58U BLUE YELLOW-BACKED WARBLER. 



to the adult female. The young female has the yellow beneath less extender! and withmit a trace of che.st- 

 nut. There is also but a slight indication of tlic yellow patch above. In all stages the irides are brown ; 

 upper mandible, brown ; lower, whitish ; feet, brown. 



OBSERVATIONS. 



This pretty little species may be distinguished at once from all others by the ever present yellowish 

 green patch upon tlie back, combined with yellow throat. Distributed during the breeding season through- 

 out Eastern United States from Virginia north to Canada, west to the Rocky Mountains ; winters in Mexico, 

 Central America, Bahamas, West Indies and Key West. 



DIMENSIONS. 



Average measurements of twenty-three specimens. Length, 4.7:") ; stretch, 7.30 ; wing, 2.30; tail, 1.70 

 bill, .40 ; tarsus, M. Longest specimen, 4.1)0 ; greatest extent of wings, 7.70 ; longest wing. iMS.") ; tail, l.S.~) ; 

 bill, .49 ; tarsus. .7r). Shortest specimen, 4.25 ; shortest extent of wings, 7.70; shortest wing, 2.20; tail, 

 1.40; bill, .3.j; tarsus, .59. 



DESCRIPTION OF NESTS AND EGGS. 



Nests placed in trees composed of the drooping sprays of the long gray moss, wliich arc lonpeil up often 

 into purse shaped nests, having a hole in the side, or other specimens are hammock shaped and open at the tojx 

 All that I have seen were constructed wholly of the moss. Eghs three or four in number, jnire white in col- 

 or, spotted and dotted everywhere with light reddish-brown and lilac, but more sparsely at the smaller end. 

 Dimensions from .G6 by .48 to .70 by .50. 



HABITS. 



A careful observer of birds can readily deteriniiie each species of the Warblers, even 

 wlien they are at a distance, by their niotit)ns. Some are full of nervous activity, while 

 others are more deliberate in their movements. A few closely resemble one another in 

 their evolutions among the trees, but no one who has ever studied tlieir habits will fail 

 to recognize the Blue Yellow-backs at a glance ; for none of the Sylvicolidae conduct 

 themselves .so peculiarly. They sometimes glide along the limbs like Creepers or cling 

 to the under surface of the bark after the manner of Nuthatches ; but the next instant 

 finds them skipping nimbly from bough to bough, until they jjerch on the topmost twig, 

 from which they dart into air to secure some rapidly moving insect. Thus they are ever 

 changing position and there are but few species which so ct)nstantly assume so many 

 varying and graceful attitudes. 



These birds are found in Florida throughout the winter but most abundantly in 

 spring, when the great avian waves sweep northward. While in this state they frequent 

 the hammocks, but more generally avoid the piny woods. They arrive in Massachusetts 

 during the latter part of May, when they are found among apple trees, and in deciduou.s 

 woods. A few remain in Southern New England to breed, but the majority spend tiie 

 summer in the more northern sections, where they build their jiensile nests amid the long, 

 gray moss, wdiich so plentifully drapes the trees in these wilds. The song of the Blue 

 Yellow-backed Warbler consists of a few simple, lisping notes, yet they are given witli 

 energy and an accent so peculiar as to distinguish them at once from those of nil other 

 Warblers. The males continue to sing until August, after which vnrious families, com- 

 posed of parents and young, congregate in small tiocks ; then in early September, join the 



