Sunday, 20 February 2011

Barn Owl

Barn Owls do exactly what it says on the tin. They have evolved to be silent hunters and they do it with graceful efficiency. They possess, of course, impressive talons: four toes, three of which face forward when the bird is in flight and the uniquely flexible outer front toe on each foot can swivel round to face backwards when the bird is at rest. The bone structure in the Barn Owl's feet are also shorter and stronger than the equivalent bones in most other birds, giving this consummate hunter an advantage – these high-stress limbs can withstand the considerable relative force of an impact with its prey. But in these images, I've concentrated on body feathers and the organs that provide the owl with super-senses – its eyes and the ears. Compared to most birds, Barn Owls have a very low wing loading, meaning that relatively large wings support a relatively small body mass. Its feathers are very soft, another adaptation for quiet flight, and they are covered in a discreet layer of tiny hairs that trap air within the feather surface. In addition to these adaptations, the Barn Owl's foremost wing feather (the 10th primary) has a row of tiny hooks that help to deaden the sound of air hitting the wings' leading edge. Together, these adaptations mean almost silent flight is possible, allowing ambush by stealth twinned with the ability to detect the small sounds produced by their small mammal prey. In January, I found a dead, ringed Barn Owl on the farm on which I live and – once I had passed on details of the release data to the BTO – I took the opportunity to examine its unique auditory set-up. The owl's heart-shaped face – the equivalent of our outer ear – acts like a huge radar, picking up and directing even the most delicate sounds into the inner ear. And those inner ears – hidden beneath its head feathers and each of them different in shape and sited asymmetrically with one higher than the other – mean the bird can further compute the signals received to finesse its hunting plan. Then there are the eyes. Huge in comparison to the size of the head and twice as sensitive to light as our own eyes, the owl can hunt for prey in near darkness and, with details in what we would see as shadows, the bird can detect even the slightest movement in the blackness. A most beautiful killer…

Source: The Barn Owl Trust ( www.barnowltrust.org.uk )

Canon 1Ds MkII, 1/640 sec, f/4, 180mm at ISO 500













1 comment:

  1. FABulous images Tim of the silent hunter's face.

    ReplyDelete