Gulls choose what to eat by watching humans, study suggests
It will take more than a bunch of signs declaring “do not feed the birds” to deter gulls from swooping down to pinch people’s snacks, a study has suggested.
Research on herring gulls at Brighton beach found that the birds can work out which kinds of scraps are worth snaffling by watching what humans are tucking into themselves.
When given a choice of crisp packets to peck at, gulls overwhelmingly went for the same colour bag that an experimenter was munching from as they filmed the encounters from several metres away.
“We’ve shown that adult gulls are able to pay attention to the behaviour of humans and apply that to their own foraging choices,” said Franziska Feist, a biologist and first author on the study at the University of Sussex.
“Given that the urbanisation of gulls is very recent, this ability must come from the gulls’ general smartness and behavioural flexibility.”
Scientists already knew that gulls prefer food that has been touched by people, but it was unclear how well they could draw on their observations of snacking humans to find similar bits of food while foraging.
In the latest work, Feist and her colleagues taped green (salt and vinegar) and blue (cheese and onion) packets of Walkers crisps to tiles and placed them a few metres from gulls on an otherwise clear patch of Brighton beach. The scientists then retreated 5 metres and filmed the birds’ behaviour. In some cases, the researchers simply looked at the camera, while in others they tucked into a green or blue bag of crisps.
When the scientists sat quietly without snacking, less than a fifth of gulls approached the crisp packets placed nearby. But when the researchers were snacking on crisps, 48% of the birds hopped over to check out the packets. Nearly 40% of such approaches ended with gulls pecking at the crisp packets, and of these, a hefty 95% were directed at the same colour packet as the scientist was eating from. “It is impressive because the evolutionary history of herring gulls wouldn’t have involved humans,” said Feist.
The work suggests that there is work to do to reduce tension between humans and urban gulls. The impact of “do not feed the birds” signs might, for example, be improved by adding “… and don’t let them see you eat, either”.
“It is likely that simply deterring the public from directly feeding gulls may not be enough,” Feist said. “They are still able to observe what we eat and that would inform their ability to target waste, litter and so on.”
Dr Madeleine Goumas, an expert on herring gulls at Exeter University who was not involved in the study, said: “We already know from previous research that gulls use information from people when they’re searching for food.
“This study shows that we aren’t only drawing gulls’ attention to where food is, but they also learn about the type of food we’re eating. Knowing this may have implications for how we reduce negative interactions between humans and gulls, as we seem to be inadvertently teaching gulls to exploit new food items.”
Details of the study are published in Biology Letters.