86 



EXPLORATIONS AND SURVEYS WEST OF 100TH MERIDIAN. 



summer-residence, never allowing the intrusion of the larger birds to 

 pass unnoticed. The loud call-notes of the male are at this season 

 almost incessantly repeated. After watching the actions of several 

 pairs, I felt sure that certain thick, tall fir-trees had been selected as the 

 sites of their nests, but these I was not able to detect, and I do not 

 think that the nest is finished and the eggs deposited much, if any, before 

 the latter part of June. 

 Bill black ; lower mandible light-brown ; legs and feet black. 



G6. Contopus virens (L.), var. richardsonii, Sw. Western Wood-Pewee. 

 The most abundant representative of the family. Inhabits the dark 

 recesses of the pine- woods as well as the edges of clearings and ravines. 

 Unlike the preceding species, which stations itself on the loftiest stubs, 

 this flycatcher pursues its prey among the lower branches of the trees, 

 and often descends almost to the ground to snap up a fly or moth. Its 

 song bears a slight resemblance to that of the eastern pewee (G. virens), 

 but is shorter and much more emphatic. The call-note is entirely differ- 

 ent. A nest kindly presented by Mr. Aiken, and found by him near 

 Fountain, Col., shows but little difference in style and structure 

 when compared with eastern examples. It is composed mostly of 

 sheep's wool, externally covered with bits of bark and leaves, and lined 

 with fine grasses. Its depth, of an inch and a half, is greater than in 

 any I have ever seen in the East, but possibly this may have been ren- 

 dered necessary for the preservation of the eggs, on account of the 

 prevalence of high winds in this locality. 



67. Empldonax pusillus (Sw.) Little. Flycatcher. 



Wherever willows are found growing in small clumps or fringing 

 the streams, this flycatcher is almost certain to be found common, and 

 it is rarely seen in the summer in other situations. Its habits and 

 notes appear to be identical with those of its eastern analogue, irom 

 which it differs mainly in its paler coloration. Its nest is placed in the 

 upright fork of a bush or sapling but a few feet from the ground, and is 

 composed of grasses and fibrous material, rather loosely woven together, 

 and lined with fine grasses. Its general appearance is much like that 



