Bird vomit is turning out to be a valuable research tool for scientists like the University of Virginia's Charles Clarkson, who is often covered with avian upchuck at the end of each work day in the field.

(Charles Clarkson analyzing bird vomit; Credit: University of Virginia)

Clarkson and others analyze the regurgitation, as he politely calls it, to determine bird diets, presence of pollutants, and other information. For example, Clarkson is now amassing an extensive collection of bird barf for a comparative study of bird populations on Virginia's Eastern Shore and in New York Harbor.

It's not too hard to get the stuff.

The glossy ibis and the double-crested cormorant, two birds included in his latest study, produce nestlings that vomit as a defense mechanism.

"It

makes my job easy because I can go into a colony, pick up the nestlings

and they will regurgitate into a bag for me," he said, adding that he also collects feathers from the birds while in the field.

(Glossy Ibis; Image: Wikimedia Commons)

(Double-Crested Cormorant; Image: Wikimedia Commons)

Back at the lab, he can determine which

species of fish were consumed, and the diversity and apparent abundance

of those species. He can also assess the mercury levels in those foods

and, therefore, the birds' diets.

"I can tell a lot about the

environments in which they live and, likewise, the overall health of the

overall environments in which we all live," he said. "I also can

analyze feathers and determine if these feathers are growing normally or

at a slower rate and if they're denuded. I can correlate that with the

diet the bird is getting, and the contaminate load that the bird is

getting as well."

He added, "Initial indications seem to be that the feather

growth bars are wider in Virginia birds than New York birds, which

likely means better nutritional conditions on the Eastern Shore, whether

from dietary abundance or quality."

The New York birds also seem to be more stressed out.

"Fault

bars" – thin patches in their feathers- are present. These suggest a variety of

stresses, such as predation and disturbances from human activity, are affecting the big apple birds.

"Fault

bars mean that nestlings are devoting more of their energy resources to

immuno-suppression than to feather growth," Clarkson explained. "So the

feather has less actual substance to it."

The findings match his predictions. The Eastern Shore site is in a nearly pristine area that has been protected by the Nature Conservancy for 40 years. In contrast, the New York Harbor site is heavily polluted and is adjacent to the activities of an enormous human population.

"There's heavy boat

traffic at the mouth of the Hudson River, which is notorious for

high-level contaminates, such as mercury," Clarkson said. "This allows a

good comparative study between two vastly different locations that

support the same species of birds."

I wonder if mercury levels would differ from the upchuck of Virginia people versus those from New York? And if hair from residents of each of these places would show distinct levels of stress-related hormones?

As hard and unappetizing as Clarkson's work is, analyzing birds is probably easier and just as revealing about the two environments selected for his study.