Megabat . The megabat family, Pteropodidae, includes the largest bat species, some weighing up to 1.45 kg (3.2 lb) with wingspans up to 1.7 m (5.6 ft), as well as smaller species, some less than 50 g (1.8 oz). They are found in tropical and subtropical areas of Eurasia, Africa, and Oceania. Unlike other bats, they have dog-like faces and clawed second digits. Well-adapted for flight, megabats have sustainable heart rates of more than 700 beats per minute and large lungs. Most of them are active at night. They roost in trees or caves, sometimes in colonies of up to a million individuals. Most are unable to echolocate, relying instead on their keen senses of sight and smell to navigate and locate food, usually fruits or nectar. A quarter of all megabat species are listed as threatened, due mainly to habitat destruction and overhunting. Even though they can transmit a variety of dangerous viruses, they are a popular food source for humans in some areas.