Musk by Prion. Antarctic prions can identify their mates by smell.

That Familiar Nest Odor

Birds are not renowned for their sense of smell. But new research shows that a species of seabird prefers the scent of its mate to those of other individuals in the colony. The odors may help the birds locate their burrows and, perhaps, even choose a partner.

Each year, seabirds called Antarctic prions return to breeding colonies on sub-Antarctic islands with their lifelong mates. The pairs build shallow burrows and then split the duty of incubating the eggs, spending the rest of their time looking for food. Because prions can locate their own burrows among those of hundreds of neighbors in the middle of the night, researchers Francesco Bonadonna, an animal behaviorist at the French national research center CNRS in Montpellier, France, and Gabrielle Nevitt, a sensory ecologist at the University of California, Davis, began to suspect that they were using odor cues.

To test their hypothesis, the pair put birds in a "Y"-shaped maze and placed cotton bags (originally used to transport the musky-scented prions) at the end of each tunnel, providing the birds with a choice of odor. The seabirds preferred the smell of their mates over odors from other prions in the colony. To ensure that the seabirds weren't just choosing the more familiar odor, the researchers then tested whether the prions would pick their own odor over that of another colony member. In that case, the prions avoided their own smell in favor of the other, more novel odor, the researchers report in the 29 October issue of Science.

The results provide strong evidence that the prion's olfactory system is developed enough to identify their mates just based on smell, says Bonadonna, suggesting that they may also be able to sniff their way home.

But behavioral ecologist Jill Mateo of the University of Chicago cautioned against overgeneralizing the findings: "We don't really know that the birds can really discriminate between individual birds. These results don't mean that they could tell Joe versus Bob, for example."

Both Mateo and the study's authors hope that the new findings will prompt other researchers to look more closely at avian olfaction. "We don't know how extensive this ability is," says Nevitt, adding that future studies could examine whether the birds use odors to aid in mate selection, for example.

Related sites
More about Antarctic prions
Gabrielle Nevitt's home page
Science story on bird olfaction, 22 October 1999