Foraging Behavior Experiments (May 1980-May 1981) White-throated Sparrows are common birds of North America and tend to build their nests on the ground in lightly forested areas between clumps of vegetation (5). These birds are primarily ground feeders; they depend largely on uncovering food by scratching on the ground, an activity that they engage in for prolonged periods of time (5, 6). Birds were exposed to microwaves and measurements were made on various parameters of their foraging behavior. White-throated Sparrows were collected in May and October, 1980 at Manomet Bird Observatory. They were housed for at least three weeks prior to the initiation of training and between treatments in cages (43 x 33 x 59 cm) framed of metal or wood, and enclosed with plastic screen (mesh 12.7 x 12.7 mm). They were fed a diet consisting of wild bird seed, alfalfa sprouts, broccoli, cabbage, hard-boiled eggs, egg shells, and mealworm larvae. A vitamin supplement was administered either in water or as a dry powder added to their food. Food was provided ad libitum except during the foraging experimental regimen. During August to December the birds were maintained on a natural light cycle. The light cycle from January to March was increased weekly by 15 minutes until a 12:12 light/dark cycle was achieved. This 12:12 schedule continued unchanged through the completion of the experiments in May 1981. The 12:12 schedule was required to accommodate other experiments conducted in the same facility. Birds were trained to forage for mealworm larvae (Tenebrio spp.) from a specially designed foraging tray (36 x 61 cm). Trays were constructed of Ensolite® boards with 50 cylindrical cavities, each 8 mm in diameter and 13 mm deep. The cavities were arranged in a uniform grid formation with distance between the centers of the cavities 7.5 and 5.5 cm for horizontal and vertical rows respectively. A foraging tray was prepared for a training session by initially filling each cavity with a single mealworm. Through progressive trials the wells were first partially then completely covered by an adhesive label (19 x 12.5 cm).
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