202 BIRDS OF THE REPUBLIC OF PANAMA — PART 2 



to texensis, and smaller, grayer ones to micromeris, the latter being 

 regarded as migratory in spite of its accepted breeding range from 

 southern Mexico southward. This comfortable method of disposal 

 ended when in late June 1953, with Eugene Eisenmann as companion, 

 I collected a small series in the savanna area of the western part of 

 the Province of Panama. Those taken, which included young barely 

 grown, were small and dark in color and so did not fit the pattern. As 

 more of this type came to hand it became obvious that there was a 

 breeding population in Panama. This information has required a 

 review that in brief summary may be stated as follows. Birds of the 

 north to which the name texensis applies are whitish or very pale buff 

 on lower breast, sides, and abdomen, with the rather indefinitely out- 

 lined band across the upper breast lighter gray. Above they show the 

 usual variation from gray to blackish, with lighter markings pale buff 

 to grayish white. They vary considerably in size, as indicated in 

 length of wing and tail. According to present understanding this 

 group breeds from central California and Texas to central Michoacan 

 and southern Veracruz. It is migratory from the area north of central 

 Mexico, and then ranges through Central America and Panama to 

 northwestern Colombia. 



The typical form Chordeiles a. acutipennis is the breeding bird in 

 South America from northern Colombia (except in the upper Mag- 

 dalena Valley where another race, crissalis Miller, is recognized), 

 northern Venezuela, Trinidad, and Tobago south, east of the Andes, 

 to northern Bolivia and southeastern Brazil. This is definitely smaller 

 and is darker, blacker above in ground color, with the lighter markings 

 paler, from grayish white to buff much as in texensis. The wing bar 

 in some (not in all), and the tail bar in some of the males is narrower. 

 On the under surface the lower foreneck is darker buff. 



On first examination breeding specimens from Panama may seem 

 to be like typical acutipennis as they are dark in back and crown color. 

 The lighter markings of the dorsal surface, however, are definitely 

 deeper buff, and wing and tail bars are more variable in width. The 

 size also averages somewhat larger. Actually they agree in size and 

 color with the birds of more northern Central America recognized 

 under the name C. a. micromeris. This then has a breeding range 

 extending from southern Mexico through the whole of Central Amer- 

 ica. It comprises an intermediate population both in size and color 

 between the principal group of South America as at present recognized 

 and texensis of the north. 



The group as a whole offers difficulty in the assignment of some 



