A large warbler, averaging 14 cm long and 12 to 13 g. There are two well-marked subspecies groups - Myrtle Warbler (Dendroica coronata coronata
) and Audubon's Warbler (Dendroica coronata auduboni
). All plumages and subspecies possess the yellow rump that gives the species its name. Myrtle Warbler: adult male in breeding plumage is gray above, with black streaks on back; yellow crown-patch; black cheeks; white throat; and black breast, with yellow patches on sides. Distinct face pattern of black auriculars bordered by white supraloral spot, white postocular stripe, and white along lower rear portion of ear-coverts. Wings and tail black, with white wing-bars and white tail-spots. Adult female in Alternate plumage similar, but brown above and streaked below; auriculars brown or gray instead of black. In all Basic plumages, retains overall plumage pattern, including yellow areas and wing and tail marking, but body plumage is brown or brownish gray above and whitish below and black patches on ear-coverts and breast are lacking. Audubon's Warbler is similar but differs in having yellow throat, relatively plain face lacking postocular stripe, cheeks gray to blackish not contrasting with crown, more tail-feathers with white spots, white in wing usually more extensive. Head and back of adult Alternate-plumaged male varies from gray to completely black. Adults are easily distinguished from adults of other species that have yellow or yellowish rumps by having white and black versus yellow underparts (Hunt and Flaspohler 1998).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Western Hemisphere Range
Breeding range: predominantly mature coniferous and mixed coniferous-deciduous habitats. Migration: variety of habitats, although generally less common in forest interiors. In deserts of southwestern U.S., avoids arid lowland habitats and tends to occur at higher elevations in fall than in spring. Winter range: open areas, including second growth, edges, agricultural and residential areas, dunes, marshes, and shrublands; also a variety of relatively open forest types (Hunt and Flaspohler 1998).
During breeding season, mostly insects (adults and larvae) and other small invertebrates. On migration and in winter, insects and fruit, sometimes exclusively fruit, and some nectar (Hunt and Flaspohler 1998).
Nests typically on horizontal branch of hemlock, spruce, cedar, pine or tamarack. Female builds the cup shaped nest. Eggs are oval in shape. Egg color white to creamy white and marked. Clutch sized typically 4 to 5 eggs. Statewide, nesting is from late May to mid-July. Near Fortine, earliest date for flying young is July 2.