Science Spotlight: Marbled Murrelets

by Yasemin Saplakoglu

They sneak silently into their nests an hour before sunrise, after spending a day and a night hunting at sea. Hundreds of feet off the ground, they settle into the highest branches of old-growth trees. On their nests, they barely move. Meet the marbled murrelet, a seabird that turned into an elusive forest dweller somewhere along the evolutionary trail.

Scientists have found fewer than a dozen murrelet nest sites to date, says Keith Bensen, a fish and wildlife biologist at Redwood National and State Parks. The first was in 1974, when a maintenance worker at Big Basin State Park climbed a redwood tree and happened upon a fluffy nestling that, to his surprise, had webbed feet. Indeed, murrelets were the last North American birds to have their nesting habitats found.

“Murrelets are doing everything they can to hide from predators,” says Bensen, leaving scientists trying to piece together their life stories. These seabirds have adapted to their woodsy homes, taking on a reddish-brown and speckled color during breeding season that looks like “sun-dappled light going through a forest,” Bensen says.

The male and female murrelets incubate their egg—usually one per nest—in 24-hour shifts. At sea, they swiftly dive to hunt for herring, smelt, and anchovies, then flit back from the water to soundlessly switch guard duty before dawn.

Marbled murrelets are endangered in Washington, Oregon, and California because of extensive logging in their old-growth habitat. Even in parks where the ancient trees are protected, murrelets and their chicks are heavily predated by aggressive Steller’s Jays. Although tracking murrelets is difficult, ecologists believe about 4,000 remain in California, down from an historic average of 60,000.

Note from the editors: Science Spotlights are a joint project of the UCSC Science Communication Program and Hilltromper. This article was published in May 2017.