Reproduction, postnatal development and resting metabolic rate of a poorly studied subterranean rodent, the long-clawed vole ( Prometheomys schaposchnikowi )

The long-clawed vole (LCV) is a poorly studied species endemic to the Caucasus Mountains. It is a rare example of a small subterranean rodent living in a cold climate. Subterranean lifestyle and low ambient temperatures are thought to affect an animal’s “pace-of-life” in opposite directions, and it is currently unknown how LCV solve this trade-off. We report key aspects of reproduction and postnatal development as well as resting metabolic rate (RMR) and low critical temperature ( T lc ) in captive LCV. Mean litter size was 2.9 (± 0.9 SD, range 1–4) and gestation lasted 32–33 days. The embryonic and pre-weaning postnatal growth rate was low when adult weight of 80–90 g was taken into account (0.14 g/day and 0.8 g/day, respectively). Juveniles developed very slowly (eyes opening at 22–25 days) and weaned at about 1 month. Members of breeding pairs exhibited permanent nest cohabitation. Males were present at birth and displayed paternal care of pups. Females may become pregnant by 50 days or even earlier. The T lc was estimated as 18.9 (± 0.9 SE) °C. The mass-independent basal metabolic rate (BMR) was 1.65 (± 0.08 SD) mL O 2 /g × h, which is close to the expected value calculated from the allometric relationship between body mass and BMR determined for other voles adapted to similar climate conditions. The unusual combination of several slow life history traits with relatively early sexual maturation and unreduced BMR apparently constitute elements of the unique adaptive complex of the relatively small, strictly herbivore subterranean rodent living in cold humid habitats.