368 BRITISH BIRDS. 



suppose that they had not sufficient food during- the 

 slightly less mild period preceding this. 



Then again, different species are differently affected by 

 weather conditions other than temperature. Skylarks, for 

 example, sing in frosty weather in the early days of their 

 song-period if the sun is shining ; while most species (and 

 in our experience the Mistle-Thrush is no exception) dislike 

 strong wind ; Blackbirds, after their normal song-period 

 is over, are most likely to sing during heavy showers — 

 this has been attributed to an expectation of increased 

 food supply ; Hedge-Sj)arrows sing more than other 

 species in drizzling or misty weather; while late snows, 

 with the ground unfrozen, completely stop Thrushes and 

 Chaffinches, and partially stop Robins and Hedge- 

 Sparrows, but have little effect on Mistle-Thrushes and 

 Skylarks. 



Several species have an autunni, as well as a spring 

 song-period. This is well seen in the Skylark, Pied 

 Wagtail, Creeper, Goldcrest, Chiffchaff and Willow- 

 Wren ; less so in the Mistle-Thrush, Blackbird, Chaffinch 

 and Lesser Whitethroat. The Swallow sings all through 

 the summer, the Thrush, Robin and Hedge-Sparrow sing- 

 all tlirough the winter, and the Wren makes no appreciable 

 break either in winter or late summer. 



Tt has often been suggested that autumn singing is that 

 of birds of the year. This is certainly not the case with 

 many individual birds well known to us, which sing on the 

 same branches in autumn as in spring, and from these 

 observations it may be concluded that in general autumn 

 song comes from the adult birds. Where the young are 

 markedly different from the old birds, it is easier to decide 

 the point. We have watched young Robins carefully, but 

 have not found them singing ; on the other hand we have 

 observed a young Pied Wagtail and also what appeared to 

 be a young Willow- Wren singing in the autumn. 



Most sj)ecies sing every day during their regular song- 

 periods, but the Marsh-Tit, Pied Wagtail, Reed-Bunting, 

 Red-backed Shrike, Martin, and the Sand-Martin only 



