Since prehistoric times humans have used furs for clothing. Traditionally, the prized furs have been sable, marten, and fisher (all of the genus Martes ), the related mink and ermine (of the genus Mustela ), and the chinchilla, from South America. The coats of the ocelot, the wildcat, the common house cat, the marmot, the nutria, the raccoon, the hare, and the rabbit are less expensive because the animals are numerous and easy to trap. Beaver and seal are prized for their durability, but such furs as squirrel and skunk are valued for their delicacy of texture. Fox furs have also been much esteemed, and the rare wild silver fox and Pribilof blue fox are sought after, although silver fox is now bred on fur farms.