Seagull numbers swell in line with growth of modern 'throwaway society'
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They seem to be everywhere — the coast, inland, our sporting venues and shopping strips — but why are there so many seagulls? And did you know they are a protected species?
Researchers say Australian seagulls could be the unwitting beneficiaries of an increasingly "throwaway society" ready to pounce on discarded food at the risk of their own health.
The often misunderstood native bird — officially called the silver gull — is increasingly populating areas away from the coast, even in industrial areas, as well as traditional hunting grounds like the beach and picnic grounds.
Editor of Australian Birdlife Magazine Sean Dooley said seagulls were an often misunderstood bird, yet one with an interesting societal pecking order.
"They are essentially scavengers, so they will go were the food is which is a large factor in the growth of populations," Mr Dooley said.
"They were not that common a sight 50 years ago. Indeed they were fairly thinly scattered around the coast, but since we've had human settlement with our wasteful and throwaway society, they've really bred up in numbers because we've provided a whole lot of food for them."
Structures and hierarchy
Mr Dooley said the social structure within seagull flocks followed strict lines.
"They are a highly social bird with really strong social structures and hierarchy," Mr Dooley said.
"You'll see the gulls with bright red bills — which indicates age — and they're usually the ones hunching and towering over the others making all the noise while the others will look rather sheepish and submissive."
Mr Dooley said male seagulls, like many other species of bird, do not have a penis. Instead both sexes have a multi-tasking orifice called a cloaca.
The female typically lay broods of one to three eggs a year, but could produce that number twice a year if conditions permit.
"They are quite opportunistic when it comes to mating," Mr Dooley said.
"And it's not uncommon for them to make use of mating grounds set up by other species of birds either. Basically if conditions are good and there is plenty of tucker around, they're good to go at any time of the year."
Coupled with an increasingly available source of food, Mr Dooley said while there was no definitive data to prove so, seagull numbers were "more than likely" on a sharp rise.
"We are seeing more and more of them in places we wouldn't have not so long ago," Mr Dooley said.
Seagulls are a protected species
"It's now a matter of how best to manage those numbers in a humane way."
As a result, new methods of deterring gulls are being sought. However, as the seagull is a protected species options thus far appear to be limited.
Victorian falconer Graeme Coles said other larger birds of prey, including wedge-tailed eagles, brown goshawks and peregrine falcons had been successful at venues such as the Melbourne Cricket Ground, Flemington Racecourse and Rod Laver Arena-venue for the Australian Open tennis tournament.
Mr Coles said due to safety reasons, the eagles were not able to be released and were instead tethered to the roof of the MCG which he said was still enough of a deterrent for the seagull.
"It's what we call a prey, predator response," Mr Coles said of the hierarchical relationship between the birds.
"It's not much different to humans going to the beach.
"If we know there's a shark swimming in the water you'd be pretty brave to jump in. All preyed birds, such as the seagull have that in built fear response so when we introduce a predator into that environment, it really puts the willy up them."
Mr Coles said he'd noted increased numbers of seagulls in industrial areas with abundant sheltered areas for large populations of seagulls.
They don't find much of their own prey
It's increasing in certain areas due to the availability of discarded food," Mr Coles said.
"They call into these large scale sporting venues for the free feed, so a residential bin, picnic ground of factory is not really any different."
Similarly, Mr Dooley said seagulls were as opportunistic when it came to their diet.
"Their primary source of food is found in clumps of seaweed or while foraging along the seashore as they don't tend to find much of their own prey," Mr Dooley said.
"But of course, it's a rare day when a seagull turns its nose up to a hot chip which of course is not naturally a part of its diet. They are quite clever and adaptable. While the chip is not really that great in nutritional value, there's a lot of energy in it so they'll happily take it."