MANIFESTED IN THE ANIMAL KINGDOM 87 



lived to the age of nearly one hundred years, and adds : 

 " yet they breed so rarely, though many have been kept 

 in Europe, that the event has been thought worth record- 

 ing even in the gravest publications." 1 



The difference between the life of a wild parrot and 

 that of a parrot in confinement amounts to this, that 

 when wild the birds lead an active life in searching for 

 their food and playing about among the branches of 

 the trees, and the food will consist mostly of berries and 

 fruits of various kinds, bulky and poor in proteids. In 

 confinement they lead a life of comparative inactivity 

 and are highly fed on foods rich in proteids. A consider- 

 able measure of sterility, therefore, is to be expected under 

 confinement. 



In this case, as in others, we should expect that when 

 given a larger measure of liberty they would prove more 

 fertile. And we are told that " when Mr. Burton turned 

 out a large number of parrots in Norfolk, three pairs 

 bred and reared ten young birds in the course of two 

 seasons ; and this success may be attributed to their 

 free life." 2 Apparently the birds were regularly fed in 

 this case. Had it been possible for them to have picked 

 up their own living, the results would probably have been 

 greater. 



The parrot is a long-lived, slow-breeding bird of high 

 cerebral development, as its well-known intelligence 

 shows. Now, we should expect to find that confinement 

 has an effect corresponding to the measure of normal 

 fertility. A very fertile type would have its fertility 

 impaired but not wholly destroyed by captivity ; while 

 a relatively infertile type would become almost completely 

 sterile. Thus we can understand the almost complete 



1 Variation oj Animals and Plants under Domestication , chap, zviii. 

 1 Ibid. 



