66 GEOTHLYFJS TltlGIIAS. 



HABITS. 



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

 they are at a distance, by their motions. Some are full of nervous activity, while others are more 

 deliberate in their movements. A few closely resemble one another in their evolutions when 

 among the trees, but no one who has ever studied their habits will fail to recognize the Blue 

 Yellow-backs at a glance ; for none of the Sylvicolidre 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 tinds them skipping nimbly from bough to bough, 

 until they perch 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 

 constantly 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 the state they frequent the hummocks 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 deciduous woods. A few remain in Southern New 

 England to breed, but the majority spend the summer in the more northern sections, whore 

 they build their pensile nests amid the long, gray moss, which 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 with energy and an accent so peculiar as to distinguish them at once 

 from those of all other Warblers. The males continue to sing until August, after which 

 various families, composed of parents and young, congregate in small flocks; then, in early 

 September, join the other little birds in their southern migrations. 



GENUS V. GEOTHLYPIS. THE GROUND WARBLERS. 



GEN. CH. Bill, shorter than the head and rather stout. Wings, short. Feet, large. Tarsus, longer than the hind 

 toe and claw. Coracoid bones, slightly exceeding in length the top of the keel, which is low, not being higher than one-half 

 the width of sternum. Marginal indentations quite deep. 



The sternum of this genus at once distinguishes it from all other members of the Sylmcolidae, inasmuch as it 

 is produced forward in a degree quite remarkable ; the coracoid bones are longer and proportionately stouter than 

 any other member of the family. 



GEOTHLYPIS TRICHAS. 



Maryland Yellow-throat Warbler. 



Geothlypis trichas CAB., Mns. Hein., 1850, 16. 



DESCRIPTION. 



Form, robust. Size, not small. Bill, stout, not acuminate. Tail, long and well rounded. Sternum, stoutly 

 built. Tongue, thin, horny, with the edges straight, not acuminate; bifid, the tips fringed with cilia which extend 

 along the sides for about one-third of the terminal length, but become shorter near the base. 



COLOR. Adult male. Above, olivaceous-green, becoming brownish on the top of the head. Wings and tail 

 brown, edged with the same color as the back. A broad frontal band, extending over the eye and on the head, black, 

 preceded above by a whitish margin. Throat, breast, bend of wing and under tail coverts, bright yellow. 

 Abdomen and under wing coverts paler. Sides and flanks olivaceous. There is no change of plumage in autumn 

 excepting that the bill, which in spring is entirely dark brown, then becomes lighter on the lower mandible. 



Young male differs in being duller and lacking the whitish margin to the black mask, which is almost entirely 

 obscured by a rufous suffusion on the forehead and is washed with whitish on the side of the head. 



Adult female is without the black mask and with the yellowish beneath quite dull. 



The young female has a suffusion of rufous on the sides of the head, and the colors are very dull and undecided. 



