BIRD. 



89!) 



though birds of long and powerful flight when hungry, 

 they are so reluctant to take the wing after feeding, 

 that they may be knocked down with a stick, or taken 

 with the hands, without making much resistance. 



Their power of enduring hunger seems to be in 

 proportion to that of taking food directly into the 

 stomach, and converting it into nourishment by a more 

 simple apparatus ; and, unless when they are forced 

 from their retreats by hunger, they are far more 

 retired and quiet than the vegetable feeders. The 

 same analogy holds between the carnivorous and 

 the herbivorous mammalia, the former come abroad 

 only at particular times, the latter are habitually upon 

 their pastures, and their hunger begins when the 

 receiving stomach is empty, or nearly so. 



Birds which are exclusively vegetable in their 

 feeding, and those which are exclusively carnivo- 

 rous, may be regarded as the extremes of the class, in 

 so far as the alimentary system is concerned. The 

 former have that system largest, most complicated, 

 and most constantly in action, and the true stomach 

 always a gizzard. The latter have, in proportion to 

 the general size of their bodies, the alimentary appa- 

 ratus smallest, and also the most simple, acting readily, 

 but acting, or requiring to act, only at intervals ; and 

 they have the stomach always membranous. 



Those vegetable feeders that live much on seeds 

 and in temperate climates which is the case with the 

 majority, require an auxiliary to even the muscular 

 action of the most powerful gizzard, in order so to 

 grind and divide the food as that the gastric juice 

 can act upon it. For this purpose they swallow small 

 stones and gravel ; and it has been observed that 

 some of the gallinaceous birds were kept in equal 

 condition and in better health upon much less food 

 when they had access to those auxiliaries. It is not 

 improbable that a small quantity of resisting matter 

 may help the digestion of all stomachs ; and that it is 

 upon this principle that brown bread is more diges- 

 tive by the human stomach than bread of the finest 

 flour from which the whole of the husky matter is 

 separated. 



Intermediate between those two extreme forms of 

 the digestive system in birds, there are many mo- 

 difications, adapted to all varieties of food. Some 

 of them have the stomach more membranous toward 

 the one extremity, and more muscular toward the 

 other ; in some the character of the stomach is par- 

 tially changed by long continuance on a different 

 kind of food ; and it is by no means improbable that, 

 in some of those species which live in great part upon 

 insects at one season of the year, and chiefly upon 

 vegetable substances at another, the stomach may 

 undergo seasonal changes. 



In proportion as any animal, whether bird or not, 

 is more vegetable in its feeding, its abdomen, in a 

 natural and healthy state, is always the more bulky in 

 proportion to the whole body. This is very conspi- 

 cuous in the mammalia, (in which the size and distinc- 

 tions are more easily seen,) in which all the grazing 

 tribes are full, and all the carnivorous ones lank in the 

 belly ; but it holds also in birds, though in them it is 

 less conspicuous, as the whole body is covered with 

 feathers, and the several parts are not so easily dis- 

 tinguished from each other. If, however, we attend 

 carefully to the outline of their forms, we may, in most 

 cases, discover a greater uniformity of thickness 

 throughout in the vegetable feeders. This appears 

 not only in the larger birds, in which the difference of 



other habits may be supposed to have some effect, but 

 even in the small birds. 



Generally speaking, too, vegetable feeding birds 

 are not so well winged as those which feed upon 

 animal matters. All the gallinaceous birds are heavy, 

 comparatively bad fliers, and take only very low and 

 short flights ; while the birds of prey are among the 

 most powerful fliers in the whole class ; though even 

 these are perhaps not so constantly on the wing, or 

 so very long flighted, as some of the tribes which feed 

 chiefly upon insects. In accordance with this forma- 

 tion, the vegetable feeders are not so regularly 

 migratory. Some of them, indeed, change their 

 abodes to considerable distances within the same 

 countries ; but they do not so frequently cross the 

 seas, or range so far in latitude in their migrations. 



The vegetable feeders and the animal feeders, 

 among the mammalia and birds, agree with each 

 other in the feeding in the two races, and differ from 

 each other in the different feeders of the same race, 

 in other respects. The vegetable feeders are, in 

 almost all the genera, more or less gregarious, both 

 in the one class and in the other ; and when they 

 migrate, they generally migrate in flocks, often in 

 flocks containing immense numbers. The passenger 

 pigeons of America, and also some of those which 

 migrate seasonally in the longitudes of the east side 

 of New Holland, New Guinea, and the Molucca 

 islands, appear in numbers far exceeding those of any 

 migrant birds of other regions or other species ; and 

 some of those which belong to the latter migration 

 are as gay in their plumage as the parrots, or any 

 other of the finest birds of warm climates. The 

 males are also more polygamous among the vege- 

 table feeders ; and it is among them chiefly that 

 they fight battles of gallantry, though many of the 

 omnivorous ones agree with them in these, and also 

 in some other of their characters. 



That increased energy of character, which more 

 or less affects all birds in the pairing season, appears 

 to affect the different feeders in a different manner. 

 Their breeding plumages are much more gay, as 

 compared with the ordinary dress throughout the 

 year, and the naked skin upon the head blooms 

 into more brilliant hues. The eagles and hawks, 

 which are the most carnivorous of the whole race, 

 show the least change, either in colours or in mari- 

 ner, at that season ; but the vultures, in which there 

 is a slight approximation to the gallinaceous charac- 

 ter, and a more decided one to the omnivorous, show 

 a little more seasonal change ; and, though race after 

 race is constantly breaking in and destroying the 

 regularity of the gradation, there is an increase of 

 change till we come to those families which may be 

 said to bloom and fade yearly, something after the 

 manner of plants. 



It is these breakings in of one tribe of birds upon 

 the characters of another, which makes the system- 

 atic arrangement of this class of animals so uncer- 

 tain and difficult ; and the more that we study them, 

 nay, the more intimately and accurately that we 

 become acquainted with them, the less hope have 

 we that any future knowledge can remove the diffi- 

 culties. The four systems of the food, and the three 

 habitats air, land, and water, present themselves in 

 such varied combinations and proportions, that the 

 conclusion which we might very fairly draw from one 

 character is barred by an opposite one, which follows 

 as naturally from another ; so that we cannot have a 



