Disguise.
Next comes concealment by means of Disguise.
On the right hand of the accompanying illustration is shown a singular mode of concealment adopted by the Barea, a warlike and predatorial tribe of Abyssinia. When Mr. Mansfield Parkyns was resident in Abyssinia he fell in with the Barea, through whose country he had to pass.
“Scarcely had we passed the brook of Mai-Chena when one of our men, a hunter, declared that he saw the slaves. Being at that time inexperienced in such matters, I could see nothing suspicious. He then pointed out to me a dead tree standing on an eminence at a distance of several hundred yards, and charred black by last year’s fire.” Here I must explain that in Abyssinia, as in several other parts of the world, the ground is annually, cleared of its superabundant vegetation by setting fire to it, and allowing the flames to burn themselves out.
“However, all I saw was a charred stump of a tree and a few blackened logs or stones lying at its feet. The hunter declared that neither the tree nor the stones were there the last time we passed, and that they were simply naked Barea, who had placed themselves in that position to observe us, having no doubt seen us for some time, and prepared themselves.
“I could scarcely believe it possible they could be so motionless, and determined to explore a little. The rest of the party advised me to continue quietly in the road, as it was possible that, from our presenting a rather formidable appearance, we should pass unmolested; but so confident was I of his mistake, that, telling the rest to go on slowly, as if nothing had been observed, I dropped into the long grass and stalked up towards them.”
“A shot from my rifle at a long distance (I did not venture too close) acted on the trees and stones as powerfully as the fiddle of Orpheus, but with the contrary effect; for the tree disappeared, and the stones and logs, instead of running after me, ran in the opposite direction.”
“I never was more astonished in my life, for so complete was the deception that even up to the time I fired I could have declared the objects before me were vegetable or mineral—anything, indeed, but animal. The fact was that the cunning rascals who represented stones were lying flat, with their little round shields placed before them as screens.”
This stratagem is shown on the right hand of the illustration.
On the left are a few of the innumerable instances in Nature where Concealment is obtained by imitation.
The three examples which are here given are familiar to all entomologists.
The upper figure represents two of the Geometra or Looper Caterpillars, as they appear when at rest, and affixed to a twig. This appears to be a singular attitude of rest, but it is one in which they delight, and in which they remain for hours together, the claspers at the end of the body tightly grasping the branch, and the whole body held out so straight and motionless that it is hardly possible to believe that a veritable twig is not before the eye. The colour is that of the twig, and the different segments of the body look exactly like the little irregularities and projections of a young twig.
I have more than once seen a novice in entomology unable to distinguish these larvæ, even when the branch was pointed out, and there were several upon it.
Just below the Loopers, and on the left hand of the illustration, is shown the well-known Leaf-insect (Phyllium). These strange beings have the elytra and the flattened appendages of the legs so exactly like leaves that the most experienced eye can scarcely distinguish them from the leaves among which they are placed. Even when they have been on a small plant, such as a myrtle in a flower-pot, I have had the greatest difficulty in finding them, and have seen people examine the plant, and then go away declaring that no insects were on it.
On the right hand, and just below the looper caterpillar, is the common Lappet-moth of this country, shown in its position of rest.
When it assumes this attitude, it looks exactly like a withered leaf, the resemblance extending not only to the form, but the colour. All entomologists are familiar with many similar examples in insect life. The common Tortoise-shell Butterfly, for example, has a way of settling on patches of red soil, with which it harmonizes so well that it can hardly be seen. The various moths, also, are in the habit of resting on tree-bark, palings, and other objects, to which they instinctively know that they assimilate in hue. Many a beginner in entomology will pass a wooden fence or a wall, and not see an insect on either, while an adept will follow him and take twenty or thirty good specimens.
The last figure in the illustration represents a Ptarmigan (Lagopus vulgaris) in its winter dress. These birds have two differently coloured dresses, one for summer and the other for winter, and both adapted for concealment by imitation. In the former dress it is mottled with various shades of blackish brown, yellow, and white. As the bird is in the habit of settling among the grey lichen-covered stones on the sides of rocky hills, these colours harmonize so exactly with them that a Ptarmigan may almost be trodden upon before it is perceived.
In the winter, when the snow covers the whole country with one uniform sheet of white, except where the wind blows the snow aside, and exposes the underlying stones, the Ptarmigan assumes a different plumage, being almost entirely white, except a black streak over the eye, and the outer feathers of the tail, which are also black. Thus the bird becomes almost indistinguishable from a snow-covered stone, especially as it has a habit of squatting motionless and silent when it takes alarm.
The reader may, perhaps, remember that the common Stoat also has a summer and winter dress. The ordinary colour is rich reddish brown above, and white beneath, with a black tip to the tail. In the severe winters of Northern Europe the Stoat exchanges his ruddy coat for one of pure white, and is then known by the name of Ermine. It is remarkable that in the winter dress both of the Ptarmigan and Stoat the tail is black, while the rest of the coat is white.