The Short-tailed Weasel, active day or night, may be fairly common at times but is seldom seen. Although it hunts mainly on the ground, often running on fallen logs, it can climb trees and occasionally pursues prey into water. This carnivore kills all that is available and stores the excess. Mice, particularly meadow voles, are its main food, but its diet also includes shrews, baby rabbits, birds, frogs, lizards, snakes, and many kinds of insects. This weasel captures prey several times its own weight, such as a young cottontail. Because of the danger in hunting much larger animals, however, it does so only if an excellent opportunity arises, or in times of scarcity. After a rapid dash, it pounces on its victim with all four feet, biting through the neck near the base of the skull. Weasels lick blood from their quarry before eating it, which is perhaps the source of the myth that they suck blood from prey. The Short-tailed Weasel’s den, which is sometimes appropriated from a chipmunk, may be found in or beneath a log, stump, roots, brush pile, or stone wall. The den usually has several entrances and contains a nest of vegetation mixed with hair and feathers of prey. Rather than curling into a ball the way most animals do, a weasel curls into a disk, thereby exposing more skin surface to the air; the insulation material in the nest compensates for this. Male and female Short-tailed Weasels remain separate most of the year, though male territories encompass those of several females. Territories are expanded when food is scarce. The weasel keeps several nests throughout the territory, using them when it is in the vicinity. The male Short-tailed Weasel does not mature and mate until its second year, but the female is sexually mature in June of her birth year, when spontaneous ovulation begins. Ovulation occurs monthly until the female is bred, often in July. The female remains passive while the male drags her around by the scruff of the neck during copulation. After the female gives birth, her annual estrus begins when her young are about six weeks old. At that time, the male breeds with the female adult and with her female progeny, who may not have their eyes open yet. Most likely, this male is not the newborn females’ father, because Short-tailed Weasels are not monogamous. Cared for by both parents, the young begin to kill prey at 10 to 12 weeks of age. Vocalizations of the Short-tailed Weasel include grunts, hisses, chatters, and a shrill call note. Its predators are hawks, owls, house cats, and other carnivorous mammals and snakes. Although the names "Ermine" and "Stoat" are sometimes used to describe the species in its white winter fur and its brown summer coat, respectively, these names are also given to the Long-tailed Weasel. Ermine was highly valued before the decline of the fur industry, and the black-tipped tails are the traditional trim on the robes of royalty.