Lesser black-backed gulls from a Dutch island colony are deliberately steering clear of an offshore wind farm, despite expectations that they would be lured out by fishing boats and discarded bycatch. NIOZ ecologist Rosemarie Kentie fitted 58 of these birds with GPS transmitters to track their movements across the Zeeland coast, and the data revealed something surprising: the gulls almost universally avoided the wind farm, even when fishing—and the free meals that come with it—virtually disappeared on weekends.
The finding matters because it complicates how scientists think about the relationship between seabirds and offshore energy development. Wind farms, for all their environmental benefits, carve out chunks of foraging habitat for species that depend on the sea. Understanding what drives birds toward or away from these installations is crucial for writing better collision risk models—mathematical tools that predict how many birds will collide with turbine blades. Currently, those models are still crude, relying largely on guesswork, because counting dead seabirds at sea is nearly impossible.
Kentie and her collaborators—researchers from Waardenburg Ecology, the Flemish INBO, the University of Amsterdam, and other institutions—began with a logical hypothesis. The wind farm off Zeeland prohibits fishing, which creates both a problem and a puzzle: fewer flying hazards from boats, but potentially fewer feeding opportunities. Kentie suspected that gulls would weigh these tradeoffs differently depending on whether fishing vessels were working outside the farm's boundary. She even cross-referenced her GPS data with the Global Fishing Watch website, which tracks commercial fishing in real time, to test whether weekends—when fishing drops sharply—would bring more gulls into the wind farm. The birds, however, had other ideas. "There is something that makes them prefer not to enter the wind farms on weekends either," Kentie said. "No idea why, it fascinates me enormously."
What emerged from the tracking data was a portrait of remarkably individual creatures. Most gulls simply avoided the wind farm across all seasons. But some males—particularly during and after breeding season—ventured in regularly. Kentie noted that males typically spend more time at sea than females, who forage more on land, yet even this pattern held variation. One gull from Texel commutes 100 kilometers daily to forage in Amsterdam. Another, breeding on the Maasvlakte, makes the same distance trip each day to Utrecht. Each bird, it seems, has written its own foraging playbook.
The research underscores an uncomfortable paradox for seabirds at sea. Gulls face a notably high collision risk at offshore wind farms, partly because they fly at rotor height and partly because they are prone to looking downward as they hunt for fish, rendering them oblivious to rotating blades overhead. Yet despite being agile enough to snatch bread from the air on a ferry, this very hunting focus leaves them vulnerable. The study used Step Selection Analyses—a statistical method that compares where a bird could have gone with where it actually went—to determine that wind farm avoidance was consistent and deliberate.
Kentie is eager to deepen the work with even more granular observation. Current GPS tracking reveals location every 20 minutes but cannot show whether a gull is resting, hunting, or doing something else entirely. As offshore wind energy expands across European waters, these lesser black-backed gulls—which, along with terns and cormorants, represent the only seabirds that breed in the Netherlands—offer scientists a living laboratory for understanding how human infrastructure reshapes the wild places where birds have survived for generations.