Bats in the wild live an average of 10 to 20 years. This depends on surviving to adulthood; young bats have a high mortality rate. After the first three weeks of life, they learn to fly, which improves their chances of survival.
An individual bat from a little brown bat species, Myotis lucifugus, was found to live for almost 40 years, which is a considerable outlier from average bat lifespans. Biologists generally agree that bats outlive other mammals of comparable size, such as rodents and primates. Bats are susceptible to some predations and to fungal parasites such as Pseudogymnoascus destructans, which is believed to cause a disease called white nose syndrome.