Saturday 24th February 2018
Species Guide
Tawny Owl - Strix aluco

The Tawny Owl has a distribution stretching discontinuously across temperate Eurasia from Great Britain and the Iberian Peninsula eastwards to western Siberia, and India. This essentially non-migratory owl is absent from Ireland. This species is found in deciduous and mixed forests, and sometimes mature conifer plantations, preferring locations with access to water. Cemeteries, gardens and parks have allowed it to spread into urban areas, including central London.

This species has expanded its range in Belgium, the Netherlands, Norway and Ukraine, and populations are stable or increasing in most European countries. It has been reported, sadly, in Finland, Estonia, Italy and Albania that the Tawny Owl has shown signs of decline.

The Tawny Owl's main diet consists of small mammals and rodents, small birds, frogs, fish, insects and worms. The Tawny Owl hunts almost entirely at night, watching from a perch before dropping or gliding silently down to its victim, but very occasionally it will hunt in daylight when it has young to feed. Prey is typically swallowed whole, with indigestible parts regurgitated as pellets. These are medium-sized and grey, consisting mainly of rodent fur and often with bones protruding, and are found in groups under trees used for roosting or nesting.

Less powerful woodland Owls such as the Little Owl and the Long-eared Owl cannot usually co-exist with the stronger Tawny, which may take them as food items, and are found in different habitats; in Ireland the absence of the Tawny allowed the Long-eared to become the dominant owl. Similarly, where the Tawny Owl has moved into built-up areas, it tends to displace Barn Owls from their traditional nesting sites in buildings.

Tawny Owls pair off from the age of one year, and stay together in a usually monogamous relationship for life. An established pair's territory is defended year-round and maintained with little, if any, boundary change from year to year. The pair sit in cover on a branch close to a tree trunk during the day, and usually roost separately from July to October. Roosting Owls may be discovered and "mobbed" by small birds during the day, but they normally ignore the disturbance. The Tawny Owl typically nests in a hole in a tree. The typical clutch of two or three eggs is incubated by the female alone for 30 days to hatching, and the altricial, downy chicks fledge in a further 3539 days. The young usually leave the nest up to ten days before fledging, and hide on nearby branches.

The parents care for young birds for two or three months after they fledge, but from August to November the juveniles disperse to find a territory of their own to occupy. If they fail to find a vacant territory, they usually starve. The juvenile survival rate is unknown, but the annual survival rate for adults is 76.8%. The typical lifespan is five years, but an age of over 18 years has been recorded for a wild Tawny Owl, and of over 27 years for a captive bird.

This species is fearless in defence of its nest and young, and, like other Owls in the Strix genus, the Tawny strikes for the intruder's head with its sharp talons. Because its flight is silent, it may not be detected until it is too late to avoid the danger. Dogs, cats and humans may be assaulted, sometimes without provocation. Perhaps the best-known victim of the Tawny Owl's fierce attack was the renowned bird photographer Eric Hosking, who lost his left eye when struck by a bird he was attempting to photograph near its nest. He later called his autobiography An Eye for a Bird.

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