Posted on: Monday, November 15, 2004

By Jan TenBruggencate
Advertiser Staff Writer

One of the questions that goes through most folks' minds when they see the vast seabird rookeries of the northwestern Hawaiian islands is how partners recognize each other from among the hundreds of thousands of nearly identical nesting pairs.

To a human, every Laysan albatross, for example, looks very much alike. Yet, even after being hundreds of miles out at sea feeding, mates seem to easily find each other on land.

The answer, according to two researchers, may be smell. Gabrielle Nevitt of the University of California at Davis and French researcher Francesco Bonadonna placed mated birds in cotton transport bags, which become permeated with the birds' scents. They then placed birds in mazes to find out whether the mates could distinguish their mates' smells from those of other birds.

They found that more than four out of five times, birds went to their mates' smells rather than sites that smelled like other birds.

"Our work shows that birds can recognize each other by scents," Nevitt said. "The sense of smell is often overlooked in birds, and it is possible that a variety of species use scent in individual recognition. We worked with procellariiforms because these birds are known to have a super well-developed sense of smell."

Procellariiforms, or tube-nosed seabirds, include petrels, albatrosses, shearwaters and prions. The researchers did their work with Antarctic prions, which readily run through mazes.

"We studied prions because they are burrow nesters and we already knew that they used olfaction (smell) in a variety of behaviors," Nevitt said. The birds spend as much as two weeks feeding at sea before returning to the rookeries to take over nesting from their mates. The researchers figured that if they could easily recognize a partner's smell, they could find their nests.

The work opens up new lines of questioning that could be the subject of further research. One thought: Might they also be able to distinguish by smell their close relatives from unrelated birds.

"The discovery suggests a way that seabirds (procellariiforms at least) may be able to tell each other apart prior to breeding. I stress that we didn't test this in this study, but the implication is that birds might be able to use scent to tell something about how closely related they are to each other. This could be important in choosing mates," she said.

If you have a question or concern about the Hawaiian environment, drop a note to Jan TenBruggencate at P.O. Box 524, Lihu'e, HI 96766, e-mail jant@honoluluadvertiser.com or call (808) 245-3074.