DISTRIBUTION-HABITAT— GENESIS AND DEVELOPMENT. 



Distribution of Birds. 



As far as the surface of the earth has been explored, birds have 

 been found in high northern latitudes, as well as between the trop- 

 ics ; on the plains, in the valleys, on the seas, and on the highest 

 mountains ; in fertile regions, and in deserts ; in primeval forests, 

 and on the barren rocks which are elevated above the surface of the 

 surrounding waste of water. Each separate zone has its peculiar 

 feathered inhabitants. Birds in general follow the laws of animal 

 distribution. They are found in great numbers in the frigid zones, 

 but are represented only by a few kinds. Toward the torrid zone, 

 the number and varieties rapidly increase. The water harbors and 

 supports but a few kinds, all of which have many points of re- 

 semblance ; while on the land, each zone and every locality has its 

 peculiar birds. Only a very few birds literally inhabit all parts of 

 the globe. Among these, so far as is known at present, there is 

 not a single land bird. The Turnstone (strepsilas interpres), for 

 instance, is found on the coasts in all parts of the world, because it 

 finds the same conditions of life, as well in the eastern as in the 

 western hemisphere. 



As a rule, the circle of bird extension reaches farther in the lon- 

 gitudinal than in the latitudinal direction. In the northern parts of 

 the globe, for example, are found many birds which abound more 

 or less in all other parts in or near the same latitude ; while a few 

 hundred miles to the north or south may produce a very decided 

 change in the number and kinds of birds. The flying capacity of 

 birds is not coincident with the circle of extension. Good flyers 

 may be confined to a comparatively small area, while indifferent 

 ones may have the range of a much larger circle. The regular 

 travels and migrations of birds do not enlarge their circles of ex- 

 tension. 



Species and Orders. — So far as at present known, the num- 

 ber of all the different described and non-described species of birds 

 may be estimated at about eight thousand. The order of Parrots 

 numbers three hundred and fifty ; birds of prey, four hundred ; 

 Pigeons, about three hundred ; scratchers, three hundred ; short- 

 wingers, ten ; stilts and swimming-birds, about six hundred kinds. 

 The remaining species are distributed to other orders. America 

 has a larger number of the different kinds of birds than any other 

 grand division of the globe. Next follow in this regard, in the 

 order named, Asia, Africa, Oceanica, and Europe. 



The following remarks may be made respecting different orders 

 of birds : The first order includes Parrots, wanting in Europe ; the 

 second order embraces Sparrows; the third order, Ravens; the 

 fourth order, birds of prey ; the fifth order, the spreading birds ; 

 the sixth order, singing birds, and the seventh order, climbing 

 birds ; the eighth order, Humming-birds, is confined to America ; 

 the ninth order, light bills, is chiefly found within the tropics ; the 

 tenth order, cooing birds, and the eleventh, scratchers, are repre- 

 sented in all parts of the world ; the twelfth order, short-wingers, 

 belong to Africa, Oceanica, and more generally to America ; the 

 thirteenth order, stilts, and the different orders of swimming birds, 

 have representatives in all portions of the globe. 



Habitat and Trades. 



The Habitat, or residence of birds, depends on the means it 

 affords them for a living. Birds that live on the water ascend high 

 mountains, and still higher rise the stilts, as they are less confined 

 to the water. The forests are densely populated with birds of va- 

 rious kinds. Oceans, seas, and lakes support millions of individ- 

 uals of the same or similar kinds. Hatching-time collects them in 

 multitudes on single rocks and islands. Frequently, the greater 

 the uniformity of the open or forest land, the greater seems the va- 



riety of the feathered tribes. The nearer an approach is made to 

 the equator, the greater also is this variety, as the countries of the 

 torrid zone present an increase of the varied conditions of life. The 

 like wonderful variety, too, obtains in countries where forests and 

 prairies, mountains and valleys, dry lands and swamps or water, al- 

 ternate with each other. A river passing through a forest, a swamp 

 bordered with large trees, or an inundated part of a forest, always 

 collects great multitudes and varieties of birds ; for where the pro- 

 ductions of land and water are combined, the greater the variety 

 and richness of the food. As the supply of food attracts birds to 

 certain localities, so the want of it compels them to abandon others. 

 They manifest great sagacity in selecting the best portions of cer- 

 tain districts. They pry into every hiding-place, into every crack, 

 cranny, and hole, and pick up every digestible thing. 



Trades of Birds. — Considering the different modes in which 

 birds support life, it may be said that they have different trades or 

 callings. Some, like Pigeons, and other granivorous birds, pick up 

 the grains they find on the surface of the ground ; others of the 

 same kind strip the husks from the grain, and some scratch seeds 

 and roots out of the ground. Fruit-eaters pluck fruits with their 

 beaks; insect-eaters seize their prey on the ground, or on the 

 leaves or branches of trees. Some of these latter birds labor very 

 hard for a living, searching with their tongues for insects in the in- 

 nermost recesses of their lurking-places. Ravens pursue all these 

 various trades, and operate on a small scale as regular robbers. 

 Falcons and Hawks, or Eagles, are constant hunters. Vultures 

 are scavengers, and other birds may be regarded as beggars and 

 spongers. 



Aquatic birds have their trades as well as land birds. Many of 

 the former pick their food lying in plain sight ; others ransack the 

 hiding-places of other animals ; some are omnivorous ; others car- 

 nivorous ; some draw their food out of turbid water or soft mud ; 

 others obtain theirs by diving deep in the water, and others, per- 

 ceiving their food from a great height, dart thence upon their prey. 



Genesis and Development. 



The Egg. — After impregnation of the female bird, one of the 

 little yelk bodies which adhere in the ovaries, starts out from the 

 rest, absorbs from the blood all the matter pertaining to the yelk, 

 and is finally itself transformed into a yelk, growing to its proper 

 size. Detaching itself, it slides into the ovi-director, which shows, 

 during the time of laying, an increased activity, and secretes albu- 

 men. Both the yelk and albumen are now pushed forward by the 

 contractions of the ovi-director, and arrive finally at the lower ex- 

 pansion of the same, or the so-called womb (uterus). Here they 

 assume the regular egg form, and receive the shell skin and the 

 calcareous shell. The latter is at first soft and adhesive, but soon 

 hardens, and the egg is complete. By the contraction of the fibers 

 of the muscles of the uterus, the egg is pushed forward into the 

 cloaca, where it is probably colored, and whence it is finally ejected. 

 The size and form of the egg, which may depend on the form of 

 the uterus, vary greatly. There is supposed to be, in general, a 

 certain ratio between the size of the egg and ol the body produc- 

 ing it : but there are large birds that lay comparatively small eggs, 

 and small birds that lay comparatively large eggs. The form of 

 the bird's egg usually resembles that of the hen's egg ; but some 

 birds' eggs correspond more to the form of a top or pear, while 

 others are equally rounded at both ends and are very oblong in 

 shape. Eggs laid in hollows or crevices are generally white, or 

 have only one color; those laid in open nests are, for the most 

 part, speckled. The number of eggs laid by one bird varies from 

 one to twenty-four, provided none are taken from the nest during 

 the process ot laying, as in that case the number may be increased 

 ten or more. But the great majority of birds lay from four to six 

 eggs. 



