Newswise — It may be bad manners to ask people how old they are, but researchers at West Virginia University are examining ways to determine the age of birds.

A group of animal scientists in WVU's Davis College of Agriculture, Forestry and Consumer Sciences is looking at pentosidine as an indicator of just how long it has been since a bird hatched. Pentosidine is an end product of glycation, a process associated with aging in which proteins react with sugars.

"It's notoriously difficult to determine a bird's age," said Hillar Klandorf, professor of animal physiology in the Davis College and one of the authors of the text "Animal Physiology: From Genes to Organisms."

"After they reach adulthood, they go through very few identifiable physical changes," Klandorf added. "The traditional method of determining the age of birds is through banding, and that's very labor-intensive."

Pentosidine is very stable, accumulating in body tissues over time. It is also easily measured in a laboratory setting, he said.

"Pentosidine has been found to accumulate with age in the skin collagen of a variety of mammals," Klandorf said. "Comparisons from species to species of pentosidine accumulation have shown that it collects at different rates in different species, depending on their natural life span. The shorter the life span, the faster the pentosidine accumulates."

Klandorf, along with graduate student Jesse Fallon, U.S. Department of Agriculture wildlife specialist Brian Dorr and Davis College adjunct professor Bob Cochrane, conducted a study comparing pentosidine accumulation in two species of wild birds, the ruffed grouse and double-crested cormorant. They took skin samples of grouse of known age and simultaneously conducted a blind study of double-crested cormorants. Results indicated a direct correlation between pentosidine levels and age.

"Accurate age information could aid species recovery programs and provide insights into longevity, which is currently understood almost entirely from banding programs and captive birds," Klandorf said. "It could also provide insight into age-related population demographics such as the onset of sexual maturity and the effect of age on behavior and susceptibility to disease."

The WVU team built its research on single-species studies, choosing to do cross-species comparisons to gain a greater understanding of the differences between birds with different life expectancies. Their findings will be published in a series of articles in The Auk, the journal of the American Ornithologists' Union.

Grouse were chosen in part because of Cochrane's singular expertise with that species. He has been studying the ruffed grouse for many years and was instrumental in the construction of a grouse house on WVU's Animal Sciences Farm in Morgantown. He has also contributed a great deal to the body of knowledge pertaining to raising grouse in captivity.

In a separate study the researchers determined the concentration of pentosidine in preserved study skins of birds.

"Pentosidine was found to remain stable in the skin, which means that age estimations could be made on birds stored in museum collections," Klandorf said. "Imagine being able to take a piece of skin from an extinct bird such as the dodo or from a deceased California condor and being able to provide an estimate of its age at the time of death."

Fallon, who was an employee for WVU Libraries during his studies, has since completed his master's degree in animal and veterinary sciences and begun veterinary school at Virginia Tech. He found the project rewarding on a number of levels.

"I was fortunate to get involved with the research when I did," Fallon said. "Hillar Klandorf and I had the opportunity to work with some great folks, and we have made some real progress. Personally, my work with Dr. Klandorf has helped to open the door to veterinary school as well as other research projects."

He is also proud of his contribution to the knowledge base.

"Being able to determine the age of unbanded, adult birds will contribute to our understanding of population demographics and hopefully assist with the reproductive success of species survival programs working with critically endangered avian species," he said. "Ultimately, we would like to see the practical application of this technique by biologists in the field. Really, it's for the birds."

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