How Long Do Bats Live? Surprising Lifespans of Small Bats

Typical bat lifespans

A bat’s lifespan depends on its species, its size, where it lives and whether it hibernates. Average lifespans in the wild are much shorter than record ages, because many bats die young, especially in their first winter. The table shows typical figures from banding studies and records.

These are approximate ranges. Records come from individual bats, so they show what is possible rather than what is usual.

The 41-year record

The oldest known bat was a male banded as an adult in a cave in southern Siberia and caught again at least 41 years later. Researchers published the find in 2005. The bat was recorded as a Brandt’s bat (Myotis brandtii), but populations from Siberia are now often treated as a separate species, the Siberian bat (Myotis sibiricus).

Either way, a mammal weighing about as much as two sugar cubes lived for four decades. That is roughly ten times longer than expected for a mammal its size, the biggest gap between body size and lifespan known among mammals.

Why bats live so long

Biologists have compared lifespans across hundreds of mammals. On average, bats live about three and a half times longer than non-flying mammals of similar size. Several factors seem to explain it:

• Flight and safety: flying lets bats escape many predators and roost in places predators cannot reach, such as cave ceilings. When a species faces fewer outside dangers, evolution favors bodies that last longer.
• Hibernation and torpor: bats that hibernate tend to live longer than those that do not. Spending months in a cool, low-energy state may slow wear and tear on the body.
• Slow reproduction: most small bats have only one pup a year, compared with litters of five or more for many rodents. Animals that breed slowly usually live longer.
• Cell repair: studies of long-lived bats have found effective DNA repair, protection of the ends of chromosomes, called telomeres, and strong defenses against damage linked to aging.

Researchers study bats to learn more about healthy aging, because some bat species show few signs of age-related disease even late in life.

Do bigger bats live longer?

In most groups of mammals, bigger species live longer: elephants outlive dogs, and dogs outlive mice. Among bats the rule is much weaker. Large fruit bats and flying foxes, which can weigh 1 kg (2.2 lb) or more, commonly live 15–20 years, but several tiny insect-eating bats weighing under 10 g have been recorded living twice as long.

What seems to matter more is lifestyle. Bats that hibernate and roost in caves, where the climate is stable and predators are few, include most of the record holders. Tropical bats that stay active all year and breed more often tend to have shorter lives. Species that give birth to twins or larger litters, such as some North American tree bats, also seem to live shorter lives than those that raise a single pup each year.

Why most bats die young

Despite the impressive records, the average bat lives much less than its maximum. The first year is the hardest. Young bats must learn to fly, hunt by echolocation and find suitable roosts. Many fail to store enough fat for their first winter of hibernation. Read more about winter survival in Do bats hibernate?.

Adults face dangers too: owls, hawks and cats; cold snaps that kill insects; loss of roosts in old trees and buildings; wind turbines; and road traffic. In North America, white-nose syndrome has killed millions of hibernating bats, so far fewer reach old age than before; see Why are bats dying in North America?.

How scientists measure bat age

Most information about bat ages comes from banding, also called ringing. Trained researchers fit a light numbered band to a bat’s forearm, release it and record the details if the bat is caught again. Some long-term projects have followed the same colonies for decades, which is how records of 30 and 40 years were found.

Scientists can also estimate the age of young bats from how fully the finger bones have grown and the wear on their teeth, and newer methods use chemical changes in DNA, called epigenetic clocks, to estimate the age of adults. Because bats are protected in Europe and in many US states, only licensed people may catch or band them.