454 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



to early December, and dates in the spring period somewhat earher 

 in March and later in May. There are no certain reports for the 

 intervening "winter" months. 



That the Eastern Wood Pewee is the most abundant of the two 

 groups in Panama is evident from the specimen records assembled 

 in the course of my personal field work, where 26 of the 33 migrant 

 Wood Pewees obtained are the present bird against 7 of the western 

 group ( listed under sordidithis and its races ) . 



These northern migrants in Panama are found especially in low- 

 land and foothill localities, ranging in the borders of woodland and 

 in scattered trees and shrubs in open areas. Eisenmann, who has had 

 extensive experience with them, reports that though many remain 

 silent some call at intervals, with notes that readily identify them as 

 the eastern bird. They seek high, open perches, fly out to capture 

 passing insects, and then usually circle gracefully to return to the 

 lookout point. In this they behave as they do on their nesting grounds 

 in the North. Those that I have collected in April in northward 

 passage have been very fat. 



While the migrant wood pewees as a whole are closely similar, they 

 are separable into two groups, one eastern and one western, in their 

 distribution in the breeding season. Those of the east (long known as 

 virens) have the lower half of the bill (the mandible) pale white or 

 huffy white, except for the narrowed point at the tip. The breast 

 band is paler gray, often partly, sometimes wholly, divided in the 

 center ; lower breast and abdomen faintly yellowish white varying to 

 very pale yellow ; axillars and under wing coverts lighter in color, 

 white to grayish brown tipped and edged with white. The gray of 

 the dorsal surface in unworn condition has a faint greenish cast in its 

 generally grayish olive hue. In the breeding season their range ex- 

 tends through eastern North America from southern Manitoba, 

 Ontario, and Quebec to southeastern Texas, the Gulf Coast and 

 central Elorida. Through this extensive area they are uniform in 

 color and size without appreciable variation. 



The western bird, Contopus sordidulus, and its allied subspecies 

 have the distal end (in some the greater part) of the mandible brown 

 or blackish brown. Above and on the breast the widespread northern 

 populations are much darker, being blackish brown to darker gray ; 

 southern birds, in Baja California and Guerrero, although pale, are 

 gray with no greenish cast. These birds in their summer homes range 

 from eastern Alaska and southern Yukon through western United 

 States southward to Central America. All are migratory and winter 



