Habitat

Breeds most commonly in wet, deciduous thickets, especially those dominated by willows, and in disturbed and early successional habitats (Dunn and Garrett 1997). At northern limits of dis-tribution in n. Manitoba, in willow scrub near rivers, streams or lakes; dominant shrubs includes willows (Salix planifolia and S. pedicellaris) and tundra dwarf birch (Betula glandulosa) with canopy 1–2 m (Briskie 1995). In aspen parklands of central Alberta, uses willow patches (mainly Salix petiolaris) to feed and nest, quaking aspen patches (Populus tremuloides) to feed only; avoids grassland (CC). In Ontario, breeds in overgrown fields and pastures, along shore lines; mostly open deciduous or mixed habitats, both wet and dry; often near water but this relationship indicates presence of preferred nesting shrubs and trees, e.g., willow, alder (Alnus spp.), dogwood (Cornus spp.; Peck and James 1987). Michigan breeding habitats include shrub wetland, shrub uplands, old fields, blueberry (Vaccinium spp.) bogs, semiopen wet deciduous forest, and gardens (McPeek 1994). Also nests in thickets and hedgerows in human-influenced habitats in British Columbia such as power transmission lines, cultivated farmland, orchards, roadsides and suburban parks (Campbell et al. in press). Found from 100 m to 2,700 m in California (Small 1984) and Arizona (Phillips et al 1964); at higher elevations along watercourses with riparian growth.

On small islands off coast of Maine, in absence of other warbler species, may establish territories with extensive spruce (Picea spp.) or mature deciduous growth, a habitat seldom exploited on adjacent mainland (Hebard 1961, Morse 1973).

Resident forms in West Indies found in mangroves but may extend into dry scrub, freshwater swamps, riparian scrub and even humid forest on many islands (Raffaele et al. 1998). In Middle America, resident forms restricted to coastal mangroves, especially red mangrove (Rhizophora mangle); on Cocos I. and Galapagos Is. found more widely through scrub habitats (Dunn and Garrett 1997; see also Binford 1989).

On Dominica and Martinique, singing males of resident warblers seen in montane forests at elevations >300 m (NKK).

Mainly scrub/shrub and semiopen, second-growth forest, often associated with wetlands. Spring and fall migrants concentrated in same habitats most frequently used for breeding: e.g., forest edge and shrub habitats in Illinois (Graber et al. 1983), deciduous riparian woodlands in British Columbia (Campbell et al. in press). Spring migrants in se. Pennsylvania use a variety of habitats not used for breeding including wooded residential areas (deciduous trees along streets), and mature deciduous forests, but they almost always seek out edges within the forest (K. Russell pers. comm.). After trans-Gulf flight, during migratory stopover on Horn I., a barrier island along northern Gulf Coast, Yellow Warblers observed in shrub/scrub habitat (n = 16), pine forest (n = 3), and relic dune (n = 20; Moore et al. 1990).

Variety of wooded and scrubby habitats, including gardens, town plazas, second growth, brushy pastures and hedgerows, forest edge, streamside (riparian) woodlands, wooded marshes, agricultural lands, and other semiopen areas; Yellow Warbler commonly winters in mangrove associations and overlaps with resident Golden Warbler and Mangrove Warbler (Dunn and Garrett 1997).

In Oaxaca, Mexico, wintering Yellow Warbler (aestiva group) occurs from sea level to 1,600 ft [490 m] in mangrove swamp, Pacific swamp forest, deciduous forest and tropical evergreen forest (Binford 1989). In Colombia, as high as 2,600 m, but usually <500 m (Paynter 1995).