PHOTO FEATURE Aromatic Sea K.S. Someswara

N the year 1918, the US Migratory Treaty Act was birds had a sense of smell which is a radical one, let alone passed to protect birds from wanton killing. Year 2018 is the notion that perfumes could function as a signal of fitness Ithe centennial year of the Act. We humans do have a body odour when we sweat, but The National Geographic along with the National Audubon certainly they are not aromatic. In order to beat the odour, we Society, BirdLife International and Cornell Laboratory of use varieties of perfumes and colognes. This will be different Ornithology declared 2018 as the Year of the Bird. They signed for men and women. Sometimes persons are identified with a pledge to chalk out action plans in this direction. the cologne they apply on their bodies. Researchers have long known that male auklets with One summer Douglas captured dozens of crested auklets larger crests – a tuft of head feathers that curl forward – have on the Shumagin islands and inserted them one by one into a more sexual approach. But, unlike an elaborate display or a specialised chamber to quantify their scent. A stream of vocalization, this ornamental cosh is an unreliable signal purified air was passed around the birds’ body picking up of fitness for females looking for a robust male. Scientists volatile molecules that produce the aroma which was then assumed that there must be something else that makes these filtered and analysed. These organic compounds – aldehydes – larger-crested individuals attractive. are found in citrus fruit rinds, as well as off-the-shelf perfumes. Auklets make their own citrus scent cologne. Male crested Before releasing them back to the wild, Douglas measured auklets have large head feathers and a strong tangerine smell, the bird’s fitness through a stress response hormone called confirms a new study. The new research in Behavioural corticosterone. This is the bird equivalent of cortisol. The Ecology reveals that it is the strength of this citrus scent along faster the birds produce hormones the stronger their physical with the size of their crusts that really matter. condition. Perhaps it is their smell, says the study leader Hector Back on his research table, ‘an exalting pattern emerged’ Douglas, an independent marine biologist. “The citrus odour he says. Birds with larger crests produced a higher quality is increasingly intense,” he says. According to him, they are of citrus perfume. This indicates that odour is attractive to the strongest smelling birds. females. “Something happened in evolution to favour the In 2002, when he began the research, he had no idea that production of this chemical,” says Douglas.

Rhinoceros auklet Parakeet auklet

34 | Science Reporter | October 2018 Whiskered auklet

Least auklet

More than that, more citrus auklets release corticosterone at a faster rate suggesting that the auklets’ capacity to produce perfume is tied to their physical ability and their fitness. These birds have come up thousands of feet above sea level and have to evade eagles and Peregrine falcons to get to their nests. Increasing fitness likely leads to larger and more successful broods, feels Douglas. Theresa Jones, a biologist at the University of Melbourne who was not involved in the research, likes the male bird’s odour production to a ‘badge of statics’. It is a ‘Magic Musk’ she says. It is an interesting one, because there is an underlying cost to production she says – not unlike the energy required by male birds to put an elaborate courtship display and songs. The odour secreted through the feathers in the male’s necks can slow or paralyse bloodsucker pests such as lice, mosquitoes and ticks. And on Shumagin’s island, that is no small benefit as Douglas observed about ten ticks crawling up his legs. When it comes to the family of Crested Auklets they are small sea diving birds called Alcidae. Its biological name: ceistatellia. They can be seen throughout the Pacific and Bering Seas. They feed by diving into the deep sea eating and a variety of small marine . They nest in dense colonies of up to one million individuals. Sometimes they breed in mixed species. Their life-span is about seven to eight years. Crested auklets are known for their forehead crests made of black forward curving feathers. Each will have an average of 12 crest feathers of variable length of 8 to 8.5 mm. The odours are generated from tiny wick feathers in a small patch of skin in between the shoulder blades. Every day they circle 500 metres above sea and breeding colonies. They forage in deep waters for their food, but an area close to shore and always move in flocks. A variety of marine invertebrates are their diet. They are highly sociable and responsible parents.

K.S. Someswara, No.12/B, 6th Cross, Lake City Layout, Kodichikkanahalli, Bengaluru-560076; Email: [email protected]

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