Bigger feather crests in male seabirds reflect their suitability as mates.Byline: ANI Washington, Apr 17 (ANI): The size of males' feather crests in a breed of northern seabird is not just simple ornamentation ornamentation In music, the addition of notes for expressive and aesthetic purposes. For example, a long note may be ornamented by repetition or by alternation with a neighboring note (“trill”); a skip to a nonadjacent note can be filled in with the intervening , but a physical indicator of the bird's quality as a mate, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. a study by researchers at the University of Alaska Fairbanks UAF is home to seven major research units: the Agricultural and Forestry Experiment Station; the Geophysical Institute, which operates the Poker Flat Research Range; the International Arctic Research Center; the Arctic Region Supercomputing Center; the Institute of Arctic Biology; the . For a long time, scientists have known that female auklets prefer males with larger crests, but they have been unaware of the reason behind it to date. The new study has shown that low levels of stress hormones in males with larger crests indicate that they cope better with the stresses of reproduction, like finding food, competing with thousands of other birds for mates and nest sites, and helping rear chicks. "Females will divorce shorter-crested mates for the opportunity to mate with longer-crested males. Our study suggests that longer-crested males could contribute more to reproductive success Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. because they have greater capacity to meet the social and physiological costs," said Hector Douglas, assistant professor of biology at the Kuskokwim Campus in Bethel. The researchers claim that their results fit into a larger theory about animal societies. Douglas said: "There appears to be a social hierarchy Social hierarchy A fundamental aspect of social organization that is established by fighting or display behavior and results in a ranking of the animals in a group. at the colony which is correlated with the size of the male ornament and this, in turn, is related to the levels of stress hormones. The cost of attaining and maintaining dominant status is reflected in the animals' physiology and this has a distinct pattern in the society." For the study, the researchers examined the small, sooty-gray seabirds during fieldwork on Big Koniuji in the Shumagin Islands The Shumagin Islands are a group of 20 islands in the Aleutians East Borough south of the mainland of Alaska, USA, at 54°54'–55°20' North 159°15'–160°45' West. The largest islands are Unga Island, Popof Island, Korovin Island, and Nagai Island. in the Aleutian Chain during June and July of 2002. They captured and measured the auklets at a mountainside colony and collected blood samples. After analysing the blood samples for the stress hormone corticosterone corticosterone (kôr'təkōstĕr`ōn), steroid hormone secreted by the outer layer, or cortex, of the adrenal gland. Classed as a glucocorticoid, corticosterone helps regulate the conversion of amino acids into carbohydrates and , it was found that larger crests correlated with lower levels of corticosterone in the males' bloodstream. "Theoretically males that have a lower level of baseline stress hormone have a greater capacity to respond to additional stress. The males with the larger crests had markedly lower levels of corticosterone and therefore they should be better mates. We suspect that crest size is an outward indicator of intrinsic quality, and the data on hormones appears to confirm this," said Douglas. The study has been published this month in the Journal of Comparative Physiology B. (ANI) Copyright 2009 Asian News International The Asian News International (ANI) agency provides multimedia news to China and 50 bureaus in India. It covers virtually all of South Asia since its foundation and presently claims, on its official website, to be the leading South Asia-wide news agency. (ANI) - All Rights Reserved. Provided by Syndigate.info an Albawaba.com company |
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