Birds and Birding's Guide to:

Watching THE CUCKOO-LIKE BIRDS

(Order Cuculijormes)

HIS order is the last great group in which the ambiens muscle, already spoken of as being of high classificatory value, is present, in addition to which all possess a”yoke-toed”(zygodactylous) foot, and the bridged or desmognathous type of palate. This so-called”yoke-toed”condition is brought about by the first and fourth toes being permanently directed backward, a manner quite different, it will be recalled, from the way in which it is accomplished in the Trogons, though similar to the arrangement in Woodpeckers, Puff-birds, Barbets, etc., and on which account they were all formerly placed together.

However, the arrangement of the deep tendons of the foot is sufficient in conjunction with the above-mentioned characters to distinguish the Cuculijormes, and is very different from that in the Woodpeckers and allied forms. In these tendons the anterior portion splits into three branches, which supply respectively the second, third, and fourth toes, while the posterior portion supplies only the hind toe, the two tendons being bound together by a band {vinculum).

This type of tendon arrangement is of quite common occurrence, being that which obtains in Gallinaceous birds,—Herons, Cranes, Rails, Gulls, Auks, etc., — and differs from that in the passerine birds simply in having the tendons bound together by a vinculum or band.

The Cuculijormes embraces two suborders, —the Cuculi, or Cuckoos, and Plantain-eaters, and the Psiltaci, or the extensive group of Parrots. In the first suborder the young are born naked and do not pass through a downy stage before acquiring their feather covering, while in the typical members the contour feathers are without an aftershaft, and the oil-gland is present but nude.

The tail-feathers are normally ten in number, but in some New World forms there are but eight. In the Parrots (Psittaci), on the other hand, the young pass through a downy stage, the contour feathers possess an aftershaft, and the oil-gland is usually present and tufted, though entirely wanting in a few genera. As regards the tail-feathers, the normal number is twelve, a single Papuan genus possessing fourteen. Of the structural characters it may be mentioned that the Parrots possess the permanently zygodactylous feet, a movable upper mandible, and a short, stout, strongly hooked bill, while there are no caeca and the gallbladder is usually absent.

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