The Owl Who Liked Sitting on Caesar (19 page)

One afternoon Mumble was sitting quietly on the long western windowsill on a favoured perch – a large ceramic keg with a solid top. I happened to point my camera at her at exactly the moment when a pigeon must have arrived on the balcony, and so I saw through the viewfinder her transformation, over a period of about five seconds, from fat,
contented owl to thin, suspicious owl. It was as marked as the difference in appearance between, say, a cabbage-shaped lettuce and a cos lettuce; some books say that this response is an automatic attempt by a roosting owl to appear more like a part of the tree trunk it is sitting next to.

First, her head turned towards the intruder, and she fixed her eyes on that bearing with utter intensity. Then, the outline of her body visibly changed: without (on this occasion) extending her legs and standing tall, she compressed her rear shawl feathers so that she grew thinner. Her toque seemed to slip downwards, and a complete change came over her scalp and face. The round ball of her head shrank and altered shape, as the feathers on the back flattened and the frontal crown feathers stood up sharply in a partial ‘Mohican’. The feathers above and between her eyes dropped and stuck forwards horizontally, like bristling eyelashes, and her eyes slitted. Simultaneously, the planes of her facial disc on each side seemed to flatten backwards, giving her a distinctly hatchet-faced look. In those few seconds Mumble’s whole aspect had changed from benign boredom to unmistakably hostile suspicion. She was suddenly an owl on whose wrong side you definitely would not want to get.

* * *

When she was in repose, the feathers on the top and back of Mumble’s head seemed to run back seamlessly, in a single hood, down into the thick shawl of light brown
scapular feathers covering her shoulders and upper back. Except for the outer edges, which were delineated here and there with white feathers barred with dark brown, it was almost impossible to see where each mottled shawl feather met the next, but there was a slight contrast between the whole mass and the darker contour feathers that clothed her lower back.

Birds have many more touch-receptor cells in their skin than mammals, and it is believed that a layer of hair-like
filoplumes
growing beneath the body feathers gather information about pressure and vibration. These pass messages to the brain about the relative positions of the various feathers, and thus enabled Mumble to ‘adjust her clothing’ more or less unthinkingly. Consider this ability in human terms – and be envious. You wake from a nap, and only after you happen to pass a mirror do you realize that you have been walking around with mad hair. If you were an owl, you wouldn’t need a mirror; you would somehow be conscious mentally that your hair was in disarray – and much more acutely conscious of it than your present dim awareness of the pressure of your clothes against your skin. An automatic mental message would pass to muscles in your scalp (admittedly, it would have to be a fairly loose-fitting scalp), and these would shrug your hair back into place and settle it. Who knows, you might even be able to lift a stray forelock out of your eyes without using your hand.

* * *

The whole front of Mumble’s body was covered with thick, fluffy, creamy-white feathers each with a central vertical streak of dark brown. (When she moulted, I could see that in fact only the ends were white and brown – the greater part of each feather was made of loose dark grey filaments, but her plumage was so thick that these were completely hidden from the outside.) These insulating layers were deep and very soft, designed to keep owls warm during long winter hours spent motionless on their roosting branches. Birds have a significantly higher body temperature than we do, and a tawny’s luxurious clothing is a built-in duvet. These fluffy feathers continued down her belly, and back between her legs, becoming plain white in colour where they covered the bottom cone of her body beneath her tail. This cone was an extension of her pelvis, not her vertebrae.

Growing on the separate end of her spinal column, above the cone, were Mumble’s twelve long tail feathers or
retrices
(rudders), their bases reinforced and thatched in above and below by smaller covert feathers. The central four rudders were narrow, of almost constant width, and plain donkey-brown apart from a small off-white tip. On each side of these were four broader feathers, patterned with bars like the flight feathers of her wings. When in sustained flight she spread out all twelve side by side into a broad, rounded fan; as far as I could tell from snatched glimpses, they seemed to be arranged not in a flat plane but in a very shallow arc, with the central four feathers highest and the others slanting away on either side, each overlapping the one below and outside it. When Mumble
was settled she swivelled the patterned outer feathers inwards into a single neatly interlocked stack under the plain central feathers, like the folded vanes of a lady’s fan.

