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Tawny Owl

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The Tawny Owl (Strix aluco), is an owl the size of a pigeon. It has a rounded body and head, with a ring of dark feathers around its face surrounding the dark eyes. It is mainly reddish brown above and paler underneath. It is a widespread breeding species in England, Wales and Scotland but not found in Ireland. Birds are mainly residents with established pairs probably never leaving their territories. Young birds disperse from breeding grounds in autumn.

TAWNY OWL

Tawny Owl - CNI

Where To See Them

The tawny owl is almost entirely nocturnal so it is often heard calling at night, but much less often seen. (If you hear a 'tawny owl' calling in daylight, it may be a jay , which sometimes mimics birds of prey). In the daytime, you may see one if you disturb it inadvertently from its roost site in woodland up against a tree trunk or among ivy - or occasionally you may come across an owl feeding on carrion in daylight. Look for pellets below roosting places. Tawny owls can be seen at any time of the year.


What They Eat

Small mammals and rodents, small birds, frogs, fish, insects and worms.


DescriptionEdit

The Tawny Owl is a robust bird, 37–43 cm (14.5–17 in) in length, with an 81–96 cm (32–38 in) wingspan. Its large rounded head lacks ear tufts, and the facial disc surrounding the dark brown eyes is usually rather plain. The nominate race has two morphs which differ in their plumage colour, one form having rufous brown upperparts and the other greyish brown, although intermediates also occur. The underparts of both morphs are whitish and streaked with brown. This species is sexually dimorphic; the female is much larger than the male, 5% longer and more than 25% heavier.

The Tawny Owl flies with long glides on rounded wings, less undulating and with fewer wingbeats than other Eurasian owls, and typically at a greater height.The flight of the Tawny Owl is rather heavy and slow, particularly at its first entering on the wing. As with most owls, its flight is silent because of its feathers' soft, furry upper surfaces and a fringe on the leading edge of the outer primaries. Its size, squat shape and broad wings distinguish it from other owls found within its range; Great Grey, Eagle and Ural Owls are similar in shape, but much larger.

An owl's eyes are placed at the front of the head and have a field overlap of 50–70%, giving it better binocular vision than diurnal birds of prey (overlap 30–50%). The Tawny Owl's retina has about 56,000 light-sensitive rod cells per square millimetre (36 million per square inch); although earlier claims that it could see in the infrared part of the spectrum have been dismissed, it is still often said to have eyesight 10 to 100 times better than humans in low-light conditions. However, the experimental basis for this claim is probably inaccurate by at least a factor of 10. The owl's actual visual acuity is only slightly greater than that of man, and any increased sensitivity is due to optical factors rather than to greater retinal sensitivity; both humans and owl have reached the limit of resolution for the retinas of terrestrial vertebrates.

Adaptations to night vision include the large size of the eye, its tubular shape, large numbers of closely packed retinal rods, and an absence of cone cells, since rod cells have superior light sensitivity. There are few coloured oil drops, which would reduce the light intensity. Unlike diurnal birds of prey, owls normally have only one fovea, and that is poorly developed except in daytime hunters like the Short-eared Owl.

Hearing is important for a nocturnal bird of prey, and as with other owls, the Tawny's two ear openings differ in structure and are asymmetrically placed to improve directional hearing. A passage through the skull links the eardrums, and small differences in the time of arrival of a sound at each ear enables its source to be pinpointed. The left ear opening is higher on the head than the larger right ear and tilts downward, improving sensitivity to sounds from below. Both ear openings are hidden under the facial disk feathers, which are structurally specialized to be transparent to sound, and are supported by a movable fold of skin (the pre-aural flap).

The internal structure of the ear, which has large numbers of auditory neurons, gives an improved ability to detect low-frequency sounds at a distance, which could include rustling made by prey moving in vegetation. The Tawny Owl's hearing is ten times better than a human's, and it can hunt using this sense alone in the dark of a woodland on an overcast night, but the patter of raindrops makes it difficult to detect faint sounds, and prolonged wet weather can lead to starvation if the owl cannot hunt effectively.

The commonly heard contact call is a shrill, kew-wick but the male has a quavering advertising song hoo...ho, ho, hoo-hoo-hoo-hoo. William Shakespeare used this owl's song in Love's Labour's Lost (Act 5, Scene 2) as "Then nightly sings the staring owl, Tu-whit; Tu-who, a merry note, While greasy Joan doth keel the pot", but this stereotypical call is actually a duet, with the female making the kew-wick sound, and the male responding hooo. The call is easily imitated by blowing into cupped hands through slightly parted thumbs, and a study in Cambridgeshire found that this mimicry produced a response from the owl within 30 minutes in 94% of trials. A male’s response to a broadcast song appears to be indicative of his health and vigour; owls with higher blood parasite loads use fewer high frequencies and a more limited range of frequencies in their responses to an apparent intruder.

GalleryEdit

VideosEdit

Tawny Owl01:24

Tawny Owl

Tawny Owl - C.N.Images

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