Tawny Owl

A Hunter That Finds Prey By Ear

A tawny owl hunts mostly between dusk and dawn, and for a night hunter, hearing is crucial. Its eyes sit at the front of its head with a 50 to 70 percent overlap between their fields, which gives it more binocular vision than birds that hunt by day. Its two ear openings are built differently and set asymmetrically on the head, and the left one tilts downward to catch sounds from below. The owl locates a sound from the tiny difference in when it reaches each ear. It perches and watches, then glides down silently to catch its prey on the ground, covering it with its wings and killing it with its feet and claws. Rain is its weak spot: the noise of rainfall easily interferes with its hearing, and prolonged rain can leave it unable to hunt and starving.

Built Like a Woodpigeon

A tawny owl is about the size of a woodpigeon: a rounded body and head with no ear tufts, and a ring of dark feathers around its face surrounding its dark eyes. It averages 38 centimeters long with a 99-centimeter wingspan. Live adults weighed by British ringers average about 396 grams for males and 502 grams for females. British ringing records put a tawny owl’s typical life expectancy at 4 years once it reaches breeding age, and the oldest ringed bird lived 23 years, 5 months and 27 days, a record set in 2016. Its range runs across the Palearctic, from the Iberian Peninsula east to China and Korea and south to Iran and the Himalayas. It lives in woodland throughout Britain, though not on the Northern Isles, the Outer Hebrides or treeless uplands, and it is absent from Ireland. Its diet is mostly woodland rodents, with other small mammals, amphibians, beetles and worms, and birds make up a bigger share of it in towns and cities.

Two Birds, One Hoot

The familiar “too-whit-too-woo” is made by two birds: the female calls the “too-whit” in answer to the male’s hooting “too-woo.” A pair defends its territory year-round, with minor changes to the boundaries each year, and stakes it out with screeching calls, threats or fights in mid-flight. Territories run from about 0.12 to 1 square kilometer, smaller in dense woodland and larger where prey is scarce.

Talons Aimed at the Eyes A tawny owl defending its nest and young strikes with its talons at an intruder’s head and eyes, and mothers guarding a brood attack even people and domestic animals.

Grey or Brown: A Coat That Comes With Consequences

Tawny owl plumage varies from rufous-brown to greyish-brown, with lighter grey-and-white birds in the northernmost parts of the range. The colour is highly heritable, and a 26-year study of a population in southern Finland found it mattered for more than looks: grey males and females produced more fledglings over their lifetimes than brown owls did, and grey males also produced more young that went on to join the breeding population. The study found that selection worked through survival, not through fecundity, the number of young a bird can produce.