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the middle of last November I was struck, like many others, by the vociferous singing of Song-Thrushes; they were unusually numerous, and almost every individual seemed to be uttering some kind of song, and continuing it more or less from early morning, when the voicefulness was at its highest point, till sunset, and even later. At the same time it happened that there came into my hands an interesting work on the song of birds by Dr. V. Häcker, of Freiburg-in-Breisgau, in which I found some useful remarks on the autumn and winter singing of birds, which seemed to point to the desirability of further close observation out of doors. I was then living close to the Park at Oxford, and was in the habit of going out daily before breakfast, as well as of crossing the Park two or three times a day on my way to and from college; and I determined to note down each day throughout the winter what birds I heard singing, and especially to record the voicefulness of the Song-Thrush. This I continued to do until the middle of March. My chief object was to ascertain, if possible, whether the great outburst of song which I had noticed was psychologically connected with the breeding season, or should be reckoned by itself as merely the expression of bodily comfort, arising from abundance of food and a mild temperature. I wished to know how long it would go on without interruption—whether there would be any considerable break before the true spring song began, and, if so, how far it would be due to a change of temperature. I did not, as will be seen, arrive at any very definite conclusions, but I hope to be