" Bats come in many, many forms. The order Chiroptera (the “hand-wing” creatures) encompasses 1,116 species, which amounts to 25 percent of all the recognized species of mammals. To say again: One in every four species of mammal is a bat. Such diversity might suggest that bats don’t harbor more than their share of viruses; it could be, instead, that their viral burden is proportional to their share of all mammal diversity, and thus just seems surprisingly large. "

― David Quammen , Spillover: Animal Infections and the Next Human Pandemic