The white swan (Cygnus olor) is considered partially migratory as the populations of Nordic countries can migrate in autumn while the species is mostly 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.