Lesser black-backed gulls from the colony at the Dutch island Neeltje Jans appear to avoid the wind farm off the Zeeland coast, with the exception of some males. NIOZ ecologist Rosemarie Kentie and her colleagues suspected the gulls were attracted by fishing boats outside the windfarm, and their bycatch thrown overboard. This turned out not to be the case: even during weekends, when there is little fishing, the birds rarely visit the wind farm. They published their findings in the Journal of Animal Ecology. "Why the gulls still avoid the wind farm fascinates me immensely."
Rosemarie Kentie fitted 58 lesser black-backed gulls (Larus fuscus) with GPS transmitters to see if and when they entered the wind farm off the Zeeland coast. She wanted to know whether these birds found the wind farm attractive or, on the contrary, avoided it. Before, during and after the breeding season, they were found to spend more time around fishing vessels than in the wind farm, where fishing is prohibited. Understandably so: near fishing vessels, they can feed on discarded by-catch.
Every gull has its own habits
But there was quite a difference between individuals. Some males, in fact, were attracted to the wind farm frequently during and after the breeding season. 'Males are generally out at sea more often than females, who tend to forage for food on land,' says Kentie. 'But each individual also has its own habits, which is fascinating. There's a gull from Texel known to fly back and forth to Amsterdam every day, 100 kilometres away. And a gull that breeds on the Maasvlakte and goes to Utrecht every day, at a comparable distance.'
No idea why
Kentie, who collaborated with ecologists from Waardenburg Ecology , the Flemish INBO , IBED at the University of Amsterdam, Deltamilieu Projecten en Buijs Eco Consult , wondered whether the fact that they were attracted to the wind farm to a greater or lesser extent was linked to fishing outside the farm. 'With the Global Fishing Watch website, you can see where and when fishing takes place. We linked our data to this.' She had expected that the gulls' behaviour would be easily explained by the fishing data. There is far less fishing at the weekend than on weekdays, so surely more gulls would fly into the park. 'But they didn't. There is something that makes them prefer not to enter the wind farms at the weekend either. No idea why, it fascinates me enormously.'
Collision models
Offshore wind farms pose a risk to seabirds. On the one hand, they might be attractive precisely because fishing is not permitted there and certain fish are abundant. On the other hand, the rotating blades pose a risk. Some species avoid the wind farms – meaning that such a vast wind farm effectively takes a chunk out of their foraging area.
Funders of the research were Eneco, wind farm owner, and Rijkswaterstaat, responsible for research the effects of wind at sea. They want to make the Collision Risk Models more realistic: models that estimate how many birds of different species fly into the blades of wind turbines. Kentie: 'We still don't really know how many collisions there are at sea. On land you can find the carcasses, at sea you cannot. And with cameras you cannot see clearly what happens at night or in bad weather.'
Relatively high risk
Based on counts of collision victims on land and knowledge of their behaviour, gulls are at relatively high risk. 'This is partly due to the height at which they fly, namely at the height of the rotors. On the one hand, they are very agile; on the ferry to Texel, you sometimes see them skilfully catching bread out of the air. But when they look down to search for fish, they cannot see what is happening in front of them.'
Scientific publication
Kentie and colleagues published their research on June 9 in the Journal of Animal Ecology. They used an interesting method to analyse the locations of the gulls: Step Selection Analyses. 'That's a beautiful statistical model that compares location where it could go wit locations where it actually went. 'Suppose there is a 50 per cent chance that a gull will provide the next GPS location from the wind farm – in other words, the next "step" – but that none of them do so, time and time again; then the wind farm is clearly being avoided.'
Even more detailed
This GPS research does not show what a gull is doing – you only see where it is every twenty minutes. 'We don't know whether they were, for example, resting at the base of a wind turbine or looking for food.' Along with terns and cormorants, gulls are the only seabirds that breed in the Netherlands; Kentie can't wait to conduct even more detailed research into these fascinating birds that live both in the city and at sea.
The article 'Offshore wind farm avoidance by a discard-feeding seabird is independent of local fishing activity' by Rosemarie Kentie Rob S.A. van Bemmelen, Judy Shamoun-Baranes, Eric W.M. Stienen, and Ruben C. Fijn., was published on 9 June 2026 in Journal of Animal Ecology.
