Shouting at seagulls makes them more likely to leave your food alone, research suggests.
Researchers at the University of Exeter looked at different ways of deterring the birds from approaching a box of chips on the ground.
Testing a total of 61 herring gulls across nine seaside towns in Cornwall, they played either a recording of a male voice shouting the words "No, stay away, that's my food", the same voice speaking those words, or the 'neutral' birdsong of a robin.
The experiment found nearly half of those gulls exposed to the shouting voice flew away within a minute.
Only 15% of the gulls exposed to the speaking male voice flew away, while the rest walked away from the food, still sensing danger.
In contrast, 70% of gulls exposed to the robin song stayed near the food for the duration of the experiment.
Dr Neeltje Boogert, of the Centre for Ecology and Conservation at Exeter's Penryn Campus in Cornwall, said: "The difference was that the gulls were more likely to fly away at the shouting and more likely to walk away at the speaking.
"So when trying to scare off a gull that's trying to steal your food, talking might stop them in their tracks but shouting is more effective at making them fly away."
The recordings, in which five male volunteers spoke the same phrase in a calm voice and, separately, in a shouting voice, were adjusted to be at the same volume, which suggests gulls can detect differences in the acoustic properties of human voices.
Dr Boogert said: "Normally when someone is shouting, it's scary because it's a loud noise, but in this case all the noises were the same volume, and it was just the way the words were being said that was different.
"So it seems that gulls pay attention to the way we say things, which we don't think has been seen before in any wild species, only in those domesticated species that have been bred around humans for generations, such as dogs, pigs and horses."
The experiment was designed to show that physical violence is not necessary to scare off gulls.
"Most gulls aren't bold enough to steal food from a person, I think they've become quite vilified," added Dr Boogert.
"What we don't want is people injuring them. They are a species of conservation concern, and this experiment shows there are peaceful ways to deter them that don't involve physical contact."