* * *

Owls have very strong legs, with a conventional hip joint at the pelvis and two other major joints (again, a glance at the skeleton drawing on
here
may be helpful). At the bottom end of the thigh or femur, the upper of these two joints – once, the reptilian ‘knee’ – flexes backwards, like our knee, but we hardly ever see this under the body feathers. The lower joint, at the bottom end of the now fused tibia and fibula bones of what was once a shin, flexes forwards. This was once the reptilian ‘ankle’; but below it the reptilian ‘foot’ has elongated enormously, and fused into what we perceive as the owl’s whole lower leg (the tarso-metatarsus). This terminates in what looks to us as if it should be an ankle, but which is actually more akin to the ball of our foot, though with toes extending from it both forwards and backwards.

Most of the time Mumble’s skirts of body feathers and fluff covered her legs down to the second, forwards-flexing joint, and when she settled into her habitual squatting pose the lower legs disappeared too, leaving only her claws showing. She often perched (and slept) standing on one leg only, with the other folded up ‘into her pocket’ among the body feathers. When your instinctive sense of balance is as good as an owl’s, there is no point in exposing both your feet to the winter weather at the same time, and thus
risking them both being cold and stiff if any sudden emergency or opportunity occurs.

Owls have four toes on each foot, and when they are standing or perched at their ease two of these point forwards and two backwards. However, they have a ‘trick’ joint at the base of the outer rear toe that enables them to swing it round towards the front at will, to give a three-forwards/one-backwards grip. They may do this in flight when about to land or to strike at prey. Mumble’s whole legs and the upper surface of her feet were covered with a fur of fine, pale, buff-grey feathers, to keep them warm and to offer slight protection against the nipping teeth of any defiant prey. On the rare occasions when her whole legs were exposed I noticed that the feathers were thicker around her lower legs and feet than her upper legs, giving the impression that she was wearing fur boots laced tight at the top and flaring out over the instep below. Among these foot feathers, sensitive
filoplumes
gave her nervous system a degree of feedback about anything they touched.

The bottoms of Mumble’s toes showed pale pinkish-grey skin covered with close-set nodules, and this nubbly ‘shagreen’ surface gave her a secure grip. The talons emerged from high up in big ‘knuckle’ pads at the ends of her toes. They were glossy dark grey growing from a straw-coloured base, about three-quarters of an inch long (20mm-plus), curved like sabres and needle-pointed. When Mumble stood on a flat surface the upwards curve of the claws from their base in the pads kept all but the points off the ground. When she closed one foot to ‘put it
in her pocket’, or both of them in sustained flight, the front and rear talons folded from the knuckle pads right inwards under the toes, like the opposed blades of a jack-knife closing beside one another. I learned that the inner front and rear toes (which do the primary gripping, like our forefinger and thumb) were controlled by a sort of ratchet that allows owls to maintain a crushing grip without consciously exerting constant muscular effort – the grip that enables them to kill their prey almost instantly.

* * *

I badly wanted to examine Mumble’s wings in detail, but – naturally – she refused to tolerate any handling of these delicate miracles of engineering. Her short flights, and her stretches during grooming, were too brief for me to note the details properly, so I had to resort to studying published illustrations, later comparing these with her moulted feathers.

Another glance at the skeleton drawing on
here
will show how the wing has evolved from the original reptilian ‘arm’ or front leg. From the shoulder joint outwards, it now has three sections that appear to us to be of roughly equal length, though the length of the outer section is almost entirely made up of feathers. The single ‘upper arm’ bone or humerus ends in an ‘elbow’; from this joint the double ‘lower arm’ bones, the ulna and radius, flex forwards, ending in a ‘wrist’; and from that the partly fused and elongated ‘fingers’, the carpo-metacarpus, flex backwards. (Both the shoulder and the ‘elbow’ joints are invisible to
us, hidden by the thick feathers covering the structure.)

