Four-point Landing
Dog-faced fruit bats normally roost in leaves, where an animal can land as hard as it wants without fear of hurting itself. We found that these bats always landed very forcefully, with a peak impact force of up to >10x body weight. When they land, they grasp the surface with their thumbs and feet (four points) simultaneously.

Two-point Landing
Bats that roost in caves need to land gently, or they would risk injury. We looked at two species of cave-roosting bats, and found that both land very gently (peak impact force around 30% body weight). When these bats land, they grasp the ceiling with their feet only, not the wrists, so we called it a two-point landing.

Sucker-footed bats don't suck.
The Sucker-footed Bat of Madagascar, Myzopoda aurita, clings head-up to leaves when it roosts, by means of adhesive disks on its wrists and ankles. Until recently, these were thought to function by means of suction, but no one had investigated live animals to make sure. On a recent trip to Madagascar, we tested 28 individuals, and found that they don't actually use suction at all. Despite its name, the Sucker-footed Bat uses wet adhesion, just like like beetles, ants, tree frogs, and many other kinds of animals do.

Why do Sucker-footed Bats roost head-up?
When the pads of Myzopoda aurita are dragged backwards (posteriorly) along a smooth surface, they hold on well, but if the bat is pushed forward, the pads peel off easily. This probably helps them step forward when they walk, but is also probably the reason these bats have to roost head-up!

How do Sucker-footed Bats let go?
Sometimes when Myzopoda aurita detaches a pad from a surface, the central midline of the pad pops away first. We hypothesize that this is performed by the muscle that innervates the pad, called the Palmaris longus. This probably helps them detach quickly.

Bat in a Wind Tunnel
A bat in flight has around 20 joint angles per wing that it can manipulate. Just how they change those joint angles to produce aerodynamic force is one of the most basic questions in bat biology, but we still do not know the complete answer. By marking a wing with reflective paint, then recording flight at 1000 frames per second with multiple cameras, we can record changes in those joint angles as a bat flies, then correlate that with speed and acceleration.

Computer model of a flying bat
Based on the wing motions recorded in a wind-tunnel, we calculate what the predicted flow of air should be around the wings of a flying bat. This model was constructed by a fluids engineer, David Wills (University of Massachusetts, Lowell), and is part of a manuscript in preparation.

Flight of a very big bat
We have recorded the wing motions of bats up to 1.2 kg (2.6 lbs), with wingspans of up to 1.5 meters (4'10"). Because those bats are too large for the wind tunnel, we fly them down a hallway and record them with cameras on the floor as they go by. This video was recorded at the Lubee Bat Conservancy in Gainesville, Florida.

Flight of a relatively small bat
Many small bats, like the nectar-feeding long-tongued bats of Central and South America, are able to hover in place while feeding from flowers. This is a convenient system to study because you don't have to worry about thrust and drag, you can just focus on lift.

Running Vampire Bat
The common vampire bat is the only bat that runs. It moves unlike any other kind of tetrapod, since it powers the bounding gait with its muscular forelimbs. Vampire bats probably came from an ancestor that did not run, and evolved running on their own.

Walking Vampire Bat
The walking gait of the common vampire bat is very similar to that of a non-flying mammal, like a house cat or dog. These bats move the left forelimb with the right hindlimb, and vice versa. This is called a lateral-sequence walking gait.