BIRDS OF COLORADO. II7 



tlie 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 

 commorf*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. Sylvanta 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. Sylvania pusilla pileolata. Pileolated Warbler. 



Migratory ; rare. This is the western form, found regularly 



from the Great Basin to the Pacific. A specimen taken by 



