number of prey caught per second of foraging (searching + handling time), and search efficiency, defined as number of prey captured per second of search time, were calculated. White-throated Sparrows were exposed for seven days at one of four power densities (0.1, 1.0, 10.0, and 25.0 mW/cm2). One bird was exposed at each microwave power density and two additional birds served as parallel sham controls (0.0 mW/cm2). Microwave-treated birds were irradiated 24 hrs per day except for brief periods during each day when maintenance activities were performed or when being prepared for observations of foraging behavior. The duration of each experiment was three weeks; e.g., seven days pre-exposure, seven days exposure, and seven days post-exposure. Foraging behaviors were observed three times per week while the birds were being irradiated. Each bird was housed in a replicate of the observation cage (Fig. 2). and tested in the same cage and chamber in which it was housed. Seed dispensers, water tubes, and vegetable cups were provided except during testing and for 2 hrs before. Experimental and sham control birds were selected randomly, weighed, returned to their cages, and tested. Once all birds were tested the random selection process began again. The cages were placed in control chambers during the pre-exposure weeks, in irradiation chambers during exposure weeks and in control chambers during post-exposure weeks. Parallel control sham birds (0.0 mW/cm2) were housed in control chambers during all three periods. Ambient temperature measurements were taken both inside and outside of the exposure and control chambers. This experiment was replicated once (accounting for the 6 trials per exposure period reported for microwave exposed birds in Table 1).
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