Mr. J. Blackwall’s 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 tue 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 1s 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, note ¢, 465, 466, and vol. v. p. 261. 
