^VARBI.EK SONCS li 



birds will be in song all day long. But it must be renienil^ered 

 that some species do not follow any rule about their singing, 

 and that with the majority of the species we know little about 

 them except as they pass us on their way to the north. It 

 may well be that the all night journey, as they migrate, makes 

 the noon-day sleep necessarj-, while at their breeding grounds 

 they have little need for that rest and so sing all day. But 

 with many of the species which remain with us to nest there 

 is the noon-day resting time all the season. 



SEASONAL. 



There are seasonal song periods as well as diurnal. These 

 will be spoken of in the discussion of the several species, .so 

 that I need only discu.ss here the general subject. 



Most male Warblers sing more or less during their north- 

 ward journey, and until the care of the young leaves no time 

 for song. Singing begins at least as soon as the northward 

 journey begins, reaches its height while the mate is brooding 

 over the eggs, then gradually declines as the cares of the fam- 

 ih^ increase, ceasing entireh' with the beginning of the molt 

 which follows clo.sely the complete development of the young 

 into independent foragers. After the plumage has been re- 

 newed, some species have a short song period before leaving 

 for the south again. It is difficult to say how large a number 

 thus renew their .song, but the writer's list includes twelve 

 species positively identified, with several others about which 

 there may be .some doubt. It is more than likely that a far 

 larger number sing at some time during the autumn months, 

 either regularly or occasionally. Few songs will be heard, 

 during this second song period, except in the early morning 

 hours under favorable conditions. With .some species the sec- 

 ond song period is marked by a .somewhat different .song, and 

 with many by a weaker one. 



It is suggestive that the species which are known to sing 

 during autumn are those whose color patterns are practically- 

 the same at all seasons, or at least not markedly different in 

 fall from the spring dress. The spring song period is accom- 

 panied by enlargement of the reproductive organs, but the re- 

 sumption of song in the fall is rarely so accompanied. It is 

 not likely that all individuals of a species which has a second 



