A rare white bison that’s sacred to Native Americans was born in Yellowstone National Park for the first time earlier this month — but hasn’t been seen since. The National Park Service on Friday confirmed the extraordinary June 4 arrival of the calf, citing “multiple creditable sightings” and photos shot by park visitors, professional wildlife watchers and others. But there haven’t been any confirmed sightings since then, and park workers have been unable to locate the baby bison, the NPS said in a news release. About one in five bison calves are killed by “natural hazards” each spring in Yell…