Ominous Owls: Sharp-eyed Hunters of the Night

In size, owls range from intimidating eagle-owls, with wingspans of almost two metres, capable of taking down peafowl and mouse deer, to the tiny elf-owl, hardly bigger than a sparrow and tipping the scales at a dainty 31 grams.

Most owls are cryptically coloured to merge with their surroundings: stippled and dappled in greys, browns, and buffs. Their eyes, usually with golden-yellow or burning orange irises, are colossal given the size of the head. They are forward-facing and give the bird binocular vision and enable it to sense depth. They are tubular shaped to fit in the skull, which means the bird cannot move them from side to side or roll them as we do. It has to swivel its whole head to change its viewpoint and can do so without moving a muscle in the rest of its body. You may have experienced owls bobbing their heads from side to side as they glare at you: they’re trying to get a fix on your position and figure you out! And thanks to special nerve and blood vessel adaptations in their necks, they can do the 270-degree swivel without cutting off the blood supply to their brain or passing out. Owls can see very well long-distance in the dark, but at very short ranges — when the prey is actually in their talons, for example — they fall woefully short. On their beak and talons, special feathers called filoplumes work as feelers to tell them exactly where their prey is.

Rats and other rodents often stay underground in burrows or under foliage and hay and are invisible. The owl brings into play its exceptional sense of hearing. For a start, its circular facial disc (often with a surrounding movable ruff of feathers) funnels sound towards its ears, rather like a satellite dish. Its ears are acutely sharp and asymmetrically positioned. They catch the faintest rustle of a rat moving around in its burrow or under foliage. Being asymmetrical means each ear receives the sound at a fraction of a second (30 microseconds) sooner or later than the other. By swivelling its head so that both sounds merge into one, the owl pinpoints its victim’s exact location in pitch darkness.

Owl wings are designed for slow, deliberate flight. Velvety plumage and wing feathers are specially muffled, downy and serrated, damping down any sound they might make while beating. Whatever sound emerges is usually below the hearing range of both the prey and owl itself, so not only is the prey unaware of the impending attack, but the owl is undisturbed by the sound of its own wing-beats.

Many years ago, at a raptor rescue centre in California, I watched a quartet of barn owls fly towards me in their huge aviary and was astounded and a little unnerved. It was like watching a silent film — the ghostly birds flew closer and closer until they were perhaps six or eight feet away, and I didn’t hear a single wing-beat. But there’s a downside to this: the adaptations for soundproofing mean that owl feathers are not waterproof, nor do owls have a preen gland or powder down to groom themselves. Worse, they can’t hunt when it rains, which can prove fatal for a family. Many a barn owl has drowned in livestock water-troughs where they came to drink. In the absence of waterproofing, to stay warm, owls have a large number of down feathers that retain body heat.

The talons and hook-tipped beak are knife-keen and perfectly adept for their function: to grip, rip, and tear flesh. The down-curved bill ensures clear forward vision and directs sound towards the ears.

Their calls may vary from the deep echoing hoots of great eagle-owls to the blood-curling shrieks and screeches of barn owls via the querulous chittering of little owlets.

Owls usually nest in holes or hollows in trees, though the larger ones reside in huge twiggy edifices in the canopy, which in some species become ancestral homes. Eggs are usually round and white and may number from a singleton to a dozen. The mothers tend to favour stronger chicks, especially when food is scarce.

Females are often larger than their partners, and there are several theories for this. One is that the male is usually the hunter, and being more compact may be advantageous. Another is that since females are ferocious and may kill a male they do not like: being smaller enables a quicker getaway for the rejected gentleman. Yet another theory is that the lady usually remains on the nest while incubating and bringing up the brood, and being bigger may help her tide over long periods without food. Owls are fierce defenders of their personal space as the photographer, the late Eric Hosking, found to his cost, losing an eye to the talons of a tawny owl he got too close to back in 1937.

Humans have had a bipolar relationship with owls. From veneration as founts of wisdom in parts of the west (Athena, goddess of wisdom, had an owl as her symbol) to harbingers of death (in Africa, South and Central America, and Europe — where owls were said to have foretold the death of Julius Caesar). In India (always complicated!), owls were considered as the “vahan” (vehicle) of goddess Lakshmi and all her accompanying wealth, prosperity and ill omens — presaging evil times and oncoming death. Worse, so-called “black magic” practitioners kill them and use their body parts for gory rituals (Diwali is a terrible time for owls in India), endangering some species. Owls also fall prey to poachers and poisoned rodents — when, in fact, they ought to be lauded for their contribution towards rodent control. Some enlightened farmers do encourage owls on their property for this reason. These silent night hunters deserve all the admiration and accolades we can bestow upon them.