What's more, the network of muscles that crisscross the patagium can reshape the squirrel's "wings," creating a dynamic surface.
Squirrels can even fly upward and increase their speed. They do this by carefully controlling the air that swirls on either side of their patagia. Vortices of turbulence on top of their patagia are tamed with special hairs on their shoulders that they raise and lower. Squirrels can also direct air under their patagia, giving them lift.
"They're really good at directing airflow," Badyaev said. "That's a good compensation for lack of flapping. They're probably better at it than bats. Bats are maneuverable, but that's because they flap like crazy."
In contrast, like an airplane that is able to alter its wings midflight, flying squirrels continually adjust their patagia.
Badyaev made other observations. Since flying squirrels are clumsy and vulnerable on the ground - they have to drag around their parachute-like patagia - they are able to leave it quickly. They use their muscular hind legs to leap into the air, gaining altitude before unfurling their furry wings and gliding away.
"It turns out their jump up is incredibly powerful," Badyaev said. They routinely leap vertically seven feet, bursting from the snow and creating a sound that Badyaev likened to a champagne cork popping.
Badyaev's work is a testament to hours spent in the field - and to the flying abilities of squirrels. Perhaps aeronautical engineers could even learn something.
"I don't know if putting mittens on wings of aircraft would work," Badyaev joked. "That's what squirrels do."