June 2, 2023

Laysan albatross have only two main nesting sites

Laysan albatross have only two main nesting sites
Laysan albatross have only two main nesting sitesLaysan albatross have only two main nesting sites

ON THE FACE of things, the Laysan albatross is doing fairly well. Its population is estimated at around 1.6m, and may be growing. The International Union for Conservation of Nature (IUCN) classifies it as “near-threatened”, putting it on the second rung from the bottom of the organisation’s seven-rung ladder to extinction. A cause for moderate concern. But not, you may think, something that should be top of conservationists’ lists of priorities. However, like another reasonably abundant migratory species, the monarch butterfly, the Laysan albatross has an Achilles heel.

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Though monarchs range across much of North America, many are, or are the descendants of, insects that have roosted over winter in the same few groves of trees in central Mexico. Destroy those trees and you would imperil the species. The Laysan albatross has a similar vulnerability. Adult birds traverse much of the Pacific Ocean. But more than 90% of them started life on one of two specks of land, Midway and the eponymous Laysan, which are among the most north-westerly members of the Hawaiian archipelago. Wipe out those breeding colonies and the Laysan albatross would shoot right up the IUCN ladder.

And that is just what some ornithologists fear, for both Midway and Laysan, which are among the oldest parts of the Hawaiian chain, have been eroded over time from their original splendour as mountainous volcanic islands to their current state as coral atolls protruding a few metres above sea level. A storm surge in 2011 destroyed hundreds of thousands of nests, and even in normal years thousands are thus lost. Rising sea levels may make this worse. Time, then, to spread the species’ risk by establishing Laysan-albatross colonies elsewhere.

A project to do so began in 2015 when America’s navy, its Fish and Wildlife Service (a government agency) and several private conservation organisations led by a group called Pacific Rim Conservation began collaborating to move albatross eggs from another member of the archipelago, Kauai, which supports a small colony of the birds, to Oahu, home of Hawaii’s capital, Honolulu. Here, after incubation and hatching, they are transferred to a wildlife refuge ten metres above sea level, and hand-fed squid and fish for five months until they fledge and leave the island.

While there, they are exposed to fibreglass decoys and solar-powered megaphones that broadcast albatross calls. The hope is that these tricks will encourage the chicks to imprint on the area and come there to breed as adults. Since young Laysans spend three to five years at sea before returning to their birthplace for the first time, it has taken a while to discover whether that works. But the auspices seem reasonably good. Of the 46 Laysans successfully raised and fledged from the 2015, 2016 and 2017 breeding seasons, seven have so far returned. And, as a bonus, the decoy birds and calls have also attracted hundreds of adult Laysan albatross visitors, including four pairs that have begun to nest.

There are caveats. The transfer of eggs from Kauai was a proof of principle rather than a true conservation effort. Kauai is not an atoll, and the nests in question were chosen because they were too close for comfort to a navy airfield there. More seriously, there is the question of protecting the albatrosses if they do establish themselves on Oahu. The probable reason why so many of the birds now nest on Midway and Laysan rather than on larger islands is lack of predators. Small rodents, introduced by human visitors, were a problem on both places (though they have been eliminated from Laysan). Oahu, though, is rife not only with these, but also with larger imported predators. The albatross sanctuary is therefore surrounded by a fence two metres high that keeps out cats, dogs and pigs, and which is also dug into the ground to stop rodents burrowing under it. The 6.5 hectares of land thus fortified could accommodate several tens of thousands of pairs of nesting birds. As Jared Underwood of the Fish and Wildlife Service puts it, “We’re just allowing them to come back.” But that permission depends on the fortifications being maintained.

Nothing daunted, though, the project’s partners are now expanding. They have taken to accommodating black-footed albatross, a related species with similar habits, on Oahu as well. These have been translocated from both Midway and another atoll, Tern Island. And the partners are also trying to establish colonies far away from the Hawaiian Islands, on the Channel Islands off the coast of California and on Guadalupe, off the coast of Mexico. If things go well, then, the Laysan-albatross conservation project may prove a rare example of shutting the stable door before the horse has bolted.

This article appeared in the Science & technology section of the print edition under the headline “Don’t put all your eggs in one basket”