THE REASON WHY IN NATURAL HISTORY. 



493 



the ostrich, because of the amount of water the 

 down would absorb. 



41. Why does a black down grow under the 

 feathers of birds as winter approaches t 



Because the down is a non-conductor of heat, 

 and black the warmest color. It is therefore 

 best adapted to keep in their bodily warmth dur- 

 ing the cold of winter. 



42. Why have birds hard beaks t 



Because, having no teeth, the beak enables 

 them to seize, hold, and divide their food. 



43. Why are the beaks of birds generally long 

 and sharp t 



Because the greater number of birds live by 

 picking up small objects, such as worms, insects, 

 seeds, etc. The sharp beak, therefore, serves as 

 a fine pincers, enabling them to take hold of 

 their food conveniently. 



44. Why have snipes and woodcocks long tapering 

 bills t 



Because they live upon worms which they find 

 in the soft mud of streams and marshy places ; 

 their long bills, therefore, enable them to dig 

 down into the mud after their prey. 



45. Why have woodcocks, snipes t etc. , nerves run- 

 ning down to the extremities of their bills ? 



Because, as they dig for their prey in the soft 

 sand and mud, they cannot see the worms upon 

 which they live. Nerves are therefore distrib- 

 uted to the very point of their bills (where, in 

 other birds, nerves are entirely absent) to enable 

 them to prehend their food. 



46. Why have ducks and geese square-pointed 

 bills t 



Because they not only feed by dabbling in soft 

 and muddy soil, but they consume a considerable 

 quantity of green food, and their square bills en- 

 able them to crop off the blades of grass. 



47. Why has the spoon-bill a long expanded bill 

 lined internally with sharp muscular points t 



Because the bird lives by suction, dipping its 

 broad bill in search of aquatic worms, mollusks, 

 insects and the roots of weeds. The bill forms 

 a natural spoon, and the muscular points enable 

 the bird to filter the mud, and to retain the 

 nourishment which it finds. 



48. Why has the spoon-bill long legs t 

 Because it wades in marshy places to find its 



food. Its legs are therefore long, for the pur- 



pose of keeping its body out of the water, and 

 above the smaller aquatic plants, while it 

 searches for its prey. 



49. Why have the parrots, etc., crooked and 

 hard bills t 



Because they live upon nuts, the stones of 

 fruit, and hard seeds. The shape of the bill, 

 therefore, enables them to hold the nut or seed 

 firmly, and the sharp point enables them to split 

 or remove the husks. 



50. Why can a parrot move its upper as well at 

 its lower bill t 



Because by that means it is enabled to bring 

 the nut or seed nearer the fulcrum, or joint of th 

 jaw. It therefore acquires greater power, just 

 as with a pair of nut-crackers we obtain in- 

 creased power by setting the nut near to the 

 joint. 



51. Why are the bones of birds hollow t 

 Because they are thereby rendered lighter, 



and do not interfere with the flight of the bird 

 as they would do if they were solid. Greater 

 strength is also obtained by the cylindrical form 

 of the bone, and a larger surface afforded for the 

 attachment of powerful muscles. 



52. Why do all birds lay eggs 9 



Because, to bear their young in any other 

 manner, would encumber the body, and mater- 

 ially interfere with their powers of flight. 



As soon as an egg becomes large and heavy enough to be 

 cumbersome to the bird, it is removed from the body A 

 shell, impervious to air, protects the germ of life within, 

 until from two to twenty eggs have accumulated, and then, 

 although laid at different intervals, their incubation com- 

 mences together, and the young birds are hatched at the 

 same time. 



53. Why have birds with long legs short tails / 

 Because the tails of birds are used to guide 



them through the air, by a kind of steerage. 

 When birds with long legs take to flight, they 

 throw their legs behind, and they then serve the 

 same purpose as a tail. 



54. Why have birds that sv ''m u^n water wck- 

 feet t 



Because the spreading out of the toes of the 

 bird brings the membrane between the toes into 

 the form of a fin, or water-wing, by striking 

 which against the water the bird propels itself 

 along. 



55. Why have birds that swim and dive sktrt 

 legst 



