Leg Thrust Important

This paper talks about importance in leg thrust during a birds take off.

http://jeb.biologists.org/cgi/reprint/114/1/285.pdf

A very nice paper, provided good information like bird generates force nearly 1.6 times of its body weight.

Also, it introduced me to concept of clap-and- fling.

Other things like bird of a pigeon is around 300 gms was one I was looking for.