THERMAL IRRADIATION PREFERENCES OF WHITE-CROWNED SPARROWS IN RELATION TO AMBIENT-TEMPERATURE

Various aspects of behavior of White-crowned Sparrows in an irradiation perference unit were examined. Included were influences of the preference cages themselves, orientation in the room, illumination, and temperature-irradiation intensity combinations. Of these, temperature and thermal irradiation had the most pronounced effects. At low temperatures birds spent a relatively large fraction of their 480 min photoperiod in environments of moderate irradiation intensity and a smaller fraction at a higher intensity (e.g., mean values at 5°C: 188 min and 96 min in 1.0 and 0.4 gcal/cm2-min, respectively; and 67 min in 1.7 gcal/cm2-min). At higher temperatures the birds spent less time in the irradiated environments (e.g., mean values at 30°C: 6 min and 33 min in 1.0 and 0.4 gcal/cm2-min, respectively). Instead a larger proportion of time was spent in the air stream (e.g., 196 min vs 42 min at 30°C vs 5°C, respectively). Time intervals spent in irradiated environments were generally longer at lower temperatures than at higher temperatures. Interpreted jointly with measurements of oxygen consumption as a function of air temperature and irradiation intensity, the data show that White-crowned Sparrows have sensitive powers of behavioral thermoregulation with respect to incident radiation. © 1979.