Sept. U, 1883.] 



♦ KNOWLEDGE ♦ 



161 



^^' MAGAZINE OF^CIENCE 



PLAINLY"W0RDED-£XACTLYDESCR1BED 



LONDON: FRIDAY, SEPT. 14, 1883. 



Contents of No. 98. 



PAGB I PAGE 



A Naturalist's Year. The Bam Owl i Tricycles 169 



Flies. By Grant Allen ISl W inds as Projectiles 170 



Pleasant Hours with the Microscope. ' Dangers of Sea Bathing 171 



{.Illut.) ByH. J. Slack 162 : Editorial Gossip 171 



The Harrest Moon. (IUu».) By Face of the Sky 172 



E. A. Proctor 164 Correspondence: The Bennett 



The Chemistry of Cookery. XVIII. , Battery — Small Wheels for 



By W. Mattieu WilLiams 165 Tricycles— A Curious Pheno- 



The Morality of Happiness. By menon— The Comma, ,ic 173 



Thomas Foster 166 i Our Mathematical Column 175 



Eyolution of Human Physiognomy. Our Whist Column 175 



(lUua.) ByE. D. Cope 168 | Oar Chess Column 176 



A NATURALIST'S YEAR. 



By Grant Allen. 



XXI.— THE BAEX OWL FLIE.S. 



AS the shades of evening begin to fall, the big barn owl, 

 from the top of the old broken sham-castle on the 

 hill-side, crawls out regularly every night from the over- 

 sheltering ivy, and sets forth stealthily upon his predatory 

 expedition in search of stray wandering rabbits, rats, and 

 mice. A weird and uncanny thing he is to be sure, 

 worthy to be held in superstitious awe as a bird of ill- 

 omen ; and yet, I suppose, he merely flies by night from 

 necessity, not from choice, because the creatures on which 

 he has adapted himself to prey come out by night for their 

 own feeding-time. Your common barn owl, in fact, is 

 one of the remoter hangers on of civilisation, an outcast 

 who follows close on the heel of the agricultural pioneer 

 all the world over, till at last it has become almost impos- 

 sible to say in what countries he is really indigenous, and 

 in what he is merely a perfectly naturalised alien. The 

 reason for this is simple and obvious enough. Wherever 

 man sows and plants, the rat and the mouse, in one 

 or other of their local forms, thrive and multiply 

 most exceedingly. Kot only in houses, but even 

 more in cornfields, barns, farmyards, and granaries, these 

 unwelcome guesis of civilisation ilourish everywhere in 

 the greatest abundance. Now, the barn owl was from the 

 \"ery beginning, apparently, the member of his own race 

 most peculiarly adapted to prey remorselessly upon these 

 small and coni|)arative!y defenceless quadrupeds. So, as 

 the mice, rats, and shrews increased in numbers with the 

 increasing supply of food aftbrdcd them by the grain or the 

 insects of cultivated fields, in like manner did the pre- 

 daceous Ijarn owls increase side by side with them to prey 

 upon them, as their natural food. All the owls, in common 

 with other birds of prey, have a convenient habit of 

 rejecting the bones of their victims from the stomach, un- 

 digested, in little pellets, which saves their aliineutary 

 canal a lot of useless labour ; and the examination of these 

 pellets, in the case of our friend the barn owl, sufllciently 

 dispels the wicked calumny of gamekeepers that he feeds 



mainly upon young birds, as the bones of which they are 

 composed are almost entirely those of small mice, voles, 

 shrews, and other petty rodents or insectivores. 



Though it is not quite formally correct to describe the 

 owls, after the good old fashion, as the nocturnal birds of 

 prey (for some of them hawk about in the broad daylight, 

 while at least one of the falcon tribe, or so-called diurnals, 

 has, j)er contra, acquired the habit of hunting bats by 

 night), there can yet be no doubt that the owls as a group 

 have really gained most of their distinguishing charac- 

 teristics in adaptation to a night-flying existence. Their 

 very shape and structure marks them out at once as widely 

 different in liabit from the frank and bold birds of prey, 

 like the eagles, hawks, and falcons, which mostly pursue 

 their quarry in the open sky. Their oddly- shaped legs 

 fit them for squatting in the peculiar, sleepy, owlish 

 attitude ; their short necks and clumsy bodies are 

 better fitted for prowling in the dusk after ground 

 animals and game birds, than for pursuing swiftly-flying 

 creatures like those which form the main food of the 

 rapid hawks and falcons. But the big head, with its ruff- 

 like disc, which is perhaps the most marked feature in our 

 common English owl, bears still more distinct reference to 

 the specially nocturnal habits of the entire race. Owls, 

 apparently, are more highly developed hawks, specialised 

 in many respects for night-flying liabits ; and therefore 

 their sense-organs have had to undergo the usual modifi- 

 cations in adaptation to their peculiar environment. As in 

 most lemurs and other advanced nocturnal mammals, the 

 eyes are very large and noticeable, and are surrounded by 

 a sort of reflector of curiously-arranged concentric feathers. 

 They are admirably adapted for vision in the dusk or with 

 a minimum of light; but, at the same time, the peculiar 

 organs in the retina which are supposed to be employed 

 in the perception of colour are entirely absent. It is 

 a noteworthy fact in this connection, that owls themselves 

 seldom show any traces of colour in their own plumage, 

 other thim various shades of black, white, grey, and brown. 

 Their hues are generally protective, and enable them to 

 pass mmoticed in the daytime upon the bark of trees. 

 This is, indeed, what one might naturally expect, because 

 Mr. Darwin has shown that ornamental colouration in 

 birds is due almost entirely to the sexual selection of the 

 most beautiful mates ; and a group like the owls, which 

 are actually destitute of the nervous apparatus for per- 

 ceiving red, blue, green, and yellow, cannot well show a 

 marked preference for such gaudy hues in their own 

 fellows. As a matter of fact, the few decorative ad- 

 juncts to be found amongst them are entirely con- 

 fined to pure white plumage, as in the snowy owl (a 

 day-flyer), or to tufts and rings of feathers in the most 

 conspicuous and visible positions, as in the long-eared owl 

 of our own islands. In this respect, owls form a complete 

 contrast to such brilliant fruit-eating groups as the parrots 

 or the toucans ; yet it is interesting to observe that one 

 very aberrant New Zealand parrot, wliich is also nocturnal 

 in its habits, and closely resembles the owls in appearance, 

 down even to the possession of the distinctive disc around 

 the eyes, has toned down the prevailing green of its 

 ancestral colouration into a very owl-like shade of dingy 

 olive-brown, speckled with tawny yellow. This is one of 

 the numerous cases which show us that similarity in mode 

 of life will produce strong adaptive external resemblances 

 between very diverse creatures originally descended from 

 extremely unlike ancestral lines. 



Nocturnal animals require largely to supplement sight by 

 hearing, a fact which is well illustrated in the enormous 

 e.xternal etirs and peculiar apprndnges of many advanced 

 forms of bats. In the owls, evidence of similar adaptation 



