From mid-March into May, male greater prairie-chickens gather on patches of bare or short grass in the Flint Hills and display for the females. They inflate the air sacs on the sides of their necks and snap their tails, and the display grounds are called booming grounds, or leks. Ten to fourteen males held each of the four leks that Kansas State University researchers watched in Riley and Geary counties from 2003 to 2006, one of them on Konza Prairie. A female visits a lek only to mate. She then builds a nest alone, lays about eleven eggs, one a day, and incubates them for twenty-three to twenty-five days. The chicks stay with her for nearly three months.
The Flint Hills hold one of the largest populations of greater prairie-chickens left on the continent, because they hold most of the tallgrass left. Tallgrass prairie once covered about 170 million acres from Canada to Texas, and about 4 percent of it survives. Roughly two-thirds of what remains in North America is here, kept in grass because the rocky hills were never worth plowing. Prairie-chickens in Kansas declined by about 70 percent over the last two decades of the twentieth century, and researchers have tied the drop to a change in how the pastures are run.
Every spring
Fire and grazing are not the problem in themselves. The state's smoke plan calls them essential ecological processes, and the prairie needs fire to keep trees out. What changed was frequency. Ranchers moved from burning every few years and grazing moderately toward burning every spring and stocking cattle heavily for the first half of the growing season, a system called intensive early stocking. Satellite images from 2003 to 2006 showed about 1.67 million acres burning in an average year across fourteen Flint Hills counties, most of it from late March to early May, and the most intact pastures burned most often. That is early in the nesting season, and a pasture burned and grazed short every year leaves no old grass to hide a nest in.
The nests
Of the 34 nests the researchers followed, 27 failed: predators took 85 percent of those and prescribed fire destroyed 11 percent. The predicted success of a nest over its 35 days of laying and incubation was 7.4 percent. Hens that lost a first nest often tried again, sometimes moving long distances to find unburned cover, and their second nests did better. The authors wrote that burning less often, or in other seasons, would cost fewer nests and help the air downwind.
The smoke
The air was what moved policy. On April 12 and 13, 2003, smoke from the Flint Hills helped push ozone at three Kansas City monitors over the federal standard, and complaints came in from as far as Tennessee. Kansas wrote a Flint Hills Smoke Management Plan in December 2010, and its website now posts a daily smoke forecast for burners. The plan listed burning's effect on prairie-chickens as a question still needing research. One practice it discussed, patch-burn grazing, burns about a third of a pasture each year and leaves the rest standing as cover.