Whether it is standing on the end of Clapham Junction station recording train numbers, or watching a football match in every league football ground in Britain, large numbers of people are consumed by this strange kind of collecting.

No doubt some people will disagree, but I would add "twitchers" into this category of people.

While many are drawn to bird-watching by a love of the countryside and observing the wonderful natural sights of our feathered friends in their natural habitats, others take the activity to the level of a sport.

What amazes me about twitchers is how quickly news spreads through their fraternity.

While watching the news this morning, I saw that the latest prize was a view of the rarely seen (in this country) white-crowned sparrow.

The hapless bird had taken a wrong turn somewhere on its usual migratory route in North America and turned-up in Cley Next The Sea in north Norfolk.

The poor sparrow now has to face up to the fact that it will probably lead a lonely existence from here on as far as bird company is concerned, yet have to deal with hordes of people keen to record its every move.

The news footage this morning showed the large numbers of people that had descended on the village, with enormous cameras trained on the bush where the sparrow has been resting after its monster journey across the Atlantic.

The white-crowned sparrow is not a rare bird, but this is only the fourth sighting of it in this country.

Normally a resident of North America, it has a fairly unremarkable existence and probably doesn't feature very highly on a serious American birdwatcher's list of "must see" birds.

However, very occasionally the sparrow makes a rare foray to Europe, probably as a result of being blown off course or hitching a ride from a passing ship.

No-one quite knows how the Norfolk individual got to the UK, but in the heat of trying to capture it on film I don't suppose too many of the twitchers really care. For them, it is the opportunity of a lifetime, while to most scientists and ornithologists it represents just an oddity or fluke.

What can be in no doubt, though, is the effect that this small visitor has had on the rural economy of north Norfolk.

While January is probably a pretty quiet time of year for local businesses, most are now enjoying the boom times.

For the local church, too, a much-needed cash injection to the repairs fund, as many of the twitchers have donated generously to offset the disruption of their presence to the local community.

It's amazing what effect a little harmless fun can have – just imagine if it was a really rare bird that had shown up!