirection, speed, and altitude.
• To assess avoidance behavior using proximity-based and direction-sensitive metrics at near-colony and breeding-range scales.

Main Methods:

• Utilized high-resolution (1-s intervals) and lower-resolution (1-h intervals) satellite tracking data of Bridled Terns.
• Quantified within-trajectory flight traits (redirection, turns, speed, altitude) in relation to turbine exposure.
• Analyzed flight behavior based on alignment with turbine directions, proximity, and location (inside/outside wind farms), controlling for environmental variables.

Main Results:

• Bridled Terns exhibited increased mean redirection and lower flight altitude when flight paths aligned with turbine directions from the colony.
• Flight behavior was not significantly affected by turbine proximity or whether birds were inside or outside wind farms.
• Findings suggest localized, direction-dependent route alteration rather than simple distance-dependent avoidance.

Conclusions:

• Offshore wind farms can influence seabird movement by inducing localized, direction-specific flight path adjustments.
• Movement-context and within-trajectory metrics are valuable for assessing wind farm impacts on avian behavior.
• Understanding these nuanced responses is crucial for effective mitigation strategies in offshore wind development.