Montane vole
Adults typically weigh anything from 37 to 85 grams (1.3 to 3.0 oz), with males being slightly larger than females, but the actual weight varies considerably with age, geography, and subspecies.The tail exhibits the same color variation, with the fur being dark brown to almost black on the upper surface and grey or white below.[8] Montane voles have also been used in the laboratory in studies of African sleeping sickness, since they suffer similar symptoms to humans when infected with the parasite.[16] Females do not have regular estrus cycles,[17] and their reproductive status is apparently induced by chemical signals from nearby males.[19] The young are born blind and helpless, and are not capable of standing until four days after birth, around the time that they first begin to develop fur.