The barn owl feeds on small rodents, especially voles and mice (11), and on frogs and insects (2), which it locates using its excellent sense of hearing (9). It is usually active in the evening, early morning or at night (11), but in times of hard frost or snowfall, individuals may be forced to hunt for longer periods, and may be seen in the day (6). The unlined nest is made in hollow trees or in old buildings. In April or May, between 4 and 6 white eggs are laid. These are incubated solely by the female, who is fed by the male during this time (5). Incubation starts after the first egg is laid, so they hatch at intervals (11), 32-34 days after being laid (5). The young therefore vary widely in age and size (11), and spend a very long time in the nest, between 64-86 days (5).