Woodpeckers.

THE Picida, or Woodpeckers, are a very remarkable and numerous family. They are appointed to search for and subsist upon those insects or grubs which undermine the bark of trees, or bore into the sapless wood of such as are in a state of decay or have already ceased to derive nutriment from the ground. A remarkable peculiarity of character is given to these birds, to enable them to procure their appropriate food, which is secure against the attacks of every other bird or animal. The healthy tree has but little attraction for them, it is the aged, deathstricken tree that is the province of the Woodpecker. Here the insect tribes find ample room, within the interstices and chinks of the dried wood and bark, to spread and multiply their race, and perforate with their tiny jaws the solid trunk of the largest tree; and here it is that the birds of this family exert their peculiar powers and labour for their food.

In order that they may be enabled to procure these insects, it is evident that some extraordinary means must be resorted to. They have to climb the vertical trunk; to cling to the bark with a firm hold, whilst they are engaged hammering with their hard bill against the bark or wood, until they have disturbed

the insects, or punched away the intervening portion of the wood.

Considerable strength of foot and power of grasping or clinging is requisite, in order that sufficient support should be obtained for the body in its perpendicular or spiral ascent of the bark of a tree. We accordingly find that, although short, the Woodpecker's feet are remarkably strong; two toes are directed backwards, and two are placed in front, these latter being joined together at their bases, and the whole of them being firmly articulated

at the joints. In the typical species, the exterior hinder toe is considerably lengthened, so much so as to be longer than the longest toe in front. The claws are strong and

much hooked. Those in front serve to suspend the weight of the bird, and those which are directed backwards have their principal action in tightening the hold of them. As an additional support, the tailfeathers, which are remarkably firm in their texture, terminate in rather firm points, which being pressed against the bark are of very great assistance to the bird in his perpendicular attitude. The legs are placed behind the centre of gravity, so that the weight of the bird assists in compressing the claws in the fissures of the bark, and presses the tail against the tree under them; and while the centre of gravity remains higher than the feet the bird is stable, without that exertion of the body which would prevent the

use of the beak and of the wings, if these should be necessary. But if the head were turned downwards, or the body even much out of the upright position, the principle of stability would be changed into a cause of falling. Hence, though these birds can run upwards, they come down backwards only, and that rather slowly and awkwardly; and they can get round only in an ascending spiral, hence they beat and hunt the trees from the roots upwards.*

The bill being required for the performance of a peculiar and laborious operation, that of punching or picking into the bark or alburnum of trees, is accordingly adapted in the most beautiful manner for such a purpose. It is, in the typical species, perfectly wedge-shaped; both mandibles are of such an equal size and thick

the middle; the bill gradually becomes smaller from the base, and its circumference would be cylindrical were it not for certain ridges, which form little projecting angles, so that its section appears nearly hexagonal; the end has not a sharp point, but a perpendicular edge, like that of a wedge or hatchet.† This particular structure is not observed in the Green

*Feathered Tribes of the British Islands.

+ Swainson.