thousands of bats in huge caves

thousands bats huge caves southeast asia animals hang ceiling cave eyes glow searchlight mass carrier infections dangerous coronaviruses diseases human diseasesampling organism disease conductor covid sars coronavirus bat big brown biophysics dwellers cavedweller cheiropterous common vectors dungeon hibernation infection mammals mouse nature radar sleep sonar speleobios speleology spelunking subterranean suck blood ultrasound unpleasant vampire vespertilionidae winghanded glowing