562 CLASS AVES. • 



the head upon the back. Their sleep is light ; and it is not un- 

 frequent to hear them utter some cries during the night. In 

 a state of domestication, after they go to rest, is said to be the 

 most suitable time for repeating to them such words as they 

 are intended to learn, because they then experience no distrac- 

 tion. 



Their life is very long ; and the mean duration of it, among 

 the parrots, properly so called, is calculated at forty years. 

 Instances, however, have been known, of individuals who lived 

 in a state of domestication ninety, and even a hundred years and 

 more. The parrakeets generally live about five and twenty years. 



One effect of captivity, on some species, according to M. 

 Le Vaillant, is to change the colours of the plumage ; and to 

 this cause he attributes the frequent varieties observable among 

 these birds. Those that are termed tapires, which we have 

 already alluded to, are regarded by M. Virey as natural va- 

 rieties ; bvit he considers them to be produced by a state of 

 weakness, or malady. 



The birds of this genus are monogamous. They make their 

 nests in the trunks of rotten trees, or in the cavities of rocks ; 

 and compose them, in the first case, of the detritus, or dust of 

 the worm-eaten wood, and of dry leaves in the second. The 

 eggs are not numerous ; usually only three or four each time ; 

 but the broods take place several times in the year. The young 

 when born, are totally naked ; and the head is so large, that 

 the body seems to be merely an appendage to it. They re- 

 main sometime without having sufficient strength to move it- 

 They are subsequently covered with down ; but are not com- 

 pletely invested with feathers for two or three months. They 

 remain with their parents till after the first moulting, and then 

 leave them for the purpose of pairing. The eggs are ovoid, 

 short, as thick at one end as the other, and those which are 

 known are of a white colour ; some of them are nearly equal 

 in size to those of a pigeon. 



It was for a long time imagined that these birds could pro- 



