Remsen, J.V. 1975 Chestnut-sided Warbler Dendroica pensylvanica May 10 Jumbo Res., Sedgwick Co., Colo.: 1♂ in row of willows along north edge of the lake; yellow crown, chestnut sides, white underparts, etc. May 13 Boulder area, Boulder Co., Colo.: 1♂ behind Ball Bros. at Arapahoe Rd.—yellow crown, chestnut sides, white underparts, etc.—watched for 5 minutes from extremely close range. May 14 Boulder area: 1♂ again behind Ball Bros.—song similar to Yellow Warbler but more irregular and “jumbled up”. Sep. 13 Horse Creek Res., Weld Co., Colo.: 1 imm.—bright green upperparts, forehead all yellow-green; white wingbars; white underparts. Oct. 12 Monterey area, Monterey Co., Calif.: 1 imm Carmel River—clean white underparts from chin to undertail—only black tip to corners of tail; White eye-rings on dusky grayish face; bright green upperparts, especially crown; two bright yellowish-white wingbars. Watched for over 10 minutes in cottonwoods, foraging in middle story, often darting out suddenly to foliage.