New research suggests the answer could be as simple as eye contact.
Scientists at the University of Exeter in England wanted to know if the birds would be slower to snatch food if they knew a human was watching them. So, they put a bag of chips on the ground and waited.
They discovered, on average, it took seagulls 21 seconds longer to swoop in if a person was staring them down.
Another observation? Only 27 of the 74 birds they watched even came near the food.
In turn, they say a small, and aggressive, minority of the seagull population might be giving the rest a bad name.