CHAKACTEEISTICS OF BIRDS. 123 



knows who has played with a fowl's drum-stick, pulling 

 upon this tendon. Now this tendon can be pulled upon 

 in the living animal, and the toes of course be bent, with- 

 out any action of the muscle. For observe, that at first 

 the tendon is on the front of the limb, but it passes to 

 the rear before it comes to the heel-bone. The effect of 

 this arrangement is, that when the bird settles down in 

 perching, the bending of the limb pulls on the tendon, 

 and so the toes firmly grasp the perch. This arrange- 

 ment is also of service to birds of prey in securing their 

 victims ; for, when they have pounced upon them, by 

 merely settling down with all their weight, the bent 

 claws grasp them with great force. 



209. There is very great variety in the plumage of 

 birds, the gayest colors appearing in those of tropical 

 climates ; while, on the other hand, the birds of Arctic 

 regions exhibit none but the duller hues. The latter, 

 how r ever, have a much larger proportion of downy feath- 

 ers to keep them warm in the midst of the severe cold. 

 With the bright and splendid colors of the tropical birds 

 there is no power of song, the voice being either absent 

 or disagreeable ; but in the temperate zone, while the 

 plumage is ordinarily much less beautiful, there is great 

 variety of song, especially in the small birds. 



210. The tail is of service in flight, being moved in 

 one way and another, so as to regulate the course of the 

 bird. But it is not its only use to serve as a rudder ; it 

 is a part of the ornament which the Creator has given 

 to this class of animals. Accordingly, it is varied much 

 in its shape, arrangement, and color; and in some cases 

 beauty seems to be aimed at rather than actual service, 

 as in the tails of Peacocks and Birds of Paradise. 



211. The instinct which leads so many kinds of birds 

 to change their climate according to the season is a won- 

 der and a mystery. In a temperate climate there is a 

 multitude of birds in gardens, fields, and forests in the 

 summer, which for the most part disappear as the cold 



