Page:The Zoologist, 4th series, vol 5 (1901).djvu/240

216 where I found many birds full of voice, but not the Thrushes. On the 21st, however, with the temperature 45°, and a feeling of spring in the air, there was a general awakening, and this continued till the 29th, when another spell of cold began, and, in spite of one or two fine days, silence prevailed. On February 4th (therm. 28°), a cold but still day, they sang again freely; and from this time onward may be said to have continued in song, with occasional interruptions, but never in the same numbers, or with the same noisy vociferation, as in the autumn.

The conclusions to be drawn from these observations are not altogether clear to me; but I may venture upon a few remarks on them.

First, as to the general conditions of voicefulness, I think it may be safely said that you will not hear the Song-Thrush in strong wind, nor snow, cold fog, or other uncomfortable wintry weather. What really spurs them to sing is still, open weather, when food is easy to get at: sunshine is not a necessity, and the temperature is of no great account until it becomes really low, and continues so for some days. For example, on March 25th, when I was writing these notes, a bitterly cold day of snowstorms, a Thrush was singing finely at 6.45 p.m., with the thermometer at 26°.

Secondly, as regards the meaning of winter song, and its possible connection with breeding, the entire silence of this species between January 3rd and January 21st might suggest a distinction between a winter song, stimulated only by the enjoyment of food and bodily comfort, and the true spring or breeding song. I do not, however, feel by any means sure that such a distinction is to be drawn, without modification; I am inclined to think that the great outbreak of song in the autumn was, in the case of mature birds at least, a forecast of the coming breeding-season. This species is an early breeder, and eggs have been found as early as February 28th : and the silence in January might have been accidental, or have occurred at another time, according to the weather, just as it may also sometimes be noticed in April or May. Birds that have already lived through one or more breeding-seasons must, I should imagine, have come to associate the full vocal powers they have acquired with the joys