EYES TO ENVY.

Hawera Star, Volume XLV, 22 August 1925, Page 11

EYES TO ENVY.

BIRDS’ WONDERFUL SIGHT

NATURE’S AID TO HUNTING.

■ Although many of the feathered creature* which he mentions are unknown in New Zealand, the references made by this writer in The Times to the importance of their vision to birds of all climes and sizes will be read with interest by students of Nature: Unlike most beasts of prey, birds hunt by sight, and their vision rs noth acute and varied. Where the carcase is, the vultures are gathered together out of the blue by a .system like the did telegraphs or sem-aplmies: cue •bird spies its prey far below and the others flock to ine descending i peek in indefinite succession. While tii. eyes of these great birds excel our own in range, those of the warblers and tit-mice and flycatchers are as remarkable for microscopic precision. Watch lh 0 common spotted flycatchers hawking from the net of the lawn-teuiri's post in the garden, or from a gravestone in sumo grassy country churchyard, and how seldom we detect on tv halt it preys! We see the spot in the .air where it feeds, and the snaps, ot its bill show how the air teems with inviisibile insects. It is the same with the ismialler titmice among the winter twigs, with the cluiffchaff and willowwren among the July foliage, and, above a 111, with the minute yet sturdy gold,crest, because in its curious indifference to man .it lets us watch it mo-re closely. Sometimes, and especially in iSiUimimer, wo see thd siearohing bill, at the dictate o-f the keen eyes, iseizo a grub, a fly, a/ spider; but far more often the little bird seems to rehearse am endless hungry' pantomime, ; aml we marvel how its eyesight outwits us. Birds’ e-ye-s are many coloured, but this variety seems an example of na-t-

lire’s free variation, and to nub,serve no utilitarian end. The jackdaw's ,eyo is no sharper because of its pallor, and tlie goshawk’s brilliant yellow ap-pear.-i to give it no practical superior;.ity over the falcon brown. Some ioiixls’ eyes seem subdued to that they (work in, like the kimmergeiers, with K.heii' hue of bicod, or the cold green pupils of the cormorant that fan as its food in the water's. Such eccentricities acid greatly to a bird’s personality; but tile colour of its eyes i.s of dibtie importance in -its aicciv-ities com-ipa-ied with their position and size. Mankind has its eyes placed to look ,forward; but, Hike the horse and the hare, most birds have their eyes at the sides of -their head, like man’s ears. |This lateral -adjustment gives them a wider range of observation than that of man. They can see farther behind the-m, and thus are partly guarded against -a .stalking enemy, but -arc lie-sis apt to combine their double iv is ion into an effective whole. .It is noticeable that many birds which need tire keenest or longest sights, such as tho eagles and falcons aawl owfe, have -eyes set in tho front of their heads, much like man, and consequently have half-human faces. Many birds turn one eye sideways when watching closefly, just as wo turn one ear, putting a band 'behind it, when our hearing begins to fail us, or we wish to catch a (distant, sound. When, we .see a thrush cocking itisi head at/ the turf, and presently tugging out a hidden worm, this, is sometimes claimed -as a triumph of hearing. But a magpie will, peer in ithe same way into a knot-hole or a femrrowbone; -and there is little doubt. Itha-t the thrush sees a slight heave of.l

the soil, and that a man’s ear and a •oil'd s eye are useu m tne same way because they are similarly imp.auted.

Bints that, hunt in the dusk are usualy equipped with large eyes, to collect tlie teenier rays. 'that ns the ■secret of the great eyes of the ow'i, that is tare so solemnly oy day- ana dayflying owls, suen as tue slxoi t-eared ana hawk owls, are noticeably less moonfaced and more aquiline. \\ e see tills contrast of equipment. in the eoinmonent 'birds which peeic about our gardeu lteors. The size of the eye eori.ei.spouiiis roughly with the birds' bedtime. Those small positive eyes ox >the sparrow were mauo for broad daylight; its promptitude deserts it when tlie hews fall, and it Hocks early to the 'ivy where if sonnies on its untidy mattress. Bub the redbreast, with it* . large and liquid eye, is an evening third: it haunts the twilit paths, picking here and there a slug, but seeming to take pleasure in their coolness land mystery. Wo might expect cormorants to have large eyes, to gathei the veiled rays beneath the waters as the owl focuses the murky night. The sm.ailnesis of their eyes suggests that they do not view their prey at Jong range, but search closely lot it. > Buds’ eyes have a membrane to cleaz ■them, besides their eyelids; it is this screen which ironically fiickeis between ■us, like a well-strangled yawn, when •wo are .staring at some well-bred eagle ■in captivity. Most of the new-lledgeii •birds; with round eyes, which abound ■now in the garden bushets, have but a dim sense of what they sec. Their 'ayes do net focus upon us, and they have an air of looking through us which is uncanny; but their slight stir fc>f withdrawal at last shows that fear is latent and growing. it is 'amusing to see a bird maiko a mistake, as when a herring gull roaming the cliffs Isees the stir of a little gust on the cove’s surface, and plunges as if it were a fry-shoal. Such a slip seems to bring down birds from their daunting height of skill in tracking teas and ,lands from South Africa to some Staffordshire cowshed, as it has been proved that the swallow can. The gradual training of a homing pigeon ami the confusion that overwhelms migrating 'birds on a foggy night seem to ■show that eyesight must have a great ■share .in forming their sense of direction.