The Long-eared Owl inhabits open and sparsely forested habitats across North America and Eurasia between 30° and 65°N latitude. Isolated populations also occur in North and East Africa, the Azores, and the Canary Islands. Although the biology of this owl has been studied extensively in the United States and Europe, little is known about it in other parts of its range. Most studies have focused on food habits and nesting biology.
The Long-eared Owl typically nests in trees, laying its eggs in abandoned stick nests of other species. Less often it nests in cavities in trees or cliffs, or on the ground. Although it prefers to nest and roost in dense vegetation, it hunts almost exclusively in open habitats. With long wings and light wing-loading, the Long-eared Owl is an active-search hunter, taking a variety of small rodents. It normally hunts at night and probably locates most of its prey by ear.
This species often roosts communally during the nonbreeding season; typical roosts contain 2 to 20 birds, but up to 100 have been reported. In northern Europe, Long-eared Owl numbers fluctuate with those of the species' principal prey, Microtus voles. This relationship has not been well-documented in North America, perhaps because studies here have focused on areas where Microtus are not the principal prey. Although this owl winters throughout most of its breeding range, some individuals migrate long distances, with several records of birds banded in the northern United States and southern Canada and recovered in Mexico.
Long-eared Owl populations appear to be stable in most of North America, but in some places this species has declined because of destruction of riparian vegetation, conversion of hunting areas to agricultural fields, and reforestation of open areas.
Throughout this account, measures of variation about the mean are indicated as ±1 SD.