They're the scourge of the skies when you're enjoying a bite by the beach but seagulls may have reached their peak in Australia, according to the country's largest citizen science project.
Birdlife Australia data shows reports of silver gulls are decreasing across the country.
In Queensland's south-east the drop has been especially sharp.
"Since the 90s there's been about a 60 per cent decline in the reporting rates of silver gulls in south-east Queensland," says Birdlife's Sean Dooley.
"The reporting rates — that's the number of times people going out birdwatching are recording them — has declined slightly across Australia.
"It's a fascinating figure that means we may have hit 'peak gull'".
The finding flies in the face of what many beachgoers and picnickers experience when besieged by seagulls, but it may not be that the birds have disappeared altogether.
Super-smart seagulls
Wildlife ecologist Grainne Cleary says gulls are highly intelligent birds that have learned quickly how to live alongside humans and benefit from them.
"They're a general predator which means they'll try a huge variety of food — literally if it can fit in their mouth, they'll try to swallow it," Dr Cleary says.
"They also show kleptoparasitism, which means they'll steal food from other individuals and other species."
In England, a 2019 study of herring gulls — a relative of the silver gull — found the birds track the eye movements of humans and know when it's safest to move in for the steal.
"They have this ability to watch another individual eat and learn that the food is not poisonous and then go in and steal it," Dr Cleary says.
Research recently published in the journal Biology Letters proves herring gulls watch humans to know which foods are best to eat.
Scientists set up blue and green chip packets near individual or small groups of gulls on a beach.
A researcher then sat a short distance away eating from only one colour of chip packet and recorded how the gulls responded.
"Out of the 40 per cent of gulls that actually investigated them [the chips], a huge 95 per cent of them picked the same colour packet as the researcher," Dr Cleary says.
"This is something we thought only us humans could do, and maybe the great apes but no, these birds are outshining other primates in this kind of category."
Dr Cleary says while there is little doubt Australian gulls are highly intelligent, more research is needed to know how they compare to their well-studied English cousins.
"[The chip packet] experiment would be a really great one to replicate in Australia," she says.
"It's a great experiment, you get to eat crisps while the seagulls watch you, then you get to share some with the birds."
Seagull city slickers
It's these seagull-smarts that Mr Dooley says may be why recorded numbers of gulls are dropping; not because they are disappearing, but because they are hiding in plain sight, in areas birdwatchers don't necessarily frequent.
He says as humans have populated and urbanised areas, gulls have become savvy and realised they don't need to scavenge and hunt in natural areas they once would have — the wetlands and reserves that are popular with birdwatchers.
"We've built our cities around the coastal plains and estuaries where they would naturally be anyway, so they have adapted to us coming into their territory," he says.
"They've learned from us, and they've learned to exploit the massive amounts of food waste that we have in our cities.
"[The data] might not mean their numbers are declining but it certainly means they're not being seen as widely as they once were, or as regularly."
Mr Dooley says beachside picnickers could find themselves surrounded by seagulls even more frequently as people learn to divert more waste from landfill and keep birds and other scavengers out of bins.
"The way that we use our cities and control our waste management could mean we're providing fewer opportunities for gulls to take a free snack from us," he says.
"That could correlate to them getting more bold around us down at the beach because there's less rubbish around.
"It would be a fascinating research project to look into."
