WICHITA, Kan. (Map, News) - The Flint Hills are no longer the "Prairie Chicken Capital of the World," because a combination of ranching practices, invasive trees and encroaching civilization is causing the birds' population to plummet, scientists say.

Studies from the Kansas Department of Wildlife and Parks show the number of prairie chickens in the Flint Hills' eastern edge has fallen 90 percent in the past 30 years and 50 percent throughout the rest of area.

"Prairie chickens are right at the top of our list of species we're concerned about," said Ron Manes of the Nature Conservancy of Kansas. "They are an excellent indicator of the health of the prairie."

Biologists fear that a decline in the prairie chicken could start a chain reaction that would also endanger the eastern meadowlark, Henslow's sparrows, grasshopper sparrows and others.

Prairie chickens are a robust species, able to roost in snow drifts in freezing weather and fly several miles between their nests and feeding areas. But they do require tall grass for their nests and privacy - they won't nest anywhere near trees or man-made structures.

But annual prairie burning, cattle grazing and other changes are making it tougher for the birds to find a home.

"We have a lot of annual burning now, and we don't have any (nesting) cover," said R.J. Robel, a biologist and researcher for Kansas State University. "It's a sad situation."

Prairie chickens once thrived in an area extending from Alberta to Texas and east to Ohio. Now, the majority of birds live in Kansas, Nebraska and South Dakota, said Bill Vodenhnal, a Nebraska biologist and coordinator of the Prairie Grouse Plan for North America.

In Kansas, which still allows prairie chickens to be hunted, hunters used to take 80,000 greater prairie chickens annually. In 2006, they shot about 6,000.

Other states, including Missouri, Oklahoma, Iowa and Illinois, are struggling to sustain or rebuild their own populations. Missouri even has imported birds from Kansas to replenish its stocks.

Experts said the decline came as farms, housing developments, roads and planted forests overtook what had traditionally been tall grass prairie. The Flint Hills region, which is inhospitable to farming, proved an oasis for the prairie chickens for many years.

But ranchers have increasingly begun relying on annual prairie burns to rejuvenate the land for cattle grazing. Kansas State University has recommended the burns to increase cattle weight since the 1960s.

Eureka rancher Wayne Bailey said he's been burning his prairie land every year for 40 years and sees his animals pack on an additional 25 to 55 pounds each. He said he doesn't believe the burning it hurting the prairie chicken.

Robel, however, said the grass in burned areas reaches only a few inches tall by nesting season, far shorter than the 18 to 20 inches favored by prairie chickens. He said hens that do lay eggs in the taller tufts of cover are in greater danger as predators have learned to look for that shelter on blackened prairies.

In addition, a study at Fort Riley in the 1990s found that the number of raccoons, opossums, skunks, pack rats and other mammals likely to prey on eggs or young prairie chickens was 10 times what it had been in the 1970s.

A Kansas State study has found that the survival rate of nests and chicks in the Flint Hills is now lower than 20 percent, Robel said.

"You need about 60 percent for prairie chickens to sustain themselves," he said.

Other studies show female prairie chickens avoid tall vertical structures, such as wind mills, and won't build a nest within 400 yards of major power lines, 850 yards of well-traveled roads or a quarter-mile of a house.

Not all those hazards are man-made. Experts say trees also spook nesting hens, possibly to avoid predatory birds, and cedar trees are encroaching on the Flint Hills' eastern border.

Biologists are looking for a balance between ranchers and the prairie chicken population.

Sam Fuhlendorf, a fire ecology specialist and wildlife professor at Oklahoma State University, said studies show rotating burns on designated areas of grassland every year, a practice called "patch burning," seems to provide enough land for cattle grazing and chicken nesting.

Jane Koger, who owns a ranch near Matfield Green, said she does patch burning but also tries to leave residual cover on some of her fields for prairie chicken nesting.

"I don't look at owning a pasture, I look at owning a natural resource," Koger said.

---

Information from: The Wichita Eagle, http://www.kansas.com