JEAN-CLAUDE STAHL has a determined look on his face as he edges towards the albatross. It stands three metres away, patting the ground nervously with its saucer-sized feet. In between is a tangle of tree-daisy branches, each studded with brittle, broken twigs. Negotiating a thicket of this stuff without getting snagged or stabbed is difficult at the best of times, and downright impossible if you’re lunging after an albatross.

Stahl wants this bird. He has been on North East Island for two days and has seen only a handful of albatrosses. They are late this year. It is mid-December, and each new day should see dozens, if not hundreds, of albatrosses returning to the Snares, a cluster of islands and islets a little over 100 km south-west of Stewart Island. Instead, the pedestals on which they lay their eggs and brood their young stand empty: peat chimney pots scattered among the rocks, tree daisies and tussocks.

Stahl, a seabird scientist with the Museum of New Zealand/Te Papa Tongarewa, in Wellington, is contributing to a long-term study of the foraging behaviour and population dynamics of the southern Buller’s albatross, one of 13 species of albatross which breed in the New Zealand region. As often as four times a year, he and his Christchurch-based colleague, Paul Sagar, of the National Institute of Water and Atmospheric Research (NIWA), spend up to a month on the Snares and Solander Island—the only two places this species breeds—gathering data and generally learning all they can about the birds.

Their research comes at a crucial time for all albatrosses. Seventeen of the world’s 24 albatross species are regarded as globally threatened. In 2001, the conservation group BirdLife International launched a Save The Albatross campaign, enlisting the patronage of the Prince of Wales, to raise awareness of the birds’ plight. A key issue is commercial fishing—longlining in particular—which is believed to be responsible for the death of 300,000 seabirds a year, several thousand of them albatrosses.

It is an ignominious death for a majestic bird. Diving on baits as they are lowered into the water, an albatross is liable to be hooked, dragged under and drowned. Between 1988 and 1992, an estimated 1600 Buller’s albatrosses died in this way in the Japanese bluefin tuna fishery off the southern coast of New Zealand. Still more died in trawling operations for squid and hoki.

As with all long-lived, slow-maturing, slow-breeding birds, the loss of breeding adults from a population severely diminishes its long-term prospects. Such species are doomed to inexorable decline and eventual extinction unless adult birds can be saved from premature death.

But here is a puzzle: despite the longlining deaths, numbers of southern Buller’s albatrosses on the Snares increased by a surprising 78 per cent between 1969 and 1992, and a further 8 per cent from 1992 to 1997, to a present population of around 8900 pairs. On Solander Island, 200 km to the north, the reverse trend has been observed, with the population possibly declining by up to 19 per cent between 1985 and 1996, and now numbering some 2600 pairs.

What is going on here? Why should one population increase and the other decrease, with no observable migration between the two? To answer this question, detailed knowledge of the birds’ foraging habits is required, and the only way to track these ocean wanderers—capable of travelling thousands of kilometres during a single feeding trip—is by satellite.

Stahl has four satellite transmitters, each weighing about 70 g and costing $3500, which he plans to attach to two breeding pairs. The movement of these individuals will then be followed for up to five months, until the transmitter batteries wear out. Stahl has seven days—the duration of this trip—in which to deploy the transmitters and conduct his usual round of data-gathering: weighing (to assess breeding condition), measuring (to determine the sex of new birds) and band checking (to find out which birds are the early arrivers).

He advances towards his quarry. I take up a flanking position, as if herding a sheep. The bird, sensing capture is imminent, ducks under a fallen tree limb and makes a dash for the cliffs. Stahl vaults over one branch, sidesteps several others and seems within inches of grabbing it when it reaches the cliff edge.

Parachutes not being part of an ornithologist’s kit, Stahl gives up the chase. We stand on a rock slab and watch the albatross soar away, the white of its feathers mingling with the whitecaps far below.