Adult American toads, Bufo americanus americanus Holbrook, may be exposed to conditions that result in considerable variation in both body temperature and hydration state during their daily activity periods. We measured the interactive effects of body temperature and hydration state on locomotor performance of toads. Performance, measured as distance moved in 10 min of forced locomotion, decreased at all body temperatures as animals were dehydrated. The magnitude of this decrease was affected by temperature. Similarly, the effects of temperature on performance were influenced by the hydration state of the toad. Fully hydrated and slightly dehydrated animals travelled farthest at high test temperatures, whereas more dehydrated animals moved farthest at intermediate temperatures. Body temperature and hydration state showed statistically significant interaction and individual toads varied in their tolerance of those parameters. Thus, the relative performance capacities of individual toads under natural conditions cannot be predicted from laboratory measurements at a single combination of body temperature and hydration.
Department, Program, or Center
Thomas H. Gosnell School of Life Sciences (COS)
Functional Ecology 3N6 (1989) 693-699
RIT – Main Campus