Colorado Division of Wildlife data show bighorn numbers statewide decreased by 10.2 percent between 2001 and 2009 ˜ from 7,690 to 6,903. Construction carving into their habitat and disease attacking their lungs ˜ combined with vehicular traffic and livestock ˜ are identified as stress factors. Hunters kill an average of 157 bighorns a year. Federal biologists contend that competition from mountain goats ˜ introduced in 1948 by Colorado wildlife managers ˜ could push bighorns over the brink. The most heralded herd of 335 bighorns above Georgetown ˜ the one along Interstate 70 that people snap pictures of ˜ is producing only 10 to 12 lambs per 100 ewes, said Rick Kahn, terrestrial- wildlife-management supervisor for the state. That is less than one-third of what a healthy herd should produce. "It's fair to say that, of all the big game in this state, the bighorn species is the one we are most concerned about," Kahn said.