Description
VOCALIZATIONS: Call notes include a sharp "peek" or "pip" given by both sexes, and a soft, descending "k-lear" or "k-lear whee-zee" most commonly given by males. Song is a burry "se-put tsurrt chu-lup," lower and huskier than dusky flycatcher (EMPIDONAX OBERHOLSERI), which is slightly more musical. The song sequence may consist of all three elements or the elements given singly or in couplets, such as "tseep tsurp." (Sedgwick 1994, NGS 1999). Males sing most frequently in morning and before dusk, but will sing throughout the day, and usually use perches in mid- to upper-canopy (Sedgwick 1994).
Habitat
BREEDING: Associated with cool forest and woodland, primarily in dense fir; found in western hemlock/western redcedar/grand fir forests (TSUGA HETEROPHYLLA/ THUJA PLICATA/ ABIES GRANDIS), red fir (ABIES MAGNIFICA), mixed conifer, Douglas-fir (PSEUDOTSUGA MENZIESII), ponderosa pine (PINUS PONDEROSA), lodgepole pine (PINUS CONTORTA), spruce-fir (PICEA ENGELMANNII/ ABIES LASIOCARPA) and aspen (POPULUS TREMULOIDES). Several studies across the species range show a strong association with old-growth or mature stands, and lower abundances in young, pole/sawtimber, or open-canopied stands (Sakai 1987 cited in Sedgwick 1994, Raphael et al 1988, Hejl and Woods 1991, Manual 1991, Sakai and Noon 1991, Hansen et al. 1995, Anthony et al. 1996, Hutto and Young 1999).
In Pacific Northwest Cascade forests, optimum habitat is dry or mesic old-growth or mature Douglas-fir (Manuwal 1991, Hansen et al. 1995); becomes rare where the density of trees with a greater than 10 centimeter dbh is either less than 60 trees per hectare or more than 600 trees per hectare (Hansen et al. 1995). Most abundant in mature (95-190 years) or mesic to dry old-growth (200-700 years; Manuwal 1991). In one study where the overstory decreased with stand age, however, the species was found to be more abundant in young stands than in mature or old-growth (Carey et al. 1991). In the Rocky Mountains, common in mesic hemlock/cedar/grand fir forests, mixed conifer, spruce-fir and aspen (Hejl et al. 1995). On Northern Rockies regional surveys, was most often observed in relatively uncut conifer forests and in riparian areas closely associated with conifer forests; showed a preference for western red cedar/Grand fir, Douglas-fir, ponderosa pine, and mixed conifer, and was detected more often in old-growth than mature stands (Hutto and Young 1999). Often in mixed broad-leaved and coniferous stands in western Montana (Davis 1954, Manuwal 1970); in Douglas-fir/ponderosa pine forests, the species is significantly more abundant in old growth (more than 200 years) than rotation-aged stands (80-120 years; Hejl and Woods 1991). In Oregon Douglas-fir forests, associated only on upslope sites compared to riparian sites in one study (McGarigal and McComb 1992), but on another study was found in sites along small streams within coniferous forest and was most abundant in old-growth or mature stands compared to young stands (Anthony et al. 1996). In California Sierra Nevada red-fir forests, abundance increased with increasing canopy closure; greatest abundances were detected in dense stands of more than 60 percent canopy closure (Hejl and Verner 1988). In northwestern California Douglas-fir, was twice as abundant in mature forest (trees greater than 60 centimeters dbh and greater than 40 meters tall; more than 100 years) than in pole/sawtimber stands (trees 6-40 meters tall with crowns less than or equal to 8 meters in diameter; Raphael et al. 1988).
Often nests in Douglas-fir or ponderosa pine (Bowles and Decker 1927, Sakai and Noon 1991), also western larch (LARIX OCCIDENTALIS), tanoak (LITHOCARPUS DENSIFLORUS), white fir (ABIES CONCOLOR), grand fir, aspen, birch (BETULA spp.), and maple (ACER spp.; Sedgwick 1994). Selects nest sites in forests with few, small understory trees, clumps of tall, dense conifers, and overstory trees with well-developed canopies (Manuwal 1970, Mannan 1984). Places nests in large (more than 27 centimeter dbh), tall live trees in Oregon mixed-conifer forests (Mannan 1984). In Douglas-fir/tanoak forest in northwestern California, nests in mature and old-growth forest, with nest concealed by foliage cover on a horizontal branch or fork of a live, tall, large-diameter tree (Sakai and Noon 1991). Nests from 2 to 20 meters up (see Bowles and Decker 1927, Davis 1954, Mannan 1984, Sakai and Noon 1991, Baicich and Harrison 1997).
NON-BREEDING: In migration and winter, passes through deserts and occurs in scrub, pine and pine-oak association (AOU 1983). In winter in Mexico and Central America, found in highland forests, humid to semi-arid pine, pine-oak, and evergreen forest and edge; mid- to upper canopy (Howell and Webb 1995). In western Mexico, apparently a pine-oak-fir forest specialist (Hutto 1992).
Ecology
Density estimates have been reported in a variety of habitats. In Northwestern California Douglas-fir (PSEUDOTSUGA MENZIESII) forest, 40 birds per 100 hectares in old-growth, 20 birds per 100 hectares in mature stands (Sakai 1987, cited in Sedgwick 1994); 14.1 birds per 100 hectares in mature forest, 6.9 birds per 100 hectares in sawtimber stands (Raphael et al. 1988). In Oregon coast range Douglas-fir forest, 69.9 birds per 100 hectares in young (40-72 years) stands, 50.6 birds per 100 hectares in mature (80-120 years), and 17.4 birds per 100 hectares in old-growth (200-525 years; Carey et al. 1991). In western Montana Douglas-fir/Ponderosa pine (PINUS PONDEROSA), 17.0-17.3 territorial males per 100 hectares (Manuwal 1970 cited in Sedgwick 1994). In a California mature mixed-coniferous forest and montane chaparral, 16.6-41.4 territories per 100 hectares recorded (North 1989, Purcell 1990, Nelson et al. 1991, Purcell et al. 1992a). In California old-growth mixed coniferous-red fir (ABIES MAGNIFICA) transition forest, 22.5-59 territories per 100 hectares recorded (Breese 1989, Kee 1990, Davis et al. 1991, Purcell et al. 1992b). In Colorado, 14-47 birds per 100 hectares in aspen, 14-28 birds per 100 hectares in aspen-conifer habitat (Beaver and Baldwin 1975).
Relative abundances range from an average 0.65 (Colorado) to 7.62 (Cascade Mountains) birds per 25-mile survey route (Sauer et al. 1997). Fall mortality of immatures apparently high (Johnson 1970). Shows low genetic variation as well as extreme morphological uniformity across a range spanning 30 degrees of latitude, possibly due to past population bottlenecks (Johnson 1966, Johnson and Marten 1991).