Something /Voout Ipiras as a Oroup 



No FORM of wildlife has such a popular appeal to the general public as 

 birds, and none a greater fascination. This is due to the combination of 

 characters that make them spectacular, noticed even by those who are not 

 particularly interested in the out-of-doors. The activity, color, song, nest 

 building, care of the young, and migration of birds all combine to bring 

 them to popular attention. 



Birds are easily characterized, the old definition that "A bird is an 

 animal with feathers" being still perfectly sound biologically and more 

 easily remembered than more involved statements of structural differences. 



In comparison with other groups, birds are remarkably homogenous 

 a fact that for taxonomic purposes has led to comparative exaggeration of 

 the differentiating characters present and any who doubt it have only 

 to pluck a few birds and view them without their feathered coverings. 

 "Fine feathers" do "make fine birds," for without the feathers the 

 brilliant orioles have a remarkable superficial resemblance to the dull- 

 colored sparrows. Examining plucked birds and forgetting skeletal and 

 internal characters, we see that aside from feathers the chief differences 

 are those of size, length of neck, and length, size, and shape of bills, legs, 

 and feet. Differences in the abundance, color, structure, size, and shape 

 of the feathers, particularly those of the head, wings, and tail, combined 

 with the structural variations just mentioned give us the remarkable 

 variety of birds with which we are privileged to be acquainted. 



Aside from these differences in superficial appearance, birds have certain 

 common characters that set them apart from other groups. All the well- 

 known birds have skeletons of strong, light bones with the forelimbs 

 modified into organs of flight. Examining the skeleton, we find that the 

 bones in the fingers and wrists are more or less fused to form at the 

 extremity of the wing a single strong bone that supports the primaries, 

 the feathers chiefly used in flight. The rest of the wing is composed of the 

 secondaries, which are on the forearm, and the tertials, inserted in the 

 upper arm. These three groups of feathers compose the fan, or wing, 

 surface that makes flight possible. The smaller feathers at the base of 

 the wing are chiefly valuable for form and covering. The great differences 

 in wing shape, from the shortly rounded wings of the rails, which are 

 scarcely able to sustain the flight of the birds, to the enormously elongated 

 flight organs of the albatross, are produced by the variation in number, 

 shape, and comparative length of the flight feathers. 



