Use of Tail and Legs in Flapping in Bats

[Jaime Headden <qi_leong@hotmail.com>]

I'm surprised this wasn't mentioned, in all the brouhaha surrounding 
"Toroceratops."

http://10.1371/journal.pone.0032074

Adams, R. A., Snode, E. R. & Shaw, J. B. 2012. Flapping tail membrane in bats 
produces potentially important thrust during horizontal takeoffs and very slow 
flight. PLoS ONE 7(2):e32074. 

Abstract:
Historically, studies concerning bat flight have focused primarily on the 
wings. By analyzing high-speed video taken on 48 individuals of five species of 
vespertilionid bats, we show that the capacity to flap the tail-membrane 
(uropatagium) in order to generate thrust and lift during takeoffs and 
minimal-speed flight (<1 m s−1) was largely underestimated. Indeed, bats 
flapped the tail-membrane by extensive dorso-ventral fanning motions covering 
as much as 135 degrees of arc consistent with thrust generation by air 
displacement. The degree of dorsal extension of the tail-membrane, and thus the 
potential amount of thrust generated during platform launches, was 
significantly correlated with body mass (P = 0.02). Adduction of the hind limbs 
during upstrokes collapsed the tail-membrane thereby reducing its surface area 
and minimizing negative lift forces. Abduction of the hind limbs during the 
downstroke fully expanded the tail-membrane as it was swept ventrally. The 
flapping kinematics of the tail-membrane is thus consistent with expectations 
for an airfoil. Timing offsets between the wings and tail-membrane during 
downstrokes was as much as 50%, suggesting that the tail-membrane was providing 
thrust and perhaps lift when the wings were retracting through the upstoke 
phase of the wing-beat cycle. The extent to which the tail-membrane was used 
during takeoffs differed significantly among four vespertilionid species (P = 
0.01) and aligned with predictions derived from bat ecomorphology. The 
extensive fanning motion of the tail membrane by vespertilionid bats has not 
been reported for other flying vertebrates.

Cheers,

Jaime A. Headden
The Bite Stuff (site v2)
http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)