68 YELLOW WARBLER. 



resembles the summer song of the Chestnut-sided, which con- 

 sists of a number of rather energetically given notes termi- 

 nating with a warble, and is very much like the ordinary song 

 of the Nashville Warbler. But both Yellow and Chestnut- 

 sided give a more feeble song in July; the result of the weak- 

 ening of the muscles of the syrinx, as explained on pages 43 

 and 44. As might be anticipated from the great similarity 

 of the songs, the syrinx and its accompanying vocal muscles, 

 are quite similar in both birds. In Fig. 36, f, may be seen a 

 cut of the syrinx and bronchial tube of the Yellow Warbler, 

 somewhat enlarged, w, is the windpipe ; o, and 11, the syrin- 

 gal muscles fused into one that is divided to allow the inser- 

 tion of the sterno-trachealis, xi ; v, is the bronchial tube. At 

 E, is given a much more enlarged view of the inside of the left 

 bronchial tube. There are eight complete bronchial rings 

 (see V ), leaving space for thiee half rings, which enclose a 

 very short vibrating tympaniform membrane (seeT). Short 

 as this membrane is, it and its fellow on the opposite tube 

 produce most of the sounds which this warbler is capable of 

 uttering, for the other vibrating membrane, the semiluna, is 

 poorly developed. The Yellow Warbler, in addition to the 

 song, gives quite a sharp note of alarm. 



Migration and Breeding Rangk. The Yellow War- 

 l:)ler breeds commonly from the Carolinas northward, at least 

 as far as Massachusetts, and less commonly, being restricted 

 to the open sections, as far as the Arctic regions. It migrates 

 south early, the majority leaving Massachusetts the first week 

 in September, but a few, probably migrants from further north, 

 may be found later. It winters in Central America and North- 

 ern South America. I procured a single specimen on Cay- 

 man Brae, April 22, 1888, but this was evidently a straggler 

 as I did not se? any more, nor have I ever seen it in any other 

 of the West Indies, in the Bahamas, or in Florida. It arrives 

 in Massachusetts the first week in May. 



