This paper describes nonlinear control of a two degree of freedom mechanical system which models a bird perched on a branch or cable. The primary contribution is the implementation, in a controlled laboratory experiment, of the recently developed ℒ1 adaptive control approach. This technique, which allows fast adaptation with guaranteed stability margins, has been proposed for use in a variety of more sophisticated applications. Experimental results for this simple mechanical control system provide further motivation to pursue those applications. The system being considered is a variation of Spong's "Acrobot", a classic example of an underactuated mechanical control system. In addition to the ℒ1 controller, a swing-up controller based on Spong's original work on collocated partial feedback linearization is implemented with switching logic.