Mr. J. BlackwalFs Ornithological Notes. 21 



some natural obstruction in singing birds while they are mute, 

 and that when this is removed the song recommences, is new 

 and bold. I wish you could discover some good grounds for this 

 suspicion." 



More than twenty-six years have elapsed since my attention 

 was first particularly directed to this interesting subject, and I 

 am inclined to believe that if the candid and intelligent natural 

 historian of Selborne had been made acquainted with the re- 

 markable facts which then presented themselves to my observa- 

 tion, he would have ceased to view the suggestion of Mr. Bar- 

 rington merely in the light of a plausible hypothesis*. 



It is a matter of general notoriety that very few of our feathered 

 songsters, in a state of liberty, continue their delightful warbling 

 beyond the end of July, or the beginning of August, the latter, 

 as Mr. White has remarked, being "the most mute month the 

 spring, summer and autumn through ;" but whether this silence 

 is constrained or voluntary can only be determined by a careful 

 examination of the evidence bearing upon the case. 



Ornithologists almost universally attribute the singing of birds 

 to the excitement induced by the passion of love, regarding it as 

 an act of volition, which, without any absolute necessity, ceases 

 to be practised when the predisposing stimulus is no longer felt ; 

 but it cannot be denied that the songs of many species may fre- 

 quently be heard after they have done breeding, and that the 

 woodlark, redbreast, wren and dipper sing even during frosty 

 weather in winter when the sun shines brightly. Besides, per- 

 sons who have the management of birds in captivity are well- 

 aware that they continue to exert their musical powers much 

 longer than birds at large, and that those powers may be cir- 

 cumscribed, or called into full activity at pleasure by regulating 

 their supply of food and the temperature of their domicile; 

 female birds also, when in high condition, are known, occasion- 

 ally, to assume a song somewhat resembling that of the male. 

 These circumstances, together with the early age at which young 

 birds begin to practise their songs, and the facility with which 

 some species may be taught in confinement to substitute an ar- 

 tificial tune for their natural notes, have led me to suppose that 

 a partial coincidence in the periods during which birds of song 

 exercise their reproductive and musical functions may have been 

 mistaken by ornithologists for a relation of cause and effect. 



From observations and experiments made with the greatest 

 care on several species of British singing birds, I have no hesi- 

 tation in asserting that the song peculiar to each is the result of 



* See the Memoirs of the Literary and Philosophical Society of Man- 

 chester, second series, vol. iv. pp. 312; notcf, 465, 466, and vol. v. p. 261. 



