To the growing list of places in Vietnam that claims to have discovered eco-tourism, add the name of Dao Co (Stork Island). It will have to take its chances for the claim along with all the others but certainly they won't be lessened by its celebrated Island of Storks.

It nestles in Chi Lang Nam Commune and has been quietly pulling bird-watchers - around 15,000 annually, to an out-of-the way part of Hai Duong Province - since the early 1990. That's a modest figure but local tourist officials are hoping to spread its attractions wider without trampling on the very nature that attracts visitors in the first place. Welcome to eco-tourism - welcome to the problem.

Stork island, one writer enthused "rises like a jewel blessed by nature" in the middle of the 2,832km2 in Chi Lang Nam. Few ornithologists - those birdwatchers - would disagree. It's home mainly to a mere nine varieties of storks, Chinese pond herons, jabirus, buff-backed and grey herons, and the grey, blue and black bitterns, stopping off on their way to China, Myanmar, India and Nepal. But don't forget the common teal, wild ducks, moor hens, the pelicans or the snipes - all faithfully recorded in the Vietnam's nature bible, the Red Book. But it's this time of year that most excites visitors and locals as spring heralds the arrival of tens of thousands of storks. Local experts somehow seem to have deduced that each flock of storks numbers 70, arriving in clusters as night falls to take up residence on their island.