http://www.designfax.net/cms/dfx/opens/article-view-dfx.php?nid=4&bid=283&et=featurearticle&pn=03

In this age of advanced technology, how hard could it be to
develop a robotic bird that flies by flapping its wings? Despite the apparent
simplicity of the idea, it's very hard -- if you want the bird to actually fly.
And how hard could it be to make a robot bird whose wings can flap independently
of each other? So hard that this breakthrough has been out of reach for
engineers -- until now.

University of Maryland professors S. K. Gupta and Hugh Bruck and their students
have developed and demonstrated a new robotic bird, "Robo Raven," whose wings
flap completely independently of each other, and also can be programmed to
perform any desired motion, enabling the bird to perform aerobatic maneuvers.
This is the first time a robotic bird with these capabilities has been built and
successfully flown