Many genera are agile climbers, and otters and minks are skillful swimmers. Mustelids are mainly flesh eaters. They hunt by scent, though the senses of hearing and sight are also well developed. Some species occasionally feed on plant material, a few are omnivorous, and otters subsist mainly on aquatic animals. The storage of food has been reported for Mustela, Poecilogale, Gulo, and certain badgers.
Many mustelids use the secretions of their anal glands as a defensive measure.
This pattern is thought to be a form of warning coloration associated with the fetid anal gland secretion, and a reminder that the animal is better left alone. Delayed implantation of the fertilized eggs in the uterus occurs in many genera. The actual period of developmental gestation is about 30-65 days, but with delayed implantation the total period of pregnancy is as long as 12.5 months in Lutra canadensis. There is usually a single litter per year. The offspring are usually tiny and blind at birth.