KAKA PARROT.
KAKA PARROT.
“During gloomy weather it is often very active; and sometimes even in the bright sunshine a score of them may be seen together, flying and circling about high above the tree-tops, uttering their loud screams, and apparently bent on convivial amusement. When the shades of evening bring a deeper gloom into the depths of the forest, and all sounds are hushed, save the low hoot of the waking Morepork, or the occasionalcheep-cheepof the startled Robin, the Kaka becomes more animated. It may then be heard calling to its fellows in a harsh rasping note, something like the syllables ‘t-chrut, t-chrut,’ or indulging in a clear musical whistle with a short refrain. It is strictly arboreal in its habits, and subsists to a large extent on insects and their larvæ, so that it is probably one of our most useful species. Where they exist in large numbers they must act very beneficially on the timber forests; for in the domain of Nature important results are often produced by apparently trivial agencies. Like all the honey-eaters, while supplying their own wants, they do good service with their brush tongues by fertilising the blossoms of various trees, and thus assisting in their propagation; while, on the other hand, the diligent search they prosecute for insects and grubs, and the countless numbers daily consumed by each individual, must materially affect the economy of the native woods. On this latter point Mr. Potts has furnished the following valuable note:—‘Although so often accused of injuring trees by stripping down the bark, from careful observation we do not believe a flourishing tree is ever damaged by its beak. It is the apparently vigorous, but really unsound, tree that is attacked, already doomed by the presence of countless multitudes of insects of many varieties, of which it is at once the food and refuge, either in their perfect or larval state. In the persevering and laborious pursuit of this favourite food, the Kaka doubtless lends his assistance in hastening the fall of decaying trees; the loosened strips of bark dissevered admit to the exposed wood rain and moisture collected from dews and mists, to be dried by evaporation by the heat of the sun, by the desiccating winds, only to become saturated again. Under this alternation the insidious fungi take root, decay rapidly sets in, the close-grained timber gives place to a soft spongy texture, branches drop off, and gradually the once noble-looking tree succumbs to its fate; but its gradual decay and fall, the work of years, has proved beneficial to the surrounding plants: the dropping of the branches admits light and air to the aspiring saplings, assists in checking the undue spread of lichens and epiphytes; and when the old stem falls, tottering down from its very rottenness, its place is supplied by vigorous successors.’
“In estimating the value of the labours of the Kaka as an insect-eater, it should not be forgotten that the family of Woodpeckers is entirely absent from our bird-fauna, and that upon this indefatigable climber devolves some share of the duty of representing that peculiar group of forest birds. How diligently the insects are sought for by the Kaka may be judged from the heaps of bark chips that lie beneath the decaying trees. Often it may be noticed on the ground tearing away the mossy clothing of the huge gnarled roots that spread around; even the soft rotten boughs are gnawed to obtain the larvæ of some of the larger bush insects.”
The Nestors vary immensely in colour, so that many of the plumages now known to be only occasional varieties have been supposed to be specifically distinct. They are birds of large size, and have the cere, or fleshy portion at the base of the bill, rather strongly developed, the bill being large and powerful. The colour is of an olivaceous brown, with a dash of dark red, the crown grey, and the ear-coverts shaded with orange, the cheeks with dark red, as also are the lower back, rump, and upper tail-coverts and abdomen.
The structure of the bill of the Parrots is so remarkable as to be worthy of a more extended description than could be given to it when it was incidentally referred to in our account of the osteology of birds in general. The way, however, in which the upper and lower jaws are connected with the skull was there explained, and a reference to the description on pp. 241–2 will save the necessity of much repetition now. That account embraced all members of the class of birds; here we are dealing only with certain peculiar modifications.
If the skull of an adult bird of any familiar type, such as a Crow, be examined, it will be seen that the bones of the upper jaw are apparently continuous, and form one piece, with those of the forehead and sides of the head. There is nothing that looks like a joint, or “articulation,” between the bill where it is attached to the forehead above, or to the long jugal arch (“quadrato-jugal”) that runs each side to reach the quadrate bone, or to the flattened bones that help toform the palate below. But if the skull of this same bird had been carefully examined in an earlier stage of its existence, it would have been found that the bones were at first distinctly separate at the three points here indicated, and were merely connected by a soft membranous substance. In many birds this “inter-osseous” membrane connecting the bones of the upper mandible with the skull proper never becomes true bone at all, but remains throughout life more or less soft and flexible. And by this means a sort of elastic joint is established, conferring upon the beak a certain range of up and down motion.
Now in Parrots, more conspicuously than in any other birds, each of these joints, not alone that of the beak with the forehead, is converted into a true hinge-like articulation, so that the upper jaw can be raised to a very considerable extent; and to effect this motion the muscles of the palate are developed into a somewhat complex apparatus.
If the figure be examined, the actual relations of the bones can be readily made out. Atais seen the line where the bill is articulated to the frontal bones. Atbis the joint which the bill makes with the long jugal bone (j). And atcis its articulation with the palatine bone (pl).
SKULL OF THE GREY PARROT.
SKULL OF THE GREY PARROT.
But it is not this mobility of the upper mandible alone that gives the characteristic aspect to the Parrot’s face. There are several other points in which Parrots agree, with a wonderful uniformity, among themselves, and differ from most other birds. Besides the absence of certain important processes, called “basi-pterygoid,” the ploughshare-like bone, or “vomer,” is altogether wanting. The maxillo-palatines are very largely developed and spongy; they unite with one another in the middle line, and with the thick wall of bone into which theseptum nasiis in Parrots strongly ossified, and thus fill up almost the whole base of the beak. The long palatine bones proper are remarkably flattened from side to side for most of their length; their hinder edges are more or less notched, and quite free from any bony attachment; and they are united at about the hinder third of their length by a plate-like extension from each. The scoop-like lower mandible, with its tip that seems to have been cut off “square,” to be out of the way of the strongly-hooked upper jaw, is too familiar to call for any particular description.