Last week it was time for the annual nitty-gritty of bison herd maintenance at the Nature Conservancy's Tallgrass Prairie Preserve. It was time for weighing and shots and the inevitable decisions about which bison will be around for the next roundup, and which ones may be on the way to the great bison herd in the sky. Katie Hawk, spokeswoman for the Nature Conservancy, drew attention to the artful skill with which the ranch hands working the annual roundup use their trucks to "dance" across the prairie and drive the bison into a holding pen just after first light...
