While analysing the GPS tracks created by 22 Lesser Black-backed Gulls breeding in the port city of Zeebrugge, researchers from the University of Amsterdam accidentally ended up mapping a severe case of snack addiction.
The data showed that the birds were spending more time foraging on agricultural land and at landfills to the south of the port than they were scooping up their traditional diet of small fish and crustaceans at sea. Still, the team were surprised to find that roughly one third of the birds’ feeding trips were unusually long loops down to the industrial city of Moeskroen, 40 miles south of their nest sites. Some gulls were even flying down and back several times a day.
When one of the scientists went down to Moeskroen to investigate its particular charms, he found the gulls at a potato crisp factory that was dumping its discards outside in open-topped containers — an astonishing demonstration of the behaviour-warping allure of fried potatoes.