The Head The head of a bird of prey contains its senses for locating its prey and its equipment to eat it.

The Raptor Trust is against the keeping of any bird of prey as a pet, but especially so with owls which seem to have a popularity which leads people to take them on, little knowing or appreciating the skills and commitment required to do so properly. This popularity is no doubt due in large degree to the fact that owls look nice: like us they have forward-facing eyes, blink the same way we do over huge, appealing brown eyes, and they are soft to the touch. Not very well-considered reasons for keeping one of Nature's most ruthless and efficient predators.

Owls are predominantly nocturnal hunters though not by any means exclusively, with some species strictly diurnal and some nocturnal species hunting from time to time during daylight hours (when they have a nest full of young, for instance). They all, however, have the same basic attributes.

Eyes
The colouration of the iris will generally give a clue as to the times when an owl is active - daytime hunters such as the Snowy, Little and Short-Eared owls are mainly yellow-eyed and diurnal, with the brown-eyed Tawny and Barn owls mainly nocturnal. The orange-eyed Long-Eared owl is happy to hunt by day or night, though prefers night.

One very popular misconception regarding owls is that they can see in total darkness. This is not the case - if there is no light then owls are as blind as you or I. However, there is rarely if ever a night without any form of light and what an owl can do is see in light levels so low that any human would be effectively blind. Light is measured in lux and even on the darkest night there is always some form of light which will enable the owl to see. The lowest number of lux in which humans can see is 37,000 whereas experiments on a Tawny owl revealed that the lowest level at which it was able to see was 7 lux! Nigh on total darkness and reaching theoretical limits. Another experiment involved a Barn owl put into a room which was pitch black. A dead mouse was put in with it, but the owl never knew it was there.

The shape of the eye has been developed to make the best use of available light and has resulted in the rear of the eyeball going to something of a point so the overall shape of the eyeball is more conical than spherical. This, coupled with the huge size of the eye (and remember that what you can see of it is only about a third of what is there) has resulted in the fact that owls' eyes are fixed in their sockets - they cannot move them at all. A further disadvantage of the shape of the eyeball is the fact that it gives the owl an astigmatism which means that anything within a foot or so is just a blur and it needs to feel for its food with its crines (see below).

In common with diurnal birds of prey, owls have a third, protective, eyelid (or nictating membrane) but they differ inasmuch as both upper and lower eyelid move when the owl blinks or closes its eyes.

Unlike diurnal raptors which have good peripheral vision, owls are similar to us in relying almost exclusively on their binocular vision, having very little peripheral sight.

Beak
As previously stated, owls can operate in almost totally dark conditions using binocular vision. Therefore, anything protruding in front of the eyes will present something of a barrier to their light-gathering abilities and so reduce their effectiveness. So what does the owl do? It points its beak downwards, out of its line of sight.

At the top of the beak is the cere which houses the nostrils. Although owls, in common with diurnal raptors other than Turkey Vultures, are not believed to have much by way of a sense of smell, an experiment was done with a Tawny owl which happily ate 'good' pieces of liver but reportedly refused liver which had gone off. Opinion seems to be divided on the subject.

While the feet generally dispatch an owl's prey, they are capable of killing it by a nip to the back of the skull with the beak