Let one in and suddenly it's a horrifying scene from an Alfred Hitchcock movie - the invasion of the inland seagulls

Pay attention, class. Today's subject is seagulls.

Suddenly, they're everywhere. Here in London they are as numerous as sparrows and crows, if not more so.

When I was a kid in the 1950s, seagulls were irrevocably linked to summer holidays. Staying in a seaside boarding house, or in our case, a caravan, the early morning shrieks of various seagull species - terns, herring gulls, black-headed gulls - as they circled the wakes of trawlers coming back to harbor meant you were definitely on holiday.

The idea of seagulls in urban inland areas simply didn't register. Not, that is, until I was visiting my parents in rural Oxfordshire on leave from Vietnam in the early 1970s. I looked out the window to see our neighbor plowing his fields only to be startled by the sight of a flock of seagulls circling the broken earth thrown up by the plow. And my parents lived 100 kilometers or more from the sea.

According to bird experts, including those at the august and learned Royal Society for the Protection of Birds, changes in fishing habits, unusually bad weather at sea, and the sudden abundance of discarded take-away food in trash cans in Britain's cities, gave our snowy-colored friends a whole new diet.

Being intelligent animals, they started to migrate inland. Indeed, these days it's unlikely many of the so-called urban gulls have even seen the sea.

Oddly enough, they all seemed at first to be mute, and it's only in the past few months that I've noticed the flocks of gulls that seem to haunt my neighborhood in Greenwich have started their characteristic shrieking and calling.

In the Chinese city of Kunming, Yunnan province, which is known as the Spring City because of its mild climate, I understand there's even a Kunming Seagull Festival in January. It started back in 2008.

Tens of thousands of black-headed gulls have flocked to Kunming's lake from Siberia every winter for the past 28 years. In March they head back to Siberia, though not before being the focus of the Seagull Festival, arranged by local conservationists who want to promote awareness of environmental and animal protection issues.

Events include a shopping street, sports activities and a special Seagull Dance by a local troupe.

Which brings me in a roundabout way to two new China Daily fans here in London.

Malcolm and Ernest came to our attention a few weeks back. A new colleague, who didn't realize we must NEVER open the windows (we're on the fifth floor), put some food out on the ledge.

Malcolm arrived as quick as a flash, and gobbled it all up.

The next day he arrived with his best friend, Ernest, and they both stood on the ledge for a considerable time, waiting - in vain as it turned out - for a second helping.

They have continued to do so for weeks at the same time every day, to the consternation of bird lovers in the office who have to be restrained from opening the windows. Sadly, with gulls, let one in and suddenly it's a bit like a scene from Alfred Hitchcock's dark thriller The Birds.

Sorry guys. One day we'll explain health and safety rules to you.

The author is managing editor of China Daily European Bureau.

Contact the writer at chris@mail.chinadailyuk.com