We all like to think our choice of hairstyle helps tilt the scale in our favour when looking for a date. We even see it at work in the bird world. It was during a conversation about this very topic back in the 80s between Ian Jones and his PhD supervisor that the topic turned to the flamboyant hairstyles found on the Alaskan auklet.
Are those tall feathers that naturally jut out from the heads of auklets good for anything other than a sexual ploy?
Dr. Jones, now a professor at Memorial in the Department of Biology, and his graduate student, Sampath Seneviratne, found an answer. They spent months with the auklets, conducting sensory experiments in a created habitat where they taped the feathers down to see what would happen. As the auklets bumped their heads off the faux-cave ceiling it became clear — like a cat’s whiskers, the feathers act as a sensory device. These researchers believe this could revolutionize how we view ornate feathers on birds.
“I was skeptical at first knowing that anyone who had tested the use of these feathers had tested them as nothing more than sexy ornaments but I went in with an open mind. Only when we counted how many times the bird bumped his head did we realize that this weird and wacky phenomenon was real,” says Dr. Jones.
This nocturnal family of birds is made up of five species which display a varying amount of facial ornamentation including bizarre facial plumes derived from contour feathers and filoplumes. They nest in tiny rock crevices on the volcanic Aleutian and Kuril Islands on the edge of the North Pacific.
To determine whether or not there was a correlation, the researchers caught large number of birds in their Alaskan breeding colonies and carefully taped the forehead crest and superorbital plumes down. The birds were then exposed to a test chamber – a light-proof maze that simulated their natural breeding crevices. Their resulting exploratory behaviour was recorded on an infrared digital camcorder. Each bird was tested three times in the chamber, in random order: once with the feathers taped down, once with the feathers free and once with the feathers free, but with tape attached to the bird’s head in the same position as in the first test. The latter “sham” test was used to determine if the tape alone would prove to be enough of a distraction to affect the behaviour of the birds.
The prediction was that if the whiskered auklets, the most decorated of the auklet family, used the feather ornaments as a sensory device to avoid obstacles, they would bump their heads against the barriers of the chamber more frequently once the feathers were temporarily “eliminated.”
“We found there was 275 per cent increase in head bumps when the crest was cancelled out and this showed that they primarily use this crest as an immediate clutter detection device, much like a blind man uses a cane,” said Mr. Seneviratne. “In addition, the longer crested birds had more difficulty navigating in the chamber in the absence of the crest than the shorter crested birds.”
They believe this is the first empirical evidence for a possibly widespread but overlooked mechanosensory function of elaborate feather ornaments in birds. In 2007 Mr. Seneviratne returned to the same area to test his theory on other closely related species of auklets– the least and crested auklets. Of these the least auklet has no crest at all and for this experiment the pair gave the birds a faux crest by gluing feathers to it taken from the whiskered auklet.
“We wanted to see how they reacted,” said Mr. Seneviratne. “It was much like putting a collar on a cat, they didn’t freak out but the analysis showed that they didn’t know how to use it. We determined they did not have any significant reductions in the number of head bumps using the artificial crest. So it proved the validity of our previous experiment.”
Mr. Seneviratne is now looking these trait expressions across all bird species to see if there is a correlation between habitat selection and these types of trait expressions.