- The Greater Western Mastiff Bat (Eumops Perotis) is the largest bat species native to North America and can be found across southern Arizona - Weighs 45–85 grams with a wingspan of 20–23 inches (about the size of a medium potato) - Short brown or gray-brown fur, paler underside, large ears folded over the nose, and long, narrow wings - Emits an audible, low-frequency chirp every 2–3 seconds in flight that humans can sometimes hear