NIDIFICATION. 25 



pieces of wood, that one would scarcely believe they could be 

 carried by a bird, if he were not aware of the extraordinary 

 strength of their muscles ; they are so arranged as not to yield 

 readily to the force of the wind, and they support boughs which 

 are bound to each other by the remains of food and of excre- 

 ment, forming a solid habitation bearing the name of eyry. 

 Those species that, in the construction of their nests, only 

 employ rushes and reeds, accumulate them in such quantities, and 

 fix them so firmly to the platform that rains or storms seldom 

 cause their destruction. 



7. Most birds build their nests, in the bifurcation of the branches 

 of tre^s ; in this case, bits of straw and small pieces of wood, 

 carried in the beak, tied and interlaced by means of this, organ, 

 and the aid of the foot, constitute the external frame, which sup- 

 ports the moss and down that form the bed. Some species have 

 the habit of suspending their nest, which is wrought in a still 

 more artist-like manner, to the extremity of a flexible twig, so 

 that, in obedience to every impulse of the winds, this cradle 

 and the sitting bird that inhabits it, experience an almost con- 

 tinued rocking. 



8. Certain nests present, in their structure, a perfect masonry 

 made of little sticks, gravel, or small leaves impregnated with 

 mortar, formed of earth softened with the salivary humor of the 

 bird, or simply mixed with it. How much toil and how frequent 

 must be the goings and comings for the completion of this 

 work! And, when we remember that the bird has, for the 

 execution of its task, but a single instrument, which also serves 

 for the transportation of the materials, we cannot withhold the 

 admiration which is so justly merited. The form of these mortar- 

 built nests, is ordinarily either spherical, conical, or elliptical ; they 

 are established in the angles of windows, of chimnies, of walls, 

 and often on the tables of sheltered rocks. They are either 

 isolated or placed one against the other ; the entrance is made 

 either on the top, or in one side, and sometimes in the lower part. 

 Frequently we find in these structures several compartments ; 

 sometimes a sort of vestibule is separated from the true nest, by a 

 partition, and it is into this apartment that the male retires, after 

 he has carried the necessary food to his sitting female companion. 



7. What is the situation usually selected by the majority of birds for build- 

 ing their nests ? 



8. What instruments are used by birds in the construction of their nests? 

 What is the form of those nests that are put together, like mason work, with 

 a species of mortar ? Do nests ever contain more than one apartment ? 