Since tawnies are woodland owls, who have to be manoeuvrable to make agile banks and turns during flights between close-set trees, their wings are relatively shorter and broader than those of owls that make more extended flights in the open, like the Barn and Short-Eared. However, for a grown female the wingspan still measures more than a yard, with distinctly separated feathers at the tips. From the tip inwards to about the mid-point of the trailing edge, each of Mumble’s wings was furnished with ten of these large, strong pinions or primary flight feathers. From the mid-point inwards to the body, the trailing edge continued in a similar row of anything between eleven and nineteen smaller secondaries (some sources describe the smallest of these feathers, closest to the body, as tertiaries).

On the leading edges of her wings, about one-third of the way in from the tip and immediately outside her ‘wrists’, she had separate, outwards-pointing
alula
feathers, growing from the vestigial ‘thumb’ of the reptilian ‘hand’ that had evolved into the outer one-third of the wing. This bone could be manipulated independently, so the feathers acted like the leading-edge flaps on aircraft wings. (Though in fact, of course, the correct way to describe the resemblance is that the aircraft’s flap acts like a very crude and clumsy imitation of the
alula
.)

Most birds – and some owls – have stiff, glossy flight feathers (
remiges
, oars) that cut through the air like knives, but Tawny Owls are among those species that have adapted to sacrifice sheer speed in return for almost
noiseless flight. The individual
barbules
along the leading edges of their primary feathers are not ‘zipped together’ but free, forming a fine comb or fringe. This fringed effect, and a velvety pile over the surface of the feathers, breaks up the turbulence of the air passing over the wings, and thus reduces its rushing sound to almost nothing. Coupled with the low wing-loading that makes constant flapping unnecessary, this gives the owl the gliding, virtually silent flight that is so invaluable when hunting. There is no noise of beating wings to warn its prey, nor to interfere with the incoming higher-frequency sound signals being processed by its sophisticated ear-and-brain computer.

On the top surface of Mumble’s wings the background colour of the primaries and secondaries ranged from mid-brown through pale brown to off-white at the trailing edge and tip, and each was barred across with five or six irregular dark brown stripes. From the leading edge of the inner part of the wing a series of overlapping rows of velvety brown covert feathers, increasing in size from front to back, ‘faired in’ the bases of the secondaries and primaries. The undersurfaces showed the same basic camouflage pattern as the top, but paler, as if misted over with a spray of pale greyish-cream colour.

Mumble usually only opened out the three sections of her wings to full spread when she was either flying or giving them a thorough stretch. The rest of the time she kept the outer two-thirds – from the ‘elbow’ forwards to the ‘wrist’, and from the ‘wrist’ backwards to the ‘fingertips’ – folded up together in a tight inverted V-shape, with the
primaries closing underneath the secondaries. From its normal position in repose the thick, smoothly feathered apex of this V looked to human eyes like a shoulder, but it was in fact the bent ‘wrist’, held pressed against the side of her invisible shoulder joint. Most of the time she kept what had been the reptilian ‘upper arm’, between shoulder and ‘elbow’, pressed back tightly against her side; she only partially extended it in order to move the two outer sections around as a single thick, closed fan of featherwork.

* * *

While Mumble was patrolling around the living-room floor one evening, her vainglorious strut suddenly reminded me of a character in a Japanese samurai film. Like some warrior played by Toshiro Mifune, she had the touchy air of someone who is ready, at an instant, to take furious offence over some imagined slight. She carried her head up and back with her ‘chin’ tucked in, and darted jerky little glances in all directions; once the fancy struck me, I could almost see a tense hand resting on a pair of sword-hilts.

This conceit was followed immediately by another – that her feathers actually had something in common with a sixteenth-century samurai’s lamellar armour. In both cases, many small individual elements – for the samurai, laced-together iron strips, and for Mumble, individual feathers – appeared to be assembled into a series of separate larger panels. Like some wealthy
daimyo
’s lacquered, silk-laced composite cuirass, they were intricately barred and powdered with the subtlest of colours. During her first
couple of months, when she had still been wearing what looked like a one-piece Babygro of woolly down, this had seemed to move – if at all – like a single surface. Once she began to come into feather, however, her selective control of her plumage became fascinating to watch.