Erthyrocyte changes in the hibernating woodchuck (Marmota monax)

Active woodchucks were maintained at 23 °C with a photoperiod of LD 12:12. Hibernating woodchucks were kept at 10 °C with a photoperiod of LD 8:16. Blood was collected and the erythrocytes were counted and measured.The data showed an increase in red blood cell count, a decrease in erythrocyte diameter and a decrease in mean corpuscular diameter during hibernation. The hematocrit was the same in both the hibernating and active woodchucks. It would appear that there are a greater number of smaller cells present in the circulation of the hibernating woodchuck as compared to that of the active woodchuck. This may result from the combined effects of increased life span, decreased destruction and continued, but slowed, production of red blood cells.