THE MURRES THE MERRIER - Decoys, mirrors and mood music lure gregarious seabirds back to abandoned breeding colonies

National Wildlife, June-July, 2002 by Laura Helmuth

COMMON MURRES are extroverted birds. They summer in the midst of crowded, cacophonous parties-breeding colonies that draw hundreds to hundreds of thousands of these formally attired, black and white seabirds. So imagine one colony's reaction when, like humans emerging from a fallout shelter after war, the birds returned to their breeding rock one spring to find it completely deserted.

That's what happened 16 years ago to survivors of an oil spill, which had dumped 25,000 gallons of crude just outside San Francisco Bay a few months before the murres gathered together to breed. The spill killed more than 10,000 seabirds, including 6,300 common murres-about half of which had formerly nested on Devil's Slide Rock, a tiny island 15 miles south of San Francisco. For the next decade, not a single murre nested on the haunted rock.

Then in 1996, a few roving murres noticed a change in the old neighborhood. Suddenly, more than 300 of their brethren had settled atop the steep, jagged island. The newcomers were a bit stiff, but they seemed comfortable enough-and their very presence enticed some oil spill survivors to give Devil's Slide Rock a second chance.

Those first new colonists, in fact, were wooden decoys, placed there by a troop of rock-climbing biologists hoping to lure murres back to the island to breed. The scientists also set up solar-powered speakers that broadcast the species' kazoolike calls, as well as mirrors to reflect the movements of any live murres that happened to show up. The ruse worked. That year, a few dozen murres flitted around the island, and six pairs actually bred there. "We were surprised there were any at all," confesses Steve Kress, the National Audubon Society ornithologist who pioneered the project's unusual methodology.

The work at Devil's Slide Rock is one of more than a dozen similar "social attraction" projects that Kress and other biologists have undertaken worldwide. Their experiments are designed to lure colonial seabirds to safer places to nest or, as in the case of the murres, to bring them back to breeding areas they have abandoned. So far, ornithologists have used decoys-with or without the extras of recorded song and mirrors-to attract terns, puffins, skimmers, gannets, petrels and other birds to breeding grounds from California and Maine to Hawaii, New Zealand and Japan.

Why work so hard tricking seabirds to nest on islands that they've shunned? Put simply, biologists do not like to put all their eggs in one basket. Birds that breed only in a few, concentrated colonies-as do many seabirds-are vulnerable to contagious diseases, killer storms, oil spills and other natural or man-made disasters. The more breeding colonies there are within a species' range, the better the chance that at least one population will survive the next crisis and live to build its numbers back up. Such insurance is increasingly important today as both seabird numbers and suitable habitat decline worldwide.

Consider the common murre. This species' populations have plummeted in most parts of its range, a vast area that arcs over the top of the Pacific Ocean from central California to Alaska and back down the Asian side to Japan. A symmetric arc of breeding territories in the Atlantic Ocean begins in Maine, stretches up to Canada and over to Europe, from Scandinavia to as far south as Portugal. Throughout this region, oil pollution has been the murre's worst enemy. Oil kills the birds in two ways: by poisoning them or matting their feathers so badly that they die from drowning, hypothermia or exhaustion.

Kress first came up with the idea of social attraction projects in 1977 when he used decoys to lure Atlantic puffins-another commune-bound breeder-to Maine islands the species had abandoned in the 1800s. "Decoys were long used to attract birds for hunting purposes," says Kress. "I decided to use them to lure birds into historic nesting sites instead." Eastern Egg Rock, the seven-acre island where he targeted his early work, now hosts roughly 40 breeding pairs of puffins each summer (almost all of which fledge chicks) as well as about 50 nonbreeding puffins, up from zero birds a century ago.

Kress, who is a consultant to the murre project, says that it is one of the most successful social attraction experiments yet. Now in the sixth year of a ten-year plan, the project brings more murres to the rock each year. During the 2001 breeding season, 113 pairs nested on the island and 85 chicks fledged. "This was a very good year for the murres," confirms wildlife biologist and project director Mike Parker of the San Francisco Bay National Wildlife Refuge Complex. It's too early to declare victory, however. Parker is waiting to see whether chicks hatched on the rock during the past five years will return to lay the next generation of precious eggs.

Parker's work gets underway each November (while murres are out at sea catching fish and saving energy for the breeding season), when he and his colleagues load up motorized rafts with decoys, ropes, speakers, CD players, mirrors and solar panels, then surf crest the waves up to the edge of Devil's Slide Rock. Fully loaded with these makings of a mock murre colony, the biologists use rock-climbing equipment to scale the island's sheer, 70-foot walls. Over the course of one day on the guano- slick rock surface, they secure all the decoys-placing them in dense clusters, which attract the most live murres. The wooden birds are surprisingly realistic, at least to humans. Viewed through a powerful spotting scope, what appears to be a decoy may suddenly flap its wings and shake its head. As for the murres' reactions, they don't fight or try to mate with the decoys, but they do preen them.