INTRO: Finding a suitable mate is a challenge for just about every species. If you're a seabird like the crested auklet, finding a partner may be as simple as being good at keeping parasites off your body. Doug Schneider has more, in this week's Arctic Science Journeys Radio.
STORY: Alaska's Aleutian Islands stand like lush, green sentinels overlooking the Bering Sea. Their massive cliffs are an oasis amid a vast, lonely ocean, and are home to a variety of seabirds. The most recognizable is probably the tufted puffin. These islands also are home to colonies of shearwaters, kittiwakes, and crested auklets. At seven inches in length, crested auklets aren't big. But what they lack in size, they more than make up for in number. Hector Douglas is a graduate student who studies crested auklets at the University of Alaska Fairbanks.
DOUGLAS: "Years ago, when I first started working in the Aleutians, I went out to a colony of auklets on Kiska Island, which is toward the western end of the Aleutians. One of the largest seabird colonies known to science occurs there. Well, it was quite an amazing introduction to the Aleutians, to be in the midst of this colony comprised of approximately 2 1/2 million auklets. To be sitting there early in the morning and to watch the fog lift off the water and see this mass of auklets rise up off the water in a long, black, sinuous cloud was really amazing. They are very peculiar-looking birds. They have a crested set of feathers that extends from the forehead and droops in a long arch. And they have this bright orange bill and this conspicuous white facial plume."
While at the seabird colonies, Douglas noticed a pungent citrus smell in the air. The odor emanated from the birds themselves, but no one knows for sure its purpose. Recently, Douglas isolated a series of chemicals, called aldehydes, that work together to emit the fruity odor. The findings are to be published in the June issue of the German scientific journal Naturwissenschaften. The publication is similar to the international journal Nature.
DOUGLAS "What we think we see is a rare example of a bird adapting a chemical defense. Our hypothesis is that it provides a repellent function against parasites."
Given that auklets live in massive colonies cramped onto steep, narrow ledges, such defenses would be a practical solution to the pitfalls of colonial living.
DOUGLAS: "They nest in very large colonies, thousands to hundreds of thousands. When you have such large colonies, you have the opportunity for a parasite population to actually become established and have an effect on the size of the colony in terms of limiting group size."
Yet Douglas suggests these chemical defenses play another, equally important role—that of helping auklets select a worthy mate. He says auklets are first attracted to a prospective mate's crested head plumage, but discriminating auklets don't commit to a lasting relationship until they check out their partner's odor.
DOUGLAS: "There is a part of the courtship ritual that appears to promote odor assessment. The prospective mates will actually rub their bills in the nape feathers of their mate. We suspect the birds will advertise their parasite resistance, and that the prospective mate can then determine, in a sort of honest way, just how resistant the mate would be."
Douglas hopes to conduct research to discover exactly what role odor plays in the crested auklet's ability to both combat parasites and attract a mate.
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.
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Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.
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Crested Auklet (U.S. Fish and Wildlife Service)