This is a big brown bat, native to most of North America, Central America, and the far north of South America. He came in malnourished and with a bit of an infection about a week ago. Big brown bats are insectivores, catching prey such as moths, wasps, and mosquitoes while in flight. They are mostly active at night, and hunt using echolocation. This means that they emit a high frequency sound, and then interpret their surroundings based on how the sound bounces back to them off of objects. This guy is responding well to medication, and should soon be completely healthy.