BIRDS OF COLORADO. 
II7 
the latter part of June. Leaves the mountains in August and 
the State in September. One of the most common Warblers of 
western Colorado. Comes east commonly to the edge of the 
plains and rarely to Fort Lyon, where it was seen occasionally 
and taken by Capt. P. M. Thorne. 
68ia. Geothlypis trichas occidentalis. Western Yellow- 
THROAT. 
Summer resident ; common. Almost confined to the 
plains, where it is common in migration and not uncommon as 
a breeder. Is found on both sides of the range, but only in the 
lowest portions scarcely coming up to 6,000 feet ; much less 
common in western Colorado than eastern. Arrives the first 
week in May, but sometimes reaches northern Colorado by the 
middle of April. 
683. Icteria virens. Yellow-breasted Chat. 
Summer visitant; accidental. The typical form from the 
east was found by Say in the Rocky Mountains at the head- 
waters of the Arkansas. (B. B. and R. Birds of N. Am.) 
683a. Icteria virens longicauda. Long-tailed Chat. 
Summer resident ; common. Scarcely found in the mount- 
ains, but common in the lower foothills and on the plains. 
Does not breed above 6,500 and is never seen above 8,000 feet. 
Found throughout the State, but most common at the western 
edge of the plains. Arrives the first week in May and laying 
begins the first week in June. 
685. Syivania pusilla. Wilson’s Warbler. 
Summer resident ; abundant. In migration is common or 
abundant throughout the State, in about equal numbers on the 
plains and in the mountains. Arrives on the plains about the 
middle of May and is common for ten days to two weeks. By 
June I has left the plains for the north or gone into the mount- 
ains. During the month of June, is moving up the mountains 
and by the end of June is at its summer home just above timber- 
line where during July it is the mo.st numerous insect-eating 
bird. Laying begins the last of June; young are able to fly by 
the latter part of July. The center of abundance during the 
breeding season is about 11,000 feet, but it has been known to 
breed from 6,000 to 12,000 feet. Is very common in the upper 
parks in August during its fall descent; reaches the lower parks 
in September; the plains in October and leaves the State late 
in this month. 
685a. Syivania pusilla pileolata. Pileolated Warbler. 
Migratory; rare. This is the western form, found regularly 
from the Great Basin to the Pacific. A specimen taken by 
