Huddled on their low grass nests and braced against gale-force winds, six plump, downy albatross chicks sit waiting for the day they will fly.

Soaring above, a parent bird rides the swift air currents on curved black wings, more than 10 feet from tip to tip, before landing awkwardly to feed its chick.The chance to see the biggest and most majestic of all seabirds draws tens of thousands of people each year to Taiaroa Head, near Dunedin, New Zealand - the only place in the world where the albatross makes its home close to man.

But the pressures of tourism are starting to worry scientists and threatening to add to the list of natural and manmade hazards already facing the bird.

"Foolishly or otherwise, in human terms, it's chosen to breed very close to man, and that is making its life very difficult," said Department of Conservation scientist Chris Robertson.

Every chick hatched here in the past five years has required some form of human care - from hatching in an incubator to injections of antibiotics or even, in one case, artificial waterproofing.

The work of the small team of conservation rangers is an uphill struggle.

An unidentified predator, possibly a stoat, killed four of the 10 chicks that hatched this year, dealing a setback to hopes the 90-member colony can grow large enough to sustain itself.

The deadliest predator - more dangerous than stoats, ferrets or domestic cats - is almost invisible.

A type of blowfly, previously unknown here, arrived in the Otago peninsula outside Dunedin in the late 1980s and began attacking the albatross eggs.

"It lays its eggs and turns itself into a maggot in about half an hour. They literally eat the chick alive, either while it's hatching or in the one to two days after it's hatched," said Robertson.

To ward off the parasite, staff members at the colony painstakingly examine the newly hatched chicks with a magnifying glass and tweezers, searching for maggots just a millimeter long.

But of growing concern is the pressure of the 130,000 tourists a year who come to the Taiaroa Head visitors center, 40,000 of whom pay to view the birds from an observatory.

"As the pressure has increased over the years, there is now very good evidence that the birds have been moving away from the presence of large numbers of visitors," Robertson said.