Metabolism and Thermoregulation in Greater Long-Tailed Hamster (Cricetulus triton) From Northern China Farmland

Metabolic rate,body temperature,and thermal conductance of greater long-tailed hamster (Cricetulus triton) from the farmland in Hebei Province were determined at a temperature range of 5-36 ℃.Oxygen consumption was measured by using closed circuit respirometer and temperature was controlled by water bath.The thermal neutral zone was 29-31 ℃.Within the temperature range of 5-31 ℃,hamsters could keep their body temperature stable with mean value at (36.7±0.1)℃.Mean basal metabolic rate within thermal neutrality was (1.23±0.02) mLO2/(g·h).Total thermal conductance was kept stable within the temperature range 5-15 ℃ with mean value at (0.12±0.00)mLO2/(g·h·℃).The properties of the ecophysiology for greater long-tailed hamster were:1)metabolic rate was higher than the predicted value based on the allometric equation of total eutherian mammals,lower than the predicted value of rodent species,and slight higher than the predicted value of cricetid rodents,higher than predicted value of seed-eaters and similar to the predicted value of grazing species;2)the body temperature was relatively low;3)thermal conductance was relatively higher than the predicted value based on their body weight.All these characteristics were close related to their living habits such as nocturnal,mainly feeding on crop seeds and small fraction of young crop leaves and insects,burrowing,and solitary.Greater long-tailed hamster is distributed dominantly in northern Changjiang River in China and they are not likely to survive in extreme dry area and alpine area.Thus,we proposed that ecophysiological characteristics of greater long-tailed hamsters might constrain their distribution and extension to extreme desert or high altitude and cold region.