Not often is one physically assaulted by a bird. Farmyard cockerels do sometimes spar up at humans, it is true, but for a wild bird to launch an attack is rare indeed. Yet earlier this year I found myself locked in single combat with a rogue capercaillie.
We were driving through a pine forest when my guide let fall that we had just entered the territory of a male caper, which, crazed by sex, was driving all comers off his beat. The moment we stopped, out he strutted, down a bank, and wham! - beak-first into the front of the Land Rover. A colossal grouse, more than 2ft tall, he was nearly black in the body, with hints of brown, bottle green and white, but scarred and bloodied about the head from fighting. With his bony beak pointed straight upwards, he was uttering extraordinary, metallic, clicking noises.
When I got out and tried to chat him up, he came straight for me, pecking at my legs, and when I put the toe of one boot on his breast, to push him away, he let fly an incredibly swift double clap with his wings - babbom! - striking furiously on either side of my right knee.
So consumed with aggression was he that no amount of shooing could drive him off. I felt sure that if I had seized him by the neck and whirled him round, he would have come back into the attack the instant he regained his feet. In the end we reboarded our Land Rover, nudged him out of the way and drove off.
I mention the incident now because today and tomorrow World Birdwatch 1997 - the biggest twitchers' turn-out in history - is taking place. The event had its origins in Birdwatch UK, during the Eighties; the idea spread to Europe, and then in 1993 went global. This year more than 90 countries are taking part, including China, Bolivia and Yemen, and it is hoped that in Britain alone at least 50,000 fans will be out there seeing what they can spot.
The whole jamboree is co-ordinated by Birdlife International, of which the Royal Society for the Protection of Birds is the UK partner, and the aim of this "global celebration", besides giving innocent pleasure, is to raise awareness of the need for conservation work.
For me, the idea of joining an organised group to watch birds is somehow unsatisfactory. I would rather go out on my own and see what I can find. Nevertheless, I recognise that many twitchers become so fanatical that they do not mind if they are part of an army, provided they can set eye or lens on their quarry.
According to Chris Harbard, an expert at the RSPB, many addicts develop an interest in birds as children, and carry the hobby on into adulthood. "First they see a challenge in identifying as many species as possible, by looks or voice. They keep lists, and get into friendly rivalry with others about the number they've seen in a year." Anyone who claims a bird which he has not seen, and is found to be fabricating evidence, becomes known as a "stringer" - the ultimate term of abuse.
All dedicated twitchers, it seems, set themselves targets: 300 species a year for the really serious, 350 for those on the verge of fanaticism. As a warning to all, Mr Harbard cites the example of Lee Evans, the Great Twitcher of Luton, who deserted his wife on the first night of their honeymoon to set off in pursuit of a rare shrike, and wrecked his marriage by driving 80,000 miles a year, at a cost of pounds 10,000, in furtherance of his obsession.
I myself have always been wary of shrikes ever since, as a 12-year-old, I told a friend of the gamekeeper that I had heard a peculiar cry in the valley below our house. "Ah," said Jack when I described it. "That was a lesser shrike, boy. Rare old bird that. Takes a bit of seeing.
You want to get down there arter 'ee." For months I searched in vain for the elusive caller and, only by chance, after much further ribbing about my lack of success, did I discover that the creature making the noise was a donkey.
Perhaps it was having my leg pulled so comprehensively that confirmed my bent as a solitary bird-watcher. Over this weekend I shall certainly be on the lookout, but alone.
The other day, in the Highlands, I had the luck to see a golden eagle soar away off rocks below me and out over the glen. Through binoculars I could tell that for a mile or more her wings never moved, but she changed course slightly by dipping the side-feathers of her tail, first one way, then the other - a majestic display of gliding that I shall never forget.
That, and the mad caper, have given me bird memories to last into my dotage.
For information on the nearest event of World Birdwatch, call the RSPB hotline 01273 299399