INSTINCTS OF BIRDS. 263 



species, in a state of nature, are instinctive. 

 This I have endeavoured to prove in an essay, 

 read before the Society in 1822, and prmted in 

 the fourth volume of the new series of Memoirs, 

 by shewing, that even such individuals as are 

 brought up in situations where they have no 

 opportunity of being instructed in their appro- 

 priate notes, do, nevertheless, utter them na- 

 turally. 



The pairing of wild birds, and the period at 

 which they prepare to perpetuate their species 

 are determined, according to Dr. Darwin, by 

 the acquired knowledge, that their joint labour 

 is necessary to procure sustenance for a numerous 

 progeny, and that the mild temperature of the 

 atmosphere in spring is suitable for hatching their 

 eggs, and for producing a plentiful supply of 

 that nourishment which is wanted for their 

 young. This opinion he attempts to support 

 by the fact, that poultry which have an abun- 

 dance of food throughout the year, and are pro- 

 tected from the inclemency of the weather, lay 

 then* eggs at any season and never pair. But it 

 should be recollected that this is not the case 

 with pigeons placed under similar circumstances, 

 which do pair, though they produce only two 

 young ones at a time ; and that the pheasant 

 among our naturalized, and the black grouse 



