Description: The long-tailed weasel is a medium-sized, long-bodied member of the genus. It can be distinguished by: 1) short legs, 2) relatively long tail about half its total length, the terminal quarter being black, 3) brown summer fur on the back, outer surface of the legs and basal portion of the tail, 4) throat, belly, and insides of the legs ochre, buffy, or yellowish-white, 5) white winter coat except for the black tail tip (some individuals may have white and brown mottled winter coats while many retain brown winter coats), and 6) brown face, marked in weasels from southwestern Kansas by white blazes on the snout and cheeks ("bridled" weasel). Males are much larger than females.
Size: Adults may attain the following dimensions: total length 343-459 mm; tail 110-175 mm; hind foot 39-54 mm; ear 12-27 mm; weight 130-316 grams.
Range and Habitat: Long-tailed weasels are distributed throughout the state. They are often found in open grassland, shrubby areas, along woodland borders, and riparian forests. They are most abundant near creeks, rivers, lakes, and forests. Long-tailed weasels tend to avoid open woodland and extremely arid conditions.
There are three subspecies of the long-tailed weasel in Kansas; Mustela frenata longicauda Bonaparte in the western third of the state north of Edwards county (circles), Mustela frenata neomexicana (Barber and Cockerell) in the southwest corner of the state (squares), and Mustela frenata primulina Jackson in the eastern two-thirds of the state (triangles).
Reproduction: The long-tailed weasel breeds in July and August. Fertilized ova develop for approximately eight days, then cease development for about seven and one half months. After this time the embryos resume development, and four to nine (usually six to eight) young are born 27 days later. The gestation period may cover 205 to 337 (average 279) days. The newborn young are blind, unfurred, about 65 mm long, and weigh three grams. They soon develop a soft, white fur which is replaced in three weeks by adult fur. By the fourth week their teeth have erupted. Their eyes open by five weeks of age at which point weaning begins. During weaning the male may help provide the young with food. By 50 to 60 days the difference in size of the sexes is evident. Later the young accompany the female while she hunts, and disperse when they are 70 to 83 days old. Female long-tailed weasels may breed at three to four months of age while males are not sexually mature until the year following their birth.
Habits: Long-tailed weasels are both diurnal and nocturnal, but are reported to be more active after sundown and before sunrise. Home ranges vary in size, depending upon the locality, time of year, and abundance of food. Home ranges increase in size as food becomes less abundant, and are larger in open forests. They may cover three to 90 hectares, but usually average nine to 12 hectares. Ranges between animals frequently overlap, and individuals may cover their entire range in a single night. Males usually move farther than females. Males may average 230 meters per night and females 105 meters per night. Population densities may vary from one to 32 long-tailed weasels per square kilometer.
Long-tailed weasels confine most of their activities to the ground. However, they will climb trees pursuing prey, and, sometimes to escape predators. They rarely enter water. Dens are constructed at the bases of trees, stumps, or rocks. Chipmunk ground squirrel, gopher, or mole burrows may be modified and used as dens. The burrow is usually 0.7 to 0.9 meters long and 150 to 430 mm; below the surface. The nest chambers are approximately 0.3 meters in diameter. Shredded grasses and leaves may be gathered for bedding although some nests contain little if any bedding.
Food: Long-tailed weasels are highly carnivorous. Well over half the diet consists of small mammals; voles, deer mice, pocket gophers, ground squirrels, house mice and rats. Tree squirrels and rabbits are less frequently eaten. Ground nesting birds and insects are eaten when preferred food is scarce and berries may be consumed when ripe.
Remarks: Long-tailed weasels do not appear to be abundant anywhere in Kansas. Wherever they occur they are major predators of small mammals. Bobcats, foxes, coyotes, eagles, hawks, and owls are reported to prey on long-tailed weasels. Maximum longevity of this mammal is three to four years in the wild, and up to five years in captivity.
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