Corvus by Esther Woolfson Page A

was prepared to live and let live.
    While the favela house lacks style, it’s in this modest dwelling that Chicken has place and opportunity to do at least some of what all corvids do: preen and perch, roost, hide and retrieve, call and feed and bathe.

    In spite of our years together, aspects of Chicken are difficult to know. Her sight, being markedly different from ours, is one. Birds are thought to have the best vision of any vertebrate, the placing of their eyes determining not only nature and scope, but their capacity, depending on their species, to watch for predators or prey. Raptors and owls, both predators whose eyes are at the front of their heads, have binocular vision as we do, whilst birds such as doves, whose eyes are on the sides of their heads and are more often prey, have monocular vision, the ability to see objects with only one eye at a time. Birds with monocular vision usually have a very wide visual field; some, such as the woodcock, whose eyes are placed far back on its head, can see what is behind it more accurately than what is in front. (‘It could better tell where it has been than where it is going,’ according to the distinguished political scientist and nature writer Louis J. Halle.) Whilst human vision is limited by having three light receptors, or cones, by which colour is seen, birds have four or five spectrally distinct cones, sensitive to a far greater range of light waves, including ultraviolet, than humans, which may allow them to see twice as many colours as we do. They can also distinguish between wavelengths of the ultraviolet spectrum, a visual acuity that gives them fine perception in foraging, letting them identify a wide range of colours of food and natural objects. Raptors, although the most visually acute of birds, are thought to be able to see fewer colours than passerines.
    Chicken’s sight, once alarmingly acute, the sense which in birds is most highly developed, must by virtue of her useless eye be lessened, although most of the time it doesn’t seem so. (David has given hisopinion on the neurosurgical, or at least neurological aspects of her eye problem, which is possibly a cataract. His sister Zanna, an ophthalmic surgeon, has been consulted on the ocular. Both have agreed. The combined weight of their knowledge suggests that they’re not entirely sure what it is and in any case there’s nothing to be done.)
    Chicken’s right eye appears to compensate for the deficit in her left, for she is still able to see very small objects, a pine nut I have given to her lying on the floor, a crumb of something she considers desirable under the fridge. Because of the limited movement of the eyes in their sockets, birds’ necks have greater flexibility. Chicken has the enviable attribute of being able to turn her head upside down to look underneath the fridge or sofa. When we’re sitting together as evening wears on, she’ll descend to a roosting position, her feathers spreading a warmth across my knee, and she will appear, on one side, to be asleep. On the other, her eye is wide and bright and totally awake. ‘Is she asleep on your side?’ we’ll ask. The hemispheres of a bird’s brain alternate in waking and sleeping, the eye on the side of the somnolent, slow-brain-wave hemisphere closing. They can also sleep with both hemispheres at once. Research among ducks has shown that the ones at each end of a row of sleepers will keep the appropriate eye open, watching.
    Chicken trips sometimes over an item left lying on the floor, a piece of paper, something small, and I don’t know if it’s age or sight that causes her to do it. My heart stops briefly when she does, for whatever this is it is quite new.
    For reasons unknown, she nurtures a residual hatred for my specs,as a result of which I operate most of the time (as I suppose she does, on one side at least) in a hazed fog caused by her habit of standing on my shoulder and inserting her beak behind my ear to tweak my specs