Billings, Mont. -- Most elk, bison and trumpeter swans are unfazed by the presence of snowmobiles in Yellowstone National Park, a new study suggests. Researchers from the park and Montana State University observed more than 2,100 interactions between snowmobiles and wildlife last winter. In 81 percent of the interactions, the animals either had no apparent response, or they looked and then resumed what they were doing, the study said. The study, commissioned by the National Park Service and conducted between December 2004 and March 2005, is one of several that park officials say they will take into account as they...