Gulls are adapting to human environments in remarkable ways, but a new study has found their survival may still be at risk.
Scientists from the British Trust for Ornithology (BTO) have tracked three gull species on the Isle of May, off Scotland’s east coast, to understand how these birds forage for food and how competition and habitat change could affect their future.
The research, which involved fitting GPS trackers to nesting gulls, aimed to reveal whether closely related species search for food in different places and if they’re increasingly relying on human-dominated landscapes.
The team, who published their findings in the journal Ecology and Evolution, focused on great black-backed gulls, lesser black-backed gulls and herring gulls – all species of conservation concern in the UK.
How far do gulls travel to survive?
The study found that while the three species often overlapped in the areas they used, there were clear differences in how and where they foraged.
Great black-backed gulls, the largest of the three species studied and the world’s biggest gull, stayed relatively close to the colony. Their size may give them a competitive edge, say the researchers, allowing them to dominate smaller gulls.
Herring gulls, often spotted along the coast or in seaside towns, also remained fairly local, favouring harbours and landfill sites.
Lesser black-backed gulls, however, were found to travel much further afield. These more wide-ranging birds frequently ventured inland to agricultural areas in search of food, though they too visited landfill sites and coastal spots.
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Changing feeding habits
While these findings highlight the flexibility of gulls, they also expose a growing problem. As traditional food sources such as fish discards decline and landfill sites close or are better managed, gulls are being forced to adapt once again. This shift may push them towards lower quality habitats, increasing the risk of food shortages and competition both within and between species.
"We know that gulls can be very adaptable, but not all food sources meet their needs,” says Dr Nina O’Hanlon, senior research ecologist at BTO Scotland. “When forced into suboptimal habitats, they may not find enough food to feed their chicks, or they may experience greater competition with other gulls searching for the same limited food.
“Our findings have allowed us to better understand how the foraging behaviours of different gull species could be impacted by habitat change, or how these birds might interact more with humans in future.”
The study not only sheds light on the pressures these seabirds face, but also offers valuable insight for conservation efforts and managing human-wildlife interactions.
Find out more about the study: Partial Niche Partitioning in Three Sympatric Gull Species Through Foraging Areas and Habitat Selection
Top image: Great black-backed gull. Credit: Getty
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