Seasonal acclimatization in the migratory hamster Cricetulus migratorius-the role of photoperiod

1. 1.|The migratroy hamster Cricetulus migratorius, a small nocturnal rodent, inhabits ecosystems characterized by dramatic seasonal fluctuations of ambient temperatures. The aim of this study was to assess seasonal acclimatization of its thermoregulatory system. 2. 2.|Heat production by means of oxygen consumption and body temperature in various ambient temperatures as well as non-shivering thermogenesis were measured in C. migratorius. The hamsters were acclimated to two different photoperiod regimes (16L:8D and 8L:16D) at a constant ambient temprature of 24°C. Overall thermal conductance was calculated for such hamsters. 3. 3.|The results of this study indicate that photoperiod manipulations adjust the thermoregulatory system of the migratory hamster mainly by affecting overall thermal conductance.