If there's one thing seagulls are famous for, it's their pro-grade pilfering. They steal your snacks, nick your nosh, purloin your pudding, and liberate your lunch. No morsel is safe in the range of a seagull's beady, greedy eye.
But, as scientists in the UK have discovered, there's a way you can hold them off: keep your own eyes on them.
Yep. Just stare them down. Keep that feathered miscreant in your sights. Make it reeeaaal weird.
It's not just good for keeping your food; in doing so, you might just be able to help save endangered species by reducing conflict between humans and gulls.
"Interactions between humans and wildlife often have detrimental impacts on a wide variety of taxa, and human-wildlife conflict is a major cause of species declines and limited success of conservation efforts," wrote the researchers in their paper.
"Intervention tends to focus on reducing negative effects on humans through managing wildlife populations. However, wildlife management is often ineffective [..] It is increasingly being recognised that, rather than solely imposing controls on wildlife, changes in human behaviour could alleviate these conflicts while also benefiting conservation efforts."
So, a team of researchers led by Madeleine Goumas of the University of Exeter set out to discover if gull thievery could be affected by the behaviour of the humans they were trying to steal from.
They conducted their research on European herring gulls (Larus argentatus), one of Britain's most famous kleptoparasite gulls.
Although populations of these birds are rising in seaside towns, their overall numbers have declined dramatically in recent decades - between 1969 and 2015, the British population of European herring gulls declined by 60 percent as a direct result of anthropogenic influences.
To investigate human-gull conflict, the researchers sought out European herring gulls in coastal towns around Cornwall in the UK, and enticed the birds with fries.
The alluring potato snacks were placed in sealed transparent freezer bags so the gull could be aware of and tempted by the food, but couldn't actually take any. This was to prevent an early reward influencing later behaviour.
The bag was placed on the ground, near one of the researchers. A stopwatch was used to time the gull's approach when the researcher was looking at the gull, or looking away.
When the researcher was looking away, all 19 of the gulls who completed the trial touched the bag of fries. But when the researcher was looking at the gull, they either took longer to touch the bag - 21 seconds longer, on average - or did not touch it at all.
"This demonstrates that gulls use behavioural cues from humans when making foraging decisions in urban environments, and that they find human gaze aversive," the researchers wrote.
"If human gaze aversion is a learned response, those individuals that have been chased away from food by humans may learn to associate human eye contact with potential danger. Alternatively, gaze aversion may be present upon hatching, with gulls being able to generalise the salient features of a vertebrate eye."
Even though it's unclear why the gulls don't like being watched, the research shows that conflict between humans and gulls could be avoided by just a small behavioural change on our end. Just keep the thieving birds under tight surveillance.
This approach could end up being good for the gulls, too. Their natural diet is fish, eggs stolen from other birds, and invertebrates such as crabs and sea urchins. It's unknown how eating oil-soaked fried food impacts their health - that's the focus of the team's next step in the research.
Meanwhile, they urge people to remain watchful.
"Especially now, during the summer holidays and beach barbecues, we are seeing more gulls looking for an easy meal. We therefore advise people to look around themselves and watch out for gulls approaching, as they often appear to take food from behind, catching people by surprise," said behavioural ecologist Neeltje Boogert of the University of Exeter.
"It seems that just watching the gulls will reduce the chance of them snatching your food."
The research is set to appear in Biology Letters.