Fig. 1. The experimental equipment consisted of a cage constructed from Perspex with flexible plastic bristles at the bottom, a feeder with sucrose solution and two perches. The main perch was suspended from an electronic balance, interfaced to a computer. The vertical feeding perch had pins inserted to discourage prolonged resting. An infrared photo-detection system, interfaced to the same computer, was mounted on either side of the feeder in order to record feeding events. One-way mirrors on two sides of the cage allowed observation of the bird with minimal disturbance.