The weasel family is distributed worldwide (except Australia, New Guinea, Madagascar and Antarctica) and includes 67 species. Six of these small carnivores live in Switzerland. The otter, however, was exterminated. These animals are physiologically well adapted to hunt their prey which consists mainly of small rodents. The typically long, slender and sinewy body allows most mustelids to pursue prey species right to their tunnels and dens, for example. With extraordinarily keen senses and extreme agility these relatively small carnivores live as solitary hunters. Their highly developd and sensitive whiskers are used for such purposes. They communicate with each other through glandular secretions used in marking behaviours. Most mustelid species use the particular system of delayed implantation to regulate reproduction.