Measurements of foraging behavior were made as follows. Each bird was released into a specially designed microwave transparent cage (0.9 x 0.9 x 0.44 m) constructed of nylon netting and plexiglas® (Fig. 2). Cages were divided in half by a visually opaque wall. One half was a waiting arena. The other half served as a foraging arena. Access from the waiting arena to the foraging arena was through a manually-operated door. Each half cage allowed independent placement and removal of foraging trays. For each experiment a foraging tray was prepared by randomly placing one mealworm, treated previously with hot water to immobilize them, in 25 of the 50 available cavities, respectively. An opaque adhesive label was placed over each of the 50 cavities to conceal the wall. The tray was placed into the foraging arena 15 minutes after the bird entered the waiting arena space. The door in the opaque divider was opened manually permitting the bird to enter the foraging arena. Search time, handling time, and nonforaging time were recorded to two-second intervals for 15 minutes using a Rustrak event recorder. Profitability, defined as
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