92 OBSERVATIONS ON BIRDS. 



have attended to the notes of birds, I never remember 

 to have heard it in a single instance in autumn. It 

 is also always later than the thrush in commencing 

 song, after the severe part of the winter is over : it 

 seems to wait for some decided increase of tempera- 

 ture, such as characterizes a fine mild day in the 

 early spring, of the gradual approach of which season 

 its note is a sure harbinger. 



The greenfinch I have, in two different years, 

 heard for a few days in the month of December, but 

 it does not re-assume with any regularity. 



The chiff-chaff, as observed by White,* " chirps 

 till September." The willow warbler also will oc- 

 casionally prolong its note till that month, though 

 the greater number appear to stop about the middle 

 of July, if not sooner. 



The whitethroat is also said by White to 

 "sing on till September." This, however, is cer- 

 tainly not the case here, where I never heard it after 

 July 28th, and the greater number of individuals 

 stop ten days sooner. 



It is probable that, after allowing for errors of ob- 

 servation, it will still be found that the same species 

 of birds, in some instances, have different habits, in 

 respect of their periods of singing, in different locali- 

 ties. It is this circumstance which gives an interest 

 to tables of the above kind, brought together from 

 various stations, and compared with each other. 



Thus, I have myself observed that thrushes and 

 blackbirds, which are seldom heard at Swaffham 



* Called by him the " smallest willow-wren." 



