Why drawing eyes on food packaging could stop seagulls stealing your chips

The increasingly urban lifestyles of seagulls in the UK and around Europe has made them experts at grabbing food from unsuspecting outdoor diners. Herring gulls in particular are gaining a reputation for food theft in seaside towns like Falmouth in Cornwall, where I live.

On a day out at the beach last summer, I watched as one rummaged through an unattended bag and hopped off with a packet of crisps. Sadly, the gull didn’t hang around long enough for me to see whether it successfully opened the packaging.

Watching this kind of behaviour led me and my colleague Neeltje Boogert to explore new ways of deterring these resourceful birds. Our new research shows that displaying a pair of eyes on food packaging can be enough to stop some gulls from pinching your food.

This builds on our previous work which showed herring gulls approach food more slowly when someone is looking at them directly, compared with if they are looking away.

Many animals – both wild and domesticated – are very aware of eyes, which can indicate the presence of a predator or be used to communicate intent. Direct eye contact often conveys aggression, while looking away indicates a lack of threat.

Animals generally respond defensively when they see eyes staring at them. This is probably an instinctive tendency, since avoiding being eaten by a predator can be a split-second response.

Some animals may have evolved markings to exploit this behaviour. So-called eyespots are found on many insects, amphibians and fish, and they come in a variety of colour, size and pattern combinations.

Exactly how eyespots might deter predators has been hotly debated by scientists for over a century. They may increase predator wariness by being mistaken for predator eyes, or divert attacks to less important parts of the body.

Given that evolution suggests eyes are a good way of increasing animal wariness, the idea of mimicking nature by using fake eyes to deter other animals has been tried in a variety of settings.

In Botswana, livestock are at risk of being eaten by ambush predators such as lions and leopards, which causes conflict with farmers. To test whether eyespots could reduce the risk of predation, experimenters painted pairs of eyes or crosses on the rumps of cattle, or left them unmarked. This was repeated across multiple cattle herds, and any attacks on cattle were recorded.

During the study, 19 cattle were killed by lions or leopards – but none of the cattle with eyespots on their rumps were among them. They were also attacked less than either cattle with crosses or unmarked cattle, suggesting that eyespots can be an effective deterrent for a wide range of animals.

Put off by the eyes

For our study of herring gulls, we tested this idea in coastal towns in Cornwall where gulls are known to take food from people eating outside. We stuck pairs of eyes onto food takeaway boxes and presented individual gulls with a choice of two boxes placed two metres apart on the ground: one box with eyes and one plain box.

Gulls appeared to be put off by the eyes, as they were slower to approach and less likely to peck at these boxes, compared with the ones without eyes.

We also wanted to know whether gulls would, over time, figure out that the eyes on boxes were not really threatening. To test this, we presented 30 gulls with one takeaway box either with or without eyes, but did this three times for each gull over a short amount of time.

Around half the birds never pecked at the box with eyes, whereas the other half quickly approached and pecked. This suggests there could be a sustained effect from the fake eyes for some gulls that do not realise they are being tricked.

We now want to test this in a more realistic setting, by teaming up with food vendors and asking them to use takeaway boxes with eyes on. While this might only ever deter half of gulls from stealing food, perhaps when paired with other deterrents – including shouting – it can have an impact on the amount of food theft.

Eye-like markings have already been used to exclude birds from certain areas, including keeping starlings away from crops, seabirds from fishing nets and raptors from airports.

Humans respond to eyes too

It’s interesting to note that people, like gulls and many other animals, also pay attention to eyes. Images of human eyes have been found to reduce bicycle theft, reinforce honesty, and even increase charitable donations – all by creating the impression of being watched. This is probably because we are a social species, and tend to act more honestly if we feel we might be judged by an onlooker.

But as with herring gulls, the effect on human behaviour is inconsistent. Images of eyes can nudge behaviour in certain situations, but they don’t work on everyone.

Whether protecting chips, bicycles or cattle, the next step is to understand why some animals (and people) do not find eyes aversive. But already, the evidence is clear that fake eyes can offer a cheap, simple way to mitigate conflict with humans and other animals.

Laura Kelley receives funding from the Royal Society.