Minot on Colorado Birds. 
231 
liquid. It is sometimes prolonged to an attempted warble. Their other 
notes are a liquid chuck and a whistled pheu (wonderfully like a Thrush’s, 
yet akin to the Red-wing’s), a chatter, and quite a liquid trill : also a 
petulant note (?). 
38. Contopus borealis, Baird. Olive-sided Flycatcher. — This 
bird I found rare at Boulder in May, but common on Pike’s Peak in June, 
in and about spruce timber, above 10,000 feet. I often heard their loud 
whistled wh’che-be'-u. Their ordinary chup-chup-chup-chup, or bil-bil , is 
Finch-like ; while, when they are excited, the rapid succession of their 
whistled notes might readily pass for a song. (Occasionally with a pecu- 
liar loud, harsh, almost abrupt pu-ee ?) 
39. Contopus virens richardsoni, Baird. Western Wood Pewee. 
— At Boulder, rather common after May 25. Song-notes, a harsh pe-ee 
or pee-wee , with nothing of the plaintive drawl of the Eastern bird (and 
perhaps , occasionally, a ch’pe’-bu or ch’pe'-phu) . These birds I often found 
with the following. 
40. Empidonax trailli pusillus, Coues. Western Traill’s Fly- 
catcher. — Common in shrubbery on or near the plains, and not at all 
shy. I found them already at Boulder, May 15. They habitually flirt 
the tail. Ordinary notes : whit and pu-ee' (and perhaps song-notes of 
ch’phe-bee). 
41. Empidonax hammondi, Baird. Hammond’s Flycatcher. — 
Similar to pusillus in habits and coloring, but with colors more contrasted. 
Ordinary note, an almost whistled pip or phip ; song-note, wh’che'-be'-u or 
whit-ch’bec' , not very abrupt, but with the head tossed. I nowhere found 
this species common. 
42. Empidonax flaviventris diflicilis, Allen. Western Yellow 
bellied Flycatcher. — A common summer resident up to 8,000 feet. 
Notes, a chip, a single clear whistle, pee , and then pee-wee , tolerably shrill, 
and in no way loud, plaintive, or drawling, but slender, clear, and rather 
decisive. Tail not flirted. This bird sometimes prefers a high, bare 
perch. Mr. Aiken speaks of its singing. I heard once a ch\ pee’ -wee-pee' - 
wee-pec' that I attributed to this species. May 21, 8,500 feet up, I observed 
a pair of Flycatchers that puzzled me : they were active, pertinacious, noisy 
little fellows, persistently remaining near the tops of spruces, especially 
dead ones, and taking their flights, often vigorously, at that elevation ; 
their notes were quick and generally shrill : ch’ putty -wa'ke, ch’pitty-wa'lce , 
ch’pe-wee’ , ch’ pu-ee , etc., besides shrill twitters, guttural sounds, and 
almost chattering. Could these have been the Yellow-bellied Flycatch- 
ers in the mating season ? I failed to identify. 
43. Panyptila saxatilis, Coues. White-throated Swift. — Rare 
about Boulder. About Manitou I found several communities and other 
pairs occupying canons and cliffs, but often visiting the village. Their 
sharp, vehement, rather coarse notes suggest at times a Woodpecker. 
Their nests, as well as I can make out, are of glued twigs, either resting in 
