A man walked into the middle of the wedding with a catapult. It surprised me to see him being greeted with warm smiles; and it delighted me, shortly afterwards, when it turned out he was there to shoot stones at the miserable birds which were, frankly, scaring me, because that's what birds always do, always have, more than any other beast - but first of all it gave me a turn.

In my bad drinking days I used to have very weird hangover dreams, daymares in the dehydrated half-light of early morning, which almost always involved a catapult, being used by me to inflict pain on someone who had wronged me. A boss, a misremembered teacher, a dentist. Someone who had walked far too slowly in front of me for far too long. When I had been very drunk, and the guilt and worthless misery and resentment of the functioning percentile of the human race concomitantly higher, it would sometimes, actually rather too often, become a crossbow. The dream would become a daydream. There was consciousness involved. I would hatch elaborate plans for urban revenge by mounting the crossbow on a surveyor's theodolite - no one ever pays attention to what those people are doing with their big sticks and shiny jackets - the better to escape attention until the deed was done.

Anyway, that's why the man with the catapult gave me a bit of a shock; just seeing one of the things, after all those dreams. I still, in cities, have the urge to walk more quickly when I see a theodolite in case someone arrests me for old drunken thoughts, or looses a crossbow bolt through my head. It was a proper catapult, too, a real pro job, all black leather sling and cantilevered pewter, balanced with lazy languid threat across the wizened brown ridges of his hands. There to shoot the wheedling intrusive flappy birds at an outdoors wedding which happened to be taking place in the garden of a hotel I had stopped at in Sri Lanka.

Shooting birds, with his serious catapult and many stones. This gave me, for a while, great joy, to think that there was a country which would do this, pay someone full-time to do this. And then I asked the barman to whom I'd been talking, trying with perhaps not signal success to keep from my voice a bubble of frothy bloodied gloat, how often he made contact. Never, it turns out. He is not allowed, sir, to hit them. The birds are sacred.

For a second, this delighted me even more. It really transported me. A job in which you are paid to fail; in which you can only, only succeed if you fail. Heaven, surely? I used to think the best job in the world was one I heard about (although I think a friend made it up to make me weep) which tested eddies on beaches by throwing tennis balls into the sea, all day, all over the world. I realise there are many fathers out there who will now be queuing to order their daughters to marry me - absolutely not a psycho, darling, and strikes me he's got something of a damned fine work ethic, too - but, still, hey, what a job, catapulting crows and being paid to miss.

But, then, I thought a little further, and what I concluded was this. The Birds are Not our Friends. I wish he'd been allowed to hit them. The India House Crow is the sacred one here, and it's a sod. Big and brave and very croaky and it will have your finger off or your eye out if there's a piece of bread nearby, which is why catapult man comes out, with his threat, and they know, and caw, and wheel and flock and vanish. How can they do that, the birds? Flock? They're just weird, horrid, nasty. Brains the size of grape pips, and little greedy eyes, and yet they can flock, and wheel, tell what the others are doing: there is something dinosaur-atavistic in them all, and if they were a bit bigger and had guns they would rule us. I recently re-read Daphne du Maurier's short story The Birds, and it's set in England actually, and far far scarier than the film. They have never helped us humans, and it's not just the fat black crows; all the buggers, the soft fluttery ones, too, and the fear of what to do with the awful babies with their tumblewretch falls - they are all, I think, monsters. The birds are not our friends. I have lifted spiders from baths. Helped mice out. Spoken to rats. But a bird shut panicked in the house gives me pale horrors way beyond the palpitations of a casual theodolite: it's a thought-fear up there with Jimmy Savile coming towards you in novelty underpants. War on evil unnatural birds, I say, and let's start by paying that man some more but not to miss, and watch the rocks fly.

· euan.ferguson@observer.co.uk