Bats are the only living mammals capable of sustained powered flight.

Powered flight requires an animal to generate aerodynamic forces by actively moving its wings. Bats do this with muscular wingbeats, allowing them to maintain flight instead of relying on a single descending journey from a high launch point.

A bat wing is a modified mammalian forelimb. Long finger bones spread out beneath a thin skin membrane, and the many movable joints let the animal alter the wing shape as it flies, rather than holding a rigid surface against the air.

Flying squirrels illustrate the distinction. Their stretched skin helps them glide between trees, but they do not use repeated wingbeats to sustain powered flight. Sharing the air with bats does not mean sharing the same method of aerial movement.

The scientific name of the bat order, Chiroptera, means "hand wing." The National Park Service invites readers to imagine a human hand with much longer fingers and enlarged, thinner skin stretched between them. That comparison captures the basic skeletal relationship without suggesting that bat wings are merely human hands with extra skin.

The membrane and its supporting joints give bats considerable control over their flight surfaces. The shape can change through a wingbeat, helping produce the maneuverability visible when an insect-eating bat turns, swoops, or intercepts prey. These are working, adjustable wings, not passive parachutes.

The National Park Service illustrates this agility with footage of a big brown bat pursuing a luna moth and a red bat catching moths with an aerial backflip. The first encounter also shows that pursuit is not automatically successful: a moth can have defenses that make capture difficult.

Flight and finding prey are related but separate capabilities. Many bats use echolocation, emitting sounds and interpreting returning echoes to obtain information about nearby objects. Wing movement supplies locomotion; hearing the echoes helps guide it. Echolocation does not replace the aerodynamic work of moving through the air.

The familiar image of a bat chasing insects describes many North American species, not every bat everywhere. The National Park Service specifically identifies insects as the primary food of most bats in North America. The flight distinction applies to living bats as a mammalian group, regardless of the food a particular species eats.

Powered flight means producing aerodynamic forces through repeated wing movement, not merely traveling through air. Gliding mammals can control a descent, but their membranes do not turn that descent into a bat-like sequence of sustained wingbeats. The distinction is mechanical, not a judgment that one form of locomotion is better. Both solve movement problems under different constraints.