356 Birds of Colorado 
timber line; it is most common on migration in the plains, and nests 
most abundantly between about 7,000 to 9,000 feet. Gale took it at 
11,000 feet on Bald Mountain, September 15th, 1888. It reaches 
southern Colorado early in April and the mountain parks a little later. 
The following are dates: Pueblo, April 4th (Lowe), La Plata co., April 
3rd (Gilman), Mesa co., mid April till October (Rockwell), El Paso co., 
April 9th (Aiken), Sulphur Springs, April 26th (Warren, 08), Idaho 
Springs, early May (Trippe). It leaves in October—the latest I have is 
October 6th (Sapanero Creek, Gunnison co., Warren). 
Habits.—The Western Vesper-Sparrow frequents open 
country where there are few bushes, and is fond of 
cultivated fields, the valleys of the larger streams in the 
mountains and grassy hill-sides; it has a good variety 
of songs, some of them very sweet, and sings late in the 
evening, whence its name. The nest is placed on the 
ground, usually in an open field, clear of any shelter ; 
it is constructed of dried grass-stalks rather loosely 
put together, and lined with a little horsehair or other 
finer material. 
Freshly laid eggs are found as early as the beginning 
of May in the south, but not generally till the beginning 
of June in the north of the State, and perhaps later still 
in the mountains, but a second brood is sometimes 
raised. The eggs are greyish or greenish-white, blotched 
and spotted with reddish and purplish-brown. The 
brooding hen sits very close, and does not flush till 
nearly trodden on. 
Genus PASSERCULUS. 
Rather small terrestris], Sparrow-like Finches—wing under 3-0— 
with small, conical bills and exposed nostrils; wings short, but still 
exceeding the tail and tarsus combined ; less pointed than in Powcetes, 
the difference between the primaries and secondaries far less than the 
tarsus ; five outer primaries (ninth to fifth) more or less equal, the 
fourth distinctly shorter; tail nearly square about -65 length of wing, 
the feathers rather narrow but not attenuated or pointed at the tip. 
Plumage streaky, without white on the outer tail-feathers; a yellow 
superciliary stripe often present. 
