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.
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.
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.
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.