Ecological energetics of the European mole (Talpa europaea)
European moles (Talpa europaea) were brought from the wild and maintained in captivity where they were fed on lean ox heart with a vitamin and mineral supplement. The mean resting metabolic rate (RMR) of moles around thermoneutral (25oC) was 0.54 Watts, higher (112% ) than the prediction from body mass for mammals generally or fossorial mammals(106% ). Moles showed no clear thermoneutral zone and RMR continued to decline to 0.346 Watts at 30oC. The fitted curve of RMR with temperature gave an estimate of mean minimal thermal conductance of 0.0387 Watts.oC-1. The body temperature of the mole started to rise at 26-30oC, and upper lethal ambient temperature was 35-37oC, indicating low thermal conductance (TC) and a limited ability to alter TC at high ambient temperatures. This is possibly a reflection of the cool, stable thermal environment in which the mole lives. Digging metabolic rate (DMR) was 2.3xRMR at 25oC, similar to the DMR measured in other talpids. The net cost of digging was 1.5xBMR and was independent of ambient temperature, indicating that no thermal compensation occurred. Body mass had a significant effect on DMR but no effect on RMR. Mean deep body temperature measured using temperature telemetry averaged 36oC in two moles and 38oC in the third mole. Body temperature increased slightly with ambient temperatures of 10-25oC and rapidly at temperatures above 25oC. Body temperature did not rise significantly during continuous digging in soil at 5-15oC. There was no evidence of a reduction in resting body temperature in a mole with restricted food intake and at low ambient temperature. Earthworms (Lumbricus terrestris) contained 75% water and had an energy content of 11.21kJ.g-1 dry mass. Ox heart had a mean water content of 79% and energy content of 22.56kJ.g-1 dry mass. The apparent dry mass absorption efficiencies by moles of earthworms and ox heart were 62% and 88% respectively. Apparent energy absorption efficiency was 77% and 93% respectively.