As dusk settled over Gainesville on a November night, a handful of people gathered behind fences enclosing an open field on Museum Road, waiting. Bundled in blankets, they stood with their eyes glued to two bat houses in the field, searching the dark sky for bats and expecting a show that has become a popular Gainesville must-see. But the show they got was perhaps not what they had hoped for, as hundreds of bats have disappeared from the houses, leaving experts, biologists and bat fans wondering where they went.