Ornithology 9 or tlie Science of* Birds. 



The word ornithology is compounded of two Greek words, or- 

 nithos, of a bird, and logos, a discourse. It is that department of 

 Zoology which treats of the structure, habits, and classification of 

 birds. 



Birds are warm-blooded animals, and form the second class of 

 vertebrates. They are distinguished from mammals, not only by 

 their feathery covering, and the formation of the jaws or man- 

 dibles, which end in a horny bill, but by the production of their 

 young from eggs, and by the formation of the anterior limbs, which, 

 in their case, are developed into wings. 



It might, at the first glance, be supposed that birds are con- 

 structed upon a plan very different from that in the case of mam- 

 mals ; but a little careful study of the skeletons of each will show 

 that the two classes are built upon the same general and uniform 

 plan. 



The Bony Structure of Birds. 



The following is a brief outline of the skeleton or bony structure 



of birds : 



Explanation of Plate A. {Skeleton of a Bird.) 



a. Cranium or skull, b. Cervical vertebrae, c. The anchylosed or fixed vertebras 

 of the back. d. The caudal vertebrae, e. The ribs. f. The breastbone, g. The 

 furculla or merry-thought, h. Clavicula or collar bone. i. Scapula or shoulder 

 bone. k. Humerus or upper arm. /, m. The forearm (/, ulna; m, radius). 

 n. Metacarpus or hand bones, o. Phalanges of fingers, p. Femur or thigh bone. 

 q, q. The patella or knee pan. r, r. Bones of the leg (tibia fibula), s, s. Assa cal- 

 cis or heel bones, t, t. Metatarsal bones, u, u. Metacarpal bones, v. Ilium, 

 w. Pubis, x. Ischium bones of the pelvis. 



The Head. — The head consists of the skull and face. The 

 former is strongly arched, and consists of several bones. These 

 are united by seams plainly visible in the young birds ; but in the 

 old ones the bones become so compacted as to obliterate the seams. 

 The bones forming the face are small, but peculiarly prolonged. 

 They consist of the two upper jaw-bones and the plow-share, the 

 quadrate and the connecting bones, together with the lower jaws. 

 The large size of the cavities of the eyes and the thin partition 

 which separates them are remarkable. Sometimes holes are 

 pierced through this partition. Another peculiarity is the connec- 

 tion of the bones of the head with the vertebras of the neck, which 

 enables birds, with more ease than mammals, to move their heads 

 in all directions. 



The Vertebra. — The backbone of a bird is divided into the 

 vertebras of the neck, and of the back and pelvis, and the caudal 

 vertebrae. The number of vertebrae in the neck varies from nine to 

 twenty-three. They are distinguished by their mobility, while the 

 seven or eleven vertebrae of the back are immovable, and often 

 become compacted. The same maybe said of the seven or twenty 

 vertebrae of the pelvis. The caudal vertebrae, numbering from 

 five to nine, are more perfectly constructed than those of mam- 

 mals. The last one in birds, which supports the large feathers of 

 the tail, resembles a high three or four sided plate. The thin 

 broad ribs, whose number always corresponds to the vertebrae of 

 the back, are linked to these vertebrae, and with peculiar long 

 bodies, to the breast bone. They bear, with the exception of the 

 first and last, on their back border, hook-shaped processes, which 

 rest on the upper border of the following lower ribs. By this ar- 

 rangement the thorax is considerably strengthened. 



The Breastbone may be compared to a large shield, having 

 in the middle a ridge, varying in size and height according to the 

 power and size of the muscles attached to it, and, consequently, 

 according to the greater or less power of flight in the bird. In all 

 birds of prey, for instance, this ridge is very high, and bound with 



large and strong muscles ; but in birds incapable of flight, it is 

 wholly wanting. This ridge in some birds is hollow inside, to re- 

 ceive in its groove a part of the windpipe. 



The Pelvis of birds is principally distinguished from that of 

 mammals by its prolongation ; otherwise, it has the same bones as 

 the human pelvis. 



The Merry-Thought — The only other bone peculiar to birds 

 is the merry-thought or wish-bone, shaped like a horseshoe, and 

 fastened above to the collar bone, and below to the beginning of 

 the breastbone. 



The Wings. — The following are the different bones in the 

 wings of Birds : 



First. The shoulder bone. 



Second. The long and strong collar bones, articulated with the 

 breastbone, and above with the shoulder and upper arm bone, and 

 also, internally, with the merry-thought. 



Third. The humerus (upper arm bone), a long, hollow bone r 

 filled with air. 



Fourth. The ulna (elbow bone), which is usually stronger in 

 birds than in mammals of corresponding size. 



Fifth. The radius, which is weak in birds. The two latter 

 bones form the lower or forearm. 



Sixth. Two, sometimes three middle hand bones (phalanges), 

 three fingers and a thumb. The latter has, in some birds, a strong 

 hook-shaped nail covered with feathers. But in that case the 

 thumb has two limbs. 



Explanation of Plate B. {Structure of a Bird's Wing.') 

 The feathers marked from i to 10 are the primaries. A. The secondaries. 

 B. The winglet, spurious or bastard wing (thumb). C. The tertiaries. k. Humerus 

 or upper arm bone. /. Ulna of forearm, n. Hand bones, o. Finger bones. 



Birds' Legs consist of: 



First. A thigh bone (femur), and the leg bones (tibia and fib- 

 ula). The fibula is very small and immovably fixed (anchylosed) 

 to the tibia. 



Second. The metatarsal or shank bones. At their lower end 

 these bones have as many processes as there are toes. Each of 

 these processes is furnished with a pulley for moving the corre- 

 sponding toe. 



Third. The toes. There are usually four of these. This 

 number is never exceeded, while a few birds have only three toes, 

 and the true Ostrich only two. Three of the toes are directed 

 forward ; but one, corresponding to the great toe of the human 

 foot, is turned backward. This is the general rule. In some birds, 

 however, the great toe is altogether wanting, or only rudimentary ; 

 in others, such as the swallow, it is bent forward. In climbing 

 birds, such as the Parrot and Woodpecker, the outer toe and the 

 barb or great toe are turned backward. 



The Muscular and Nervous Systems. 



The Muscles. — Among the muscles are those that move the 

 wings, or the pectoral muscles. These are the most important, 

 and are more powerful than the similar muscles in mammals. 

 Compared with these, the muscles of the back are small. The 

 legs have strong muscles only on the upper and lower portions, and 

 only in such birds as have their legs feathered down to the toes. 



The Nervous System very nearly resembles that of mammals. 

 The brain exceeds the spinal nerve in bulk, but is more simple in 

 construction. It is divided into the greater and smaller brain. It 



