Weasels belong to the Mustelidae family, which also includes mink, martens, fishers, wolverines, badgers, river otters, black footed ferrets and four species of skunks. Although members of the weasel family vary in size and color, they usually have long, slender bodies, short legs, rounded ears, and anal scent glands. A weasels hind legs are barely more than half as long as its body. The weasels forelegs are also notable short. Male weasels are distinctly larger than females. 

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General Biology, Reproduction and Behavior

Weasels are active in both winter and summer; they do not hibernate. Weasels are commonly thought to be nocturnal but evidence indicates they are more diurnal in summer than in winter. 

Home range sizes vary with habitat, population density, season, sex, food availability, and species. The lease weasel has the smallest home range. Males use 17 to 37 acres, females 3 to 10 acres. The short tailed weasel is larger than the least weasel and has a larger home range. Male short tailed weasels use an average of 84 acres and females 18 acres. 

The long tailed weasel has a home range of 30 to 40 acres and males have larger home ranges in summer than do females. The weasels appear to prefer hunting certain coverts with noticeable regularity but rarely cruise the same area on two consecutive nights. 

Weasel population densities vary with season, food availability, and species. Weasels, like all mustelids’, produce a pungent odor. When irritated, they discharge the odor, which can be detected at some distance. 

Long tailed weasels mate in late summer, mostly from July through August. Females are induced ovulators and will remain in heat for several weeks if they are not bred. They is a long delay in the implantation of the blastocyst in the uterus, and the young are born the following spring, after gestation period averaging 280 days. Average litters consist of 6 young, but litters may include up to 9 young. The young are blind at birth and their eyes open in about 5 weeks. They mature rapidly and at 3 months of age the females are fully grown. Young females may become sexually mature in the summer of their birth year. 

Damage and Damage Identification

Occasionally weasels raid poultry houses at night and kill or injure domestic fowl. They feed on the warm blood of victims bitten in the head or neck. Rat predation on poultry usually differs in that portions of the body may be eaten and carcasses dragged into holes or concealed locations. 

Information is from Prevention and Control of Wildlife Damage-Cooperative Extension University of Nebraska-Great Plains Agricultural Council Wildlife Committee-United States Department of Agriculture Animal and Plant Health Inspection Service Animal Damage Control