When it comes to dating – and mating – it’s tough out there in the animal kingdom. There’s no dating apps, no speed date nights, and you’re hardly likely to get introduced to someone through a friend. Sometimes you have to go that extra mile to stand out, and male crested auklets have come up with a rather unique trait to do this.
A new study in Behavioral Ecology has revealed that it’s not just the bird with the largest crest that gets the girl, but the one with the strongest scent. Combined, the auklets seem to prove irresistible.
Up until a few years ago, no one was really sure if birds had a sense of smell and if they did, what they used it for. The crested auklets of Alaska’s Shumagin Islands, however, are proving that not only do they have olfactory function, but the males use it to attract a mate.
Researchers knew that, like many species, the males with the largest crests gained the most favor with the female auklets. But – unlike other species that show off extreme plumage or sexy-sounding mating calls – the fancy crest of an auklet, though it may look dashing, doesn’t cost a lot of energy to produce, so is perhaps not the best indicator of fitness as a father.
These birds, however, give off a strong, even pungent, citrus odor, which researchers at the University of Alaska suspected was linked to their sexual success.
“The citrus odor is incredibly intense,” Hector Douglas, marine biologist and one of the authors of the new study, told National Geographic. “They’re the strongest smelling birds I know of.”
To test this theory, Douglas and colleagues captured dozens of the birds and put them one by one into a chamber to try and quantify the strength of their scent.
The odor, which is secreted through the neck feathers of the males, produces a compound called aldehyde, which is found in citrus fruit rinds, and often used in perfume. Then the researchers measured the birds’ fitness through a stress test – determining the speed with which the birds activated a hormone called corticosterone. The faster the response, the fitter the bird.
Analyzing their results, the researchers realized the birds with the largest crests also produced a higher quantity of the citrus scent, and the birds with the strongest scent produced the hormone corticosterone faster, indicating that the aroma actually works as an indicator of the birds’ physical suitability as a mate.
“Making a perfume is an extravagance,” Douglas said. “The individuals that are secreting the odor are saying ‘I can do this, despite the fact that I’m giving up some of my metabolic energy.’”
This, the researchers say, shows that birds – or some birds at least – don’t just rely on sight and sound to gauge the suitability of a partner, but smell too.
Why citrus, though, is still unknown.