Tawny Owl
Strix aluco
UK Conservation Status: AMBER
As nocturnal birds, tawny owls are more often heard than seen. They are our commonest owl species.
The territorial hooting call of a male Tawny Owl is probably the most familiar of UK owl calls, beginning with a drawn out ‘hooo’, followed by a brief pause, before a softer ‘hu’ and then a resonant final phrase of ‘huhuhuhooo.’ This final phrase has a strong vibrato quality to it. The female’s usual call is ‘keewik’, which is used as a contact call.
A resident pair will often duet, the male hooting and the female dropping her contact call into the pauses between bouts of hooting. This is what we expect to hear – the so called “twit twoo” sound. Now you know that this sound comes not from one but from two tawny owls!
The BTO provide an excellent set of recordings that help you understand tawny owl calls.
Females typically weigh around 500g, which is roughly the same as a wood pigeon. Males are around 25% smaller. The typical wingspan is up to one metre.
Tawny owls normally pair for life and will defend their shared territory from other owls all year round. After mating, the female lays her eggs in a cavity within a large tree. Old crows' nests, squirrel dreys or special tawny owl nest boxes may also be used.
Typically, two to three eggs are laid in spring, hatching after around a month. The first eggs are usually laid in February, but most pairs do not begin until mid-March or later. Incubation starts with the first egg, leading to asynchronous hatching which gives the first born a permanent advantage – a strategy that is common in owls and which increases the survival of at least some chicks if hunting conditions are difficult.
Before fledging, the fluffy young, known as owlets, will leave the nest and spend several days in the surrounding branches – a process that is called ‘branching’. The owlets can sometimes be found on the ground below the nest site. Unless the chicks are actually under threat of death or injury from a predator, it is best to leave them be. They are surprisingly agile and will just climb back up the trunk of the tree to reach the nest hole.
The parents will continue to care for the young after fledging. Still dependent on their parents for food for up to 3 months after leaving the nest, they will sit around on the branches of nearby trees and beg for food once darkness falls.
Tawny owls feed mostly on small mammals, like mice and voles, but they may also take small birds, amphibians, large insects and earthworms – the latter taken from short-grassland and lawns on damp nights, when the worms are foraging above ground. The owls silently swoop down on their unsuspecting prey. Sensitive sight and hearing allows them to locate rodents, while their wing feathers have a soft furry edge that allows for soundless flight.
Broadleaved woodland is their favoured habitat, but they may venture out into farmland when hunting. Tawny owls can sometimes be found in urban areas provided there is a sufficient number of large trees for roosting and breeding.
The UK’s tawny owl population is estimated to have fallen by more than a third since the 1970s. Exactly why the species is declining is unclear, but a loss of woodland habitat and suitable trees for nesting are likely factors.