214 THE ZOOLOGIST. 



But the caution needed in dealing with these negative instances 

 is well shown by the example of the Crossbill. It is common to 

 quote this bird as an example of abnormal habit in the physio- 

 logical sense, since it usually pairs and sings in December and 

 January, breeds in February, and hatches its young in March. 

 Naumann has already pointed out the meaning of this : the bird 

 performs the work of propagation and rearing precisely in the 

 months in which its chief food, the cones of pines, are at their 

 ripest and best, so that the parent birds find it then easiest not 

 only to feed themselves, but to supply their young with the seeds 

 which they convey to them in their crops." 



It will be seen from this passage that Dr. Hacker, like Mr. 

 Aplin, clearly separates the true autumn song, heard after the 

 moult, from the winter song which often begins in November ; 

 and with this conclusion most field ornithologists will probably 

 agree. As to the meaning of the winter song, he is not so clear ; 

 apparently he takes it as in part " voice-play," the result of 

 abundant food and bodily comfort, and as having no immediate 

 connection with breeding, but adds a useful caution suggested by 

 the case of the Crossbill. My observations of last winter, so far 

 as they go, seem to support both his explanation and his warning. 



It was on November 17th, a very uncomfortably chilly day, 

 that I first made a note of the great number of Thrushes in 

 song. No doubt Central and Southern England had been visited 

 by a large immigration from the north and east. It was dull, 

 moist weather, chilly rather than cold, and unusually still. I 

 am convinced, though I cannot prove it, that not only old males, 

 but young birds, and even females, were using their voices to 

 swell the chorus : every bird seemed to be making some sort of 

 noise, and there was every variety of performance, from the full, 

 clear utterance of the practised singer to the harsh and wheezy 

 notes of the novice or the female. As I have already said, this 

 vocal activity continued in full swing, without apparent diminution 

 of the numbers, until December 8th, when I left Oxford for the 

 Christmas vacation, the weather all the time being mild and 

 damp. I did not observe any distinct sign of courting or sexual 

 activity. 



After leaving Oxford, I was at Kingham, in the north-west of 

 the county, until January 18th, and continued my notes there. 



