ANATOMY OF BIRDS
Bird Wings
Bird Bone Structure
Bird Feathers
Bird Pectoral Muscles
Bird Sternums
Bird Leg Bones
Bird Perching Bones
Bird Pelvic Bones
Bird Vertibrae
Bird Scull Structure
Woodpecker sculls
Bird Beaks
ANATOMY OF BIRDS
GEOGRAPHICAL DISTRIBUTION
MIGRATIONS OF BIRDS
CLASSIFICATION OF BIRDS
LIZARD-TAILED BIRD
AMERICAN TOOTHED-BIRDS
THE OSTRICHES
THE RHEAS
EMEUS AND CASSOWARIES
THE TINAMOUS
THE KIWIS
THE PENGUINS
LOONS AND GREBES
ALBATROSSES & PETRELS
STORK-LIKE BIRDS
GOOSE-LIKE BIRDS
FALCON-LIKE BIRDS
FOWL-LIKE BIRDS
CRANE-LIKE BIRDS
PLOVER-LIKE BIRDS
CUCKOO-LIKE BIRDS
THE ROLLER-LIKE BIRDS
SPARROW-LIKE BIRDS
Birds and Birding's Guide to:
Watching THE ANATOMY OF BIRDS
Bird Pectoral Muscles
The wing is supported by the coracoid, a bone abutting on the front of the breast-bone and raking forwards and upwards. This bone, represented in the higher mammals by a mere process on the shoulder, forms half of the shoulder joint in reptiles and also in the Echidna and Platypus, and by far the greater part of the shoulder joint in birds, that part of the shoulder blade being much reduced.
In perching birds the coracoid is long and slender, and in birds which soar or sail it is shortened and broadened, for it is a rather curious fact that while the amount of muscular power employed in flight is much smaller in sailing birds than in others, the support for the wing is much more strongly built. In the Frigate-bird, which is perhaps the most expert bird of flight, the area of wing muscle is proportionately smaller than in any other bird, while the wishbone is united at its apex with the breast-bone and soldered to the coracoids at the other end, thus forming a rigid support for the wing.
The shoulder blade is slender and as a rule more or less pointed, the Penguins being exceptional in having a broadly expanded scapula, while the Woodpeckers are characterized by having the end bent downwards. Attached to the coracoids in front is the wishbone, which represents the clavicles or collar bones of other animals. This is usually”U"-or”V”-shaped, with the apex near the keel of the sternum or even united with it, as in the Steganopodes. In some Parrots and Toucans the upper portions only of the clavicles remain attached to the coracoids, and in the struthious birds, save Emeu, clavicles are entirely lacking. In birds of prey the clavicles are broadly”U”-shaped and heavily built, serving to brace the wings apart, but in the majority of birds they are of little structural importance, and in such admirable flyers as the Hummers are practically of no use.
The breast-bone, sternum, bears a direct relation to habits, and to a less extent is valuable in classification. While the terms Ratitse and Carinatse, keelless and keeled, are convenient in forming a key, and the corresponding conditions were formerly held of primary importance in classifying birds, they have been abandoned by the best anatomists, as they do not express the truth. The development of the keel of the sternum bears a direct relation to the extent to which a bird moves its wings, whether in flight or swimming. Birds which do not fly have the keel of the sternum small or absent, according as the power of flight has been lost, geologically speaking, for a longer or shorter period of time.
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