Eurasian eagle-owl
Even those near the northern limits of their range, where winters are harsh and likely to bear little in food, the eagle-owl does not leave its native range. There are cases from Russia of Eurasian eagle-owls moving south for the winter, as the icebound, infamously harsh climate there is too severe even for these hardy birds and their prey. Similarly, Eurasian eagle-owls living in the Tibetan highlands and Himalayas may in some cases vacate their normal territories when winter hits and move south. Even in those two examples, there is no evidence of consistent, annual migration by Eurasian eagle-owls and the birds may eke out a living on their normal territories even in the sparsest times.
Eurasian eagle-owl
Conversely to numerous threats and declines incurred by Eurasian eagle-owls, areas where human-dependent non-native prey species such as brown rats ("Rattus norvegicus") and rock pigeons ("Columba livia") have flourished, have given the eagle-owls a primary food source and allowed them occupy regions where they were once marginalized or absent.