Chestnut-sided Warbler    Dendroica pensylvanica

Migratory Status: Neotropical migrant

PIF Population Estimate: 9 400 000

Percent of western hemisphere population breeding in boreal forest: >25%

BAM Effective Detection Radius (m) : 61.95

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: -0.7 n.s. (-1.5 to 0.2)

Life History

The adult male Chestnut-sided Warbler is easily distinguished during the breeding season by its black eye and malar (i.e., sides of the chin) stripe, yellow crown and wing patches, and distinctive chestnut sides. Females are slightly duller in appearance, but retain most of the plumage characteristics of males.

The breeding range corresponds with the southern boreal forest, primarily restricted to the boreal plains and boreal transition avifaunal biomes (i.e., major regional bird communities). Within Canada, the breeding range extends from the Maritime Provinces to east-central Alberta. The breeding range also extends south into hardwood and mixed forests associated with the Great Lakes and the Appalachian Mountains. The winter range includes portions of southern Mexico, but it predominantly winters throughout Central America, as far south as eastern Panama.

The Chestnut-sided Warbler prefers shrubby and second-growth deciduous forests across most of its breeding range. Unlike many other North American wood warblers, it has benefited from the clearing of primeval forests and may continue to benefit from the expansion of forestry operations.

The slightly smaller size of the Chestnut-sided Warbler, relative to other North American wood warblers, may be an adaptive strategy to better facilitate its somewhat unique foraging strategy. This bird appears to forage heavily on the undersides of leaves and may be reliant on foliage insects as its main source of prey.

Reference(s)

Richardson, M., and D. W. Brauning. 1995. Chestnut-sided Warbler (Dendroica pensylvanica), The Birds of North America, No. 190. A. Poole and F. Gill, eds. The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists's Union, Washington, D.C.