The white swan (Cygnus olor) is considered partially migratory because the populations of Nordic countries can migrate in autumn while most of the species is sedentary. These territorial birds can become aggressive when an intruder enters their territory like foxes, wolves, and coyotes, their main predators. The white swan's lifespan extends from 15 to 20 years in the wild. It is a monogamous bird that only has one mate during its lifetime.