WINDEL, N.*; ZORRILLA, S.; Univ. of the Ozarks; Univ. of the Ozarks: Air temperature can entrain circadian activity in armadillos
Many diverse animal species exhibit behaviors that cycle over the period of one day, or in a circadian rhythm. Most animals have an internal clock that is sufficient for maintaining a regular schedule of activities, but use the daily cycle of light and darkness to synchronize their internal clocks with the daily cycles of the external environment. However, the armadillo (Dasypus novemcinctus), spends most of the day in dark burrows where changes in sunlight may not be detectable. The purpose of this experiment is to determine whether daily cycles in air temperature can entrain daily activity patterns in armadillos. Patterns of circadian activity were observed hourly over two weeks in six, laboratory-housed, armadillos. During the first week of the experiment, the control or free-running period, temperature (23oC), light (on), humidity, and hourly disturbance by observers were kept relatively constant, without any daily variation. During the second week, the treatment or entraining period, all factors remained the same except that the air temperature fluctuated from ca. 20oC (0400-1500 hrs) to ca. 26oC (1500-0400hrs), out of phase with what might naturally occur outdoors. During the control period armadillo activity levels were not statistically different between (0400-1500 hr.) and (1500-0400 hr.). During the treatment period, armadillos were statistically more active during the cool period (0400-1500) than during the warm period (1500-0400). We conclude that armadillos can use daily cycles in temperature to set their biological clocks.
