Why do gulls steal our food? Scientists experimented with French fries to find out.
Gulls are often seen as intruders in our daily lives. But researchers are discovering what really motivates them—and strategies to keep them away from your lunch.
Animal ecologist Laura Kelley began studying gulls because she had a six-month-old baby. The child didn’t encourage her, exactly, but when she took a faculty position at the Cornwall campus of the University of Exeter, doing her usual field work on bowerbirds in Australia wasn’t practical. Gulls, though, were everywhere.
It’s hard to ignore gulls in Cornwall. They are ubiquitous and noisy, nesting on roofs of houses and flying over the street. As in many coastal places, people there have wildly different opinions about gulls, from loving them as symbols of the sea to calling them “rats with wings.” The birds pester beachgoers and swipe French fries at park benches.
Gulls thus have a bit of a PR problem—they can be more in your face than many of us would like, especially when consoling a child holding an empty ice cream cone after a gull has dive-bombed it. The droppings on cars and city benches can be hard to take. And most of us even get their names wrong.
(The astonishing superpowers of nature’s most unloved animals.)
Aiming to understand whether gulls truly deserve the bad rap, Kelley teamed up with her University of Exeter colleague Neeltje J. Boogert, who also had a young family and was looking for local research on animal behavior. As a behavioral ecologist myself, I became interested in their efforts while working on a book about outsider animals, or species, including gulls, that that are often seen as intruders in our daily lives.
“We do have to share our environment with these animals. They were here first,” Kelley argues. “So if we can find a way to coexist, so much the better.”
Their recent research—and that of others in the field—has offered gulls some redemption from their piratical reputation. It has also opened a window into how animal minds work, why one gull isn’t like the next, and how we can learn to live with urban wildlife.
Some gulls steal your food—but not all of them
The first thing you need to know about gulls is that most people get their names wrong. Ornithologists and birders never use the designation “seagull”—it’s just gull, period. That terminology reflects the cosmopolitan distribution of the birds—many species spend most of their time far from the ocean, and many are also equally at home in cities and remote clifftops. Over 50 species occur, and they are found on every continent, including Antarctica.
But back to the question of gulls stealing your food. Like it or not, taking food from other species is a gull signature move. Many gulls are what are termed kleptoparasites, animals that take food from other individuals, whether their own or different species. This foraging technique is also practiced by other seabirds such as skuas, and even bald eagles, but we tend not to notice the others since they do not ply their trade so close to us.
(The surprisingly relatable reason why some birds get cranky.)
When birds take food from other birds, they fly after their target, diving at it until it eventually, at least some of the time, drops its prey, whereupon the gull or skua captures it and flies away. This behavior takes a markedly different set of skills than taking a sandwich from an unwary beachgoer, and Kelley and other scientists have examined the details of how and when gulls get food from people, and what might get them to stop.
They first asked whether gulls responded to humans when they tried to grab food. The researchers sat down on the shore and set a plastic bag of potato chips about a yard and a half away; the bag was weighted down so that a gull couldn’t actually snatch the chips and run, but the scientists could see how the birds reacted. Once a gull approached, the scientists did one of two things: either stare directly at the bird as it advanced on the snack, or studiously gaze in a different direction until the telltale rustle of the bag indicated that the gull was about to take the chips.
Of the 74 gulls that unwittingly participated in the experiment, only 27, or a little over a third, approached the food, and just 19 went all the way, so to speak, and attempted to grab it. And the gulls paid attention to whether they were being watched or not, with more of them going for the chips when the researcher was looking away than when they were staring.
The researchers point out that the small proportion of gulls trying to take the chips suggests that the birds are more fearful of humans than people often believe, and furthermore, that sensitivity to behaviors like gaze direction might indicate a rather sophisticated cognitive ability on the part of the gulls. My own take is that the variation among individuals is the most intriguing part of the study. What makes some gulls and not others take up a life of crime?
Another study made that variation even clearer. University of Sussex biologist Paul Graham and students Franziska Feist and Kiera Smith had already seen gulls timing their feeding so that they showed up when schoolchildren were about to discard food scraps. They wondered if the birds were capable of distinguishing whether objects in their environment had been handled by a person, which presumably would indicate their desirability.
The scientists used potato chips again, in their original packages of either blue or green. The person running the test set both colors of chip bags on the beach and held another pack in his or her hand. Of the gulls that pecked at one of the packets, virtually all tried the same color bag that was held by the experimenter. Gulls, then, are remarkably astute observers, which means that trying to discourage them from taking our lunches may involve making sure they don’t see us eating anything ourselves.
(How our actions are making raccoons smarter.)
Again, though, only about a fifth of the gulls that were tested grabbed a bag of chips. It wasn’t because they hadn’t been paying attention either. Some of the gulls who didn’t grab chips went to the spot where the experimenter had been sitting after the trial ended and the person had moved away, which suggests they remembered what had taken place. Perhaps some individuals specialize in snaring human food, while others pursue a more conventional diet of fish or mollusks.
Dogs and horses also pay attention to human cues about where food is or what is edible, but we often think their sensitivity to our reactions reflects an evolutionary history of domestication. It’s obviously beneficial for our pets or work animals to notice what we do, but such behavior seems more unexpected in gulls. Gulls didn’t evolve with humans, much less potato chips, so their ability to grasp the difference between what humans prefer to eat and what they don’t suggests that their cognition may be on a par with animals usually thought to be exceptionally clever, like crows.
How to keep a gull from stealing your food
So if staring at gulls can help deter them, are there any other strategies you might employ? Although it may feel cathartic to shout at a gull trying to take your sandwich, Kelley and her colleagues wondered if shouting is more effective than simply speaking sternly to the bird.
To determine the answer, they placed some French fries in a transparent box and started looking for gulls. When they located one, they put the box down and waited for the bird to notice. They then played one of three recordings: a robin singing, a man saying, “No! Stay away! That’s my food, that’s my pasty!” in a shouting voice, or the same man saying the words in a neutral speaking voice. (Can you tell the experiment was done in Cornwall?)
The birdsong got little attention, but gulls reacted to the human voices by flinching and stopping their advances on the snack. They were also more likely to fly away from the shouts than the speaking voice, suggesting a rather sophisticated discrimination ability.
Like all the best research, the work on gulls suggests many new questions. Like me, Kelley is particularly interested in why most gulls are perfectly happy to leave you and your picnic alone, wondering if older or more experienced birds behave differently. She would also like to know if the birds can recognize individual people, which she started investigating before the pandemic but never took up again.
(How to set up a bird feeder to attract your favorite species.)
What’s more, Kelley has seen changes in the gulls’ behavior; in the nearby town of St. Ives, gulls routinely dive-bombed people for food when she arrived 10 years ago, but in Exeter, they didn’t. Now they do. What’s happened? No one knows. She and her colleagues found that successful dive-bombers come from behind, and are usually adult birds, suggesting they learn over time. To prevent getting your food raided, Laura suggests sitting with your back to a wall or other structure, and maybe under an umbrella.
As with many animals we take for granted or dismiss as pests, there is far more to gulls than meets the eye. Kelley didn’t start out with a fondness for gulls, but now, she says, “I find them charming.”
To me, gulls are avian Boy Scouts—they are loyal, friendly, cheerful, brave, and clean, and while they don’t seem particularly reverent or obedient, that’s a lot to ask of a young boy, let alone a bird.
