每日英語跟讀 Ep.816: Gulls observe humans to home in on tasty scraps
It’s the sort a sneaky trick only a gull would learn: by watching how people handle their food, the birds can work out when there are snacks to be had. Researchers found that herring gulls were more likely to peck at items left on the ground if humans had pretended to eat them first.
The study suggests that gulls take cues from human behavior to help them home in on tasty scraps in the rubbish people leave behind. “People don’t tend to think of wild animals as using cues from humans like this,” said Madeleine Goumas, a researcher at the University of Exeter. “It’s the kind of behavior that’s more often associated with domesticated animals or those kept in captivity.”
Goumas, who has become one of the more prominent gull researchers in Britain, reported last year that maintaining eye contact can deter seagulls from snatching food. In tests with bags of chips in seaside towns, she found that staring the birds out put them off their daring raids.
To follow up that work, Goumas wanted to see whether gulls pick up on subtle human cues to help them find their next meal. And so she set off to the Cornish towns of Falmouth, St Ives, Newquay and Penzance, and Plymouth in Devon, armed with shop-bought flapjacks in shiny blue wrappers, a supply of blue sponges, and a pair of dark glasses.
For the first experiment, Goumas donned the sunglasses and walked toward her chosen bird, carrying a bucket with a flapjack in each hand. When she was about 8m from the gull, she sat down, flipped the buckets over so they concealed the snacks, and pushed them out to her sides. She then lifted off the buckets, picked up one of the flapjacks, stood up and pretended to eat it. After 20 seconds, she put the flapjack back and retreated a safe distance.
Goumas, who wore the sunglasses to avoid deterring the birds with her gaze, recorded what the gulls did next. Out of 38 birds singled out for tests, 24 approached and pecked at the flapjacks. Of these, 19 — or 74 percent — pecked at the flapjack she had recently handled. The results suggest that the birds paid attention when she pretended to eat the snack.
To see whether the effect held true for other items, Goumas set off to different parts of the towns in search of more gulls. Once in place, she performed the same experiment but substituted the flapjacks for little blue sponges. This time, the gulls pecked both the handled and unhandled items roughly equally. “Seagulls have made an association between humans and food and the reason for that is probably that we’re not disposing of our food properly when we’ve finished it,” Goumas said. Details of the work are published in Royal Society Open Science.
Clashes between humans and herring gulls are believed to be on the rise as urban expansion encroaches on and overwhelms the birds’ traditional nesting grounds. While the birds seem abundant in seaside towns, the population in Britain fell 60 percent between 1969 and 2015, putting the birds on the UK’s red list of Birds of Conservation Concern.
“Whereas a lot of animals may not be able to live alongside humans and make use of urban environments, herring gulls seem to have been able to adapt and this is possibly one way they have become successful,” Goumas said. “Most seagulls don’t snatch food from people, they wait. If we don’t want to have gulls coming up to us and trying to get our food, we need to dispose of our food properly, and have bins that actually keep food inside them,” she added.
Source article: https://www.taipeitimes.com/News/lang/archives/2020/03/08/2003732262