72 BLUE YEI-LOW-BACK. 



XOKTHERN BLUE YELLOW-BACK. 



Coiiipsotlilypis ainericana nsneae. 



Plate VII, Fig. 1, male; Fig. 2, female. 



Size 4.25 to 4.90. Yellow on throat and upper breast, us- 

 ually with a patch of sepia on the latter; above bluish, with the 

 middle of back greenish yellow. Common during the migra- 

 tions throughout the whole of New England, breeding abund- 

 antly on Cape Cod and in other sections where the lichen 

 known as the old man's beard occurs on the trees. 



Adult Male. Slaty blue above, brightest on the head. Yellow on the 

 throat and breast, with a band on the latter streaked Avith sepia, sometimes mi.\- 

 ed with bluish; remaining lower surface, white. 



Advlt Female. Similar but duller, and the sepia of the breast is not as 

 prominent. 



Young. Somewhat duller than the female, there is less yellow below and 

 often no sepia on breast, and the yellowish patch of the back is sometimes only 

 fauitly indicated. 



Nestlings. Pale slaty -blue above, with no trace of yellow: giayish beneath, 

 slightly tinged with yellow on the throat. 



Dimensions. Length, 4 75 ; stretch, 7.30; wing, 2.30 ; tail, 1.70: bill, 

 .40 ; tarsus, .63. 



Nests and Eggs. Xests, placed in trees, composed of the old man's beard 

 looped into the form of a purse, with the opening on top. Sometimes a little 

 "xass is used as a lining, but usually the nest is composed wholly of the lichen. 

 A f-^'W nests are hammock -shaped. Eggjs, three or four: white, spotted an<l dot- 

 ted everywhere, but rather more thickly on the large end, with reddish brown 

 and lilac. Dimensions, .06 by .48. 



General Habits. Although a large proportion of our 

 warblers have a number of similar habits, careful study will re- 

 veal some minor points of difference which will be found val- 

 uable in distinguishing species. Thus, while we observe that 

 as a rule, the warblers have a rather swift, erratic flight, espec- 

 ially while crossing comparatively narrow spaces, and that all 

 are active, we see that there are some differences in flight, and 

 that there are varying degrees of activity. Few among our 



