Sniffing Out Love: Birds Choose Mates with Sense of Smell

Birds may actually choose their mates not through sight, but through odor. Researchers compared the preen gland chemicals of black-legged kittiwakes with genes that play a role in immunity. Since kittiwakes that are related smell similarly to each other but prefer to mate with genetically unrelated birds, researchers believe that smell may play a role in mate choice.

Reproducing with close relatives may have profoundly negative effects on offspring. However, reproducing with a genetically different individual can result in healthier offspring that are more likely to survive in the wild. It's therefore not surprising that biologists have discovered that in some species, breeding individuals have evolved ways to detect their genetic similarity with those of prospective partners. Female mice, for example, choose unrelated mates by comparing the smell of the urine of each male with their own odors. Now, it seems as if birds may also use smell.

When birds groom themselves with their bills, they spread chemical compounds from their preen glands throughout their plumage. These chemicals produce odors that appear to be unique to each individual, providing an olfactory fingerprint. The scientists collected both DNA samples and preen gland odor samples from nesting kittiwakes. In the end, they found that  kittiwakes avoided mates that smelled similarly to them.

The findings reveal a bit more about how birds manage to choose a mate. More specifically, it shows that smell plays a major role in not just mammals, but also in birds. That said, the scientists plan to continue to examine mate choice in birds and see whether it relates to disease- resistance, as well.

The findings are published in the journal Scientific Reports.