Thermoregulatory responses of the North American porcupine (Erethizon dorsatum bruneri) to decreasing ambient temperature and increasing wind speed.

Average resting metabolic rate of five adult male porcupines (Erethizon dorsatum bruneri) was 0.23 ml O2/g.h +/- 0.007 SEM, between 10 degrees C (Tlc) and 25 degrees C, which is 70% of the value predicted by body mass. A Tb of 37.1 degrees C +/- 0.1 SEM was maintained between -10 degrees C and 25 degrees C. Calculated thermal conductance (between 6 degrees C and -10 degrees C) was 87% of the predicted value. There was no significant change in mean metabolic rate as a function of wind (up 4.3 m/s) at ambient temperatures (1 degree C and -5 degrees C) below their Tlc. Under these same ambient conditions, with and without wind, the skin surface and subcutaneous areas of the porcupine's rosette region exhibited marked temperature lability.