Greening the City

Gulls prefer the city’s bright lights

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Typically associated with seaside holidays, seagulls have also become urban pests. Seagull colonies make a huge racket in the early hours of the morning, cover public benches, cars and the façades of buildings with their droppings, cause damage to roofs by ripping off bits of tarpaulin to make their nests, and during the breeding season even attack anyone who gets too close to their chicks. On top of that, even though the risk appears to be limited, they are potential carriers of diseases that can infect humans, such as salmonellosis. “The ability of the general public to put up with this nuisance depends not only of course on the bird density, but also on the urban environment,” points out Bernard Cadiou, an ornithologist at Bretagne Vivante (France). “No-one notices the populations of gulls on the Boulevard Haussmann in Paris due to the general background noise!”
Seagulls haven’t always been present in cities. “Before the 1970s, they only bred on islands. However, their numbers grew considerably due to the abundant supply of food, such as fishery waste and household refuse,” Cadiou explains. “When their natural environment became overpopulated, they set up colonies in coastal towns. They then started to fly upstream, and settled further and further inland.” In the 1980s and 1990s, the fisheries crisis and the closing of large waste dumps forced the gulls to turn to urban waste for food. “Today, island seagulls are starving, while their urban counterparts have never had it so good. In Brest (Brittany, France), seagulls have an average annual fertility of 1.5 fledglings per pair, as opposed to 0.3 for their fellows on the Molène Archipelago!” says Cadiou.
In 1993, Brest was the first city in France to organize operations to sterilize herring gull eggs, keeping the population in the city below a thousand pairs. Although these measures reduced noise levels and brought some relief to local residents, the colonies moved on after several unsuccessful attempts at breeding, which had the effect of spreading the invasion even further afield. “It’s better to act at the source by limiting the food resources to which the gulls still have easy access in the city,” Cadiou concludes.