Sunday, October 24, 2010
Their eyes are on the sparrow
Radford University researchers are trying to catch the cagey house sparrow to study the effects of stress on the birds' immune systems and behavior.
Photos by JUSTIN COOK The Roanoke Times
Behind the Fairlawn Kroger, Radford University students (from left) Jordan Cohen, Clint Lexa and Sarah Foltz and professor Jason Davis (with binoculars) are on the lookout for house sparrows capture for a study on stress hormones.
Radford University biology professor Jason Davis will observe and analyze hormone and immunity activity in the sparrows he and his students trap.
| Tonia Moxley
FAIRLAWN -- Life has always been hard for immigrants.
From detention camps and exclusion acts to border fences and labyrinthine visa rules, it's never been easy to settle in a new land.
But not so for the ubiquitous house sparrow.
Love for the little black and brown striped bird common in grocery store parking lots and around restaurant trash receptacles can be as hard to find as the elusive, ivory-billed woodpecker.
But even though federal and state laws encourage their eradication, house sparrows (misnamed, because they are technically a species of weaver finch) thrive.
Imported from Europe and native also to Asia, the house sparrow has been a resident alien in America since a small colony set up housekeeping in Brooklyn, N.Y., in 1851.
Today, the species' range extends to every state in the U.S., north into Canada and south to Central America.
In fact, they can be found on every continent except Antarctica, and are considered the most widely distributed bird species in the world.
"They're tough. They're scrappers. They're city kids," said Jason Davis, a Radford University biology professor.
Davis and a group of student researchers gathered behind the Fairlawn Kroger this week to try and catch about 50 of the birds for a study of the effects of stress hormones on the birds' immune systems and behavior.
This research is being duplicated by other scientists and someday could be applicable to humans, said Sarah Foltz, a Virginia Tech biology graduate student helping with the Radford study.
Though disliked, even hated by advocates of native birds, some have come to admire the house sparrow for its tenacity, sheer grit and surprising intelligence.
"They're smart," Davis said.
He knows because even after baiting the birds for days with high-quality seed, they meticulously avoid the mist net and sparrow traps set out by him and his students.
"They fly right up to the net, then stop and walk under it," Davis said. "After a while you start to think they're doing it on purpose."
House sparrows have been observed opening electronic shop doors to get to food. One was seen last week inside a Blacksburg Kroger pecking crumbs off a table.
They nest practically anywhere -- including the crook of a letter in the Christiansburg Barnes & Noble sign -- and build their nests with all sorts of materials, from dried grasses to shredded cigarette butts.
House sparrows steal food from other birds and evict competitors, such as bluebirds, from nesting sites -- a fact that irritates bluebird enthusiasts.
Native bird advocates regularly destroy house sparrow nests and eggs found in boxes erected to encourage bluebirds to breed.
Unlike most non-game wild birds protected by strict laws, the house sparrow is considered a pest species -- along with starlings and pigeons -- and may legally be exterminated.
But those efforts have not slowed the scrappy bird's spread.
It, like the humans it prefers to live with, can adapt to nearly any environment. And its abundance and knack for survival makes the house sparrow well-suited to biological study.
"With these guys we can see what's really going on in the real world," Davis said.
As recently as 20 years ago, most research was limited to laboratory rats bred in captivity and monitored through extensive handling by humans.
But wild birds shaped by natural environments and observed remotely by robotic systems may provide a more nuanced picture of biological processes, Davis said.
Once Davis and his students catch some house sparrows, the birds will be transferred to a new aviary at Selu, a research and retreat center owned by Radford University.
There Davis and Selu manager Jeff Armistead have built a state-of-the art research aviary with robotic feeding and monitoring systems. It can house several hundred birds at a time, even separating them into groups so scientists can conduct different studies simultaneously.
Tiny transmitters can be injected into each bird to monitor food intake, hormone levels and other information, which can be shared online with students, faculty and other researchers.
At Selu, Davis' group will observe and analyze hormone and immunity activity in individual birds.
The study of how house sparrows deal with stress hormones may one day lead to better treatments for stress-related illnesses in humans, University of South Florida biologist Lynn "Marty" Martin said.
Martin oversees a large research laboratory devoted to the house sparrow.
Before modern civilization mitigated threats such as starvation, predator attack and exposure to extreme weather, humans evolved in environmental contexts similar to house sparrows.
To survive, humans, like the birds, developed stress response systems that helped them avoid predators (or university professors). But today, those same systems, when triggered by run-ins with a demanding boss or problems at home can, over time, make people sick.
"But it doesn't have to," Martin said.
Studying the birds' stress response "could shed light on why stressors impact humans the way they do," Martin said.
See, hear and learn more about house sparrows at www.allaboutbirds.org/guide/House_Sparrow/lifehistory