The Royal Mail has halted deliveries on one Cornish street because of gull attacks on postmen. But with the birds thriving in urban areas, we can only expect more such stories involving these heavily armed birds

It's no joke, being attacked by a seagull. Pensioners have been hospitalised, blood gushing from cut heads. Others have been knocked to the ground, breaking bones. Small dogs have bled to death, children's lips been sliced open, and an elderly man died of a heart attack following a particularly vicious assault in his back garden (3). News that the Royal Mail has temporarily halted deliveries to an otherwise peaceful Cornish cul-de-sac because of the danger should come as no big surprise; it's happened before.

A diving herring gull is a missile: special attack talon on the heel, razor-sharp two-inch beak, 1.4-metre wingspan, more than a kilo of angry bird travelling at 65kph. No wonder there's blood. And there are more and more of them, at least in built-up areas: Britain's urban gull population – thriving on takeaway scraps, open-topped litter bins and landfill sites to scavenge from, and wide ledges and flat rooftops to nest on – is growing by 20% a year. Seagulls can live for up to 40 years, and their survival rate in cities is 95%.

They have, consequently, become less afraid of us. Often, we positively encourage them: leaving leftovers on tables, even feeding them (despite an abundance of notices, particularly in seaside towns, imploring us not to).The problem has become so acute that some towns have turned to deterrents such as hawks, netting, egg-oiling, high-frequency sound systems, rooftop spikes, electrified wires and even ersatz eggs (5). Killing or harming most seagulls is illegal without a permit: while urban populations are increasing, gull numbers overall are in decline.

Swooping gulls can be annoying at the best of times, but at this time of year they can be positively dangerous. From mid-May to late July, when fledglings have hatched but are not yet able to fly, adult gulls become highly territorial and protective of their young. If you get too close, they will use a variety of tactics to try to drive you away.

First comes the "gag call" – a low, repeated warning call that essentially means: Go away. Next is the low pass, within a metre or two of the intruder's head. Then aerial operations commence. Phase one is bombardment: gulls target the perceived threat with droppings and vomit. Phase two is all-out attack – usually a low, raking strike to the back of the head with talons extended.

Once things get to this stage, obviously, there's not a lot you can do beyond duck and try shield your head. Best advice? Keep your eyes and ears open, and learn what the gulls are trying to tell you. Our ignorance of their warnings is their greatest weapon.