Habitat
BREEDING: Occupies, scrub, brushy, open areas and thickets with scattered trees, open coniferous forest, mountain chaparral, aspen groves, streamside willow thickets and brushy, open areas, often near water (AOU 1983, Sedgwick 1993b). In a limber pine-juniper woodland in Wyoming, breeding pairs occupied nest patches with greater foliage cover and greater density of trees than was generally available. Successful pairs had nests that were more completely concealed from below than unsuccessful pairs, and were in a patch with a greater density of small trees and a shorter distance from the nest tree to the next nearest tree (Kelly 1993). Requires low-growing trees and tall shrubs under scattered taller trees for cover. Canopy trees may be used for high singing posts and look-out perches.
In a three year study, Hutto and Young (1999) found Dusky Flycatchers in 317, 245 and 227 point-count sites in the Northern Rocky Mountains (western Montana and Northern Idaho). Individuals were detected most often in cottonwood/aspen, ponderosa pine, seed-tree cut, clearcut, old clear cut, riparian shrub and post-fire habitat. Most detections were in riparian areas and early-successional forest with a good shrub layer, conditions naturally provided in post-fire forests (Hutto and Young 1999). Sedgwick (1993a) reports finding Dusky Flycatchers most often in Ponderosa Pine (PINUS PONDEROSA) and Douglas-fir (PSEUDOTSUGA MENZIESII) forest, especially thinned coniferous forest or on logged-over slopes or shrubby openings. Rare or absent in areas with few or no shrubs (Andrews and Righter 1992).
In Colorado, breeds in fairly open or brushy habitats including ponderosa pine forest, lodgepole pine (PINUS CONTORTA), hillside shrublands including Gambel oak (QUERCUS GAMBELII), mountain mahogany (CERCOCARPUS MONTANUS) or serviceberry (AMALANCHIER ALNIFOLIA), riparian transition, spruce-fir, limber pine (PINUS FLEXILIS), Douglas-fir, montane and foothill riparian forests, small willow (SALIX sp.) thickets and aspen (POPULUS sp.) forests. Occupies, shrubby (RHUS sp., ARTEMISIA spp., PURSHIA sp.) slopes with scattered trees (PINUS spp, JUNIPERUS spp.), and in openings in pinyon-juniper (PINUS EDULIS-JUNIPERUS OSTEOSPERMA) woodland (Sedgwick 1987). From 2100-3000 meters (Sedgwick 1975, Sedgwick 1981, USFS 1982, Chase et al. 1983).
Habitat can overlap with both Gray and Hammond's Flycatchers but Hammond's prefers shadier, mature forests of spruce-fir, ponderosa pine, Douglas-fir, or mixed coniferous-aspen, particularly those with limited understory. Gray Flycatchers prefer drier habitats, including sagebrush and open pinyon-juniper woodlands, ponderosa pine, or oak-pine mixed with sagebrush or rabbitbrush (CHRYSOTHAMNUS sp., Sedgwick 1993b).
In New Mexico, breeds in riparian woodland and subalpine marsh at elevations where stream conditions provide sufficient permanent moisture for emergent plants, or for a narrow band of deciduous trees and shrubs. At low elevation, cottonwood and sycamore, at mid-elevation white alder (ALNUS RHOMBIFOLIA) and bigleaf maple (ACER MACROPHYLLUM), and at high elevation by willow. Also found in Great Basin shrub steppe in open to dense stands of shrubs and low trees, including big sagebrush (ARTEMISIA TRIDENTATA), saltbush (ATRIPLEX CONFERTIFOLIA), greasewood (SARCOBATUS VERMICULATUS), or creosote bush (LARREA DIVARICATA; USFS 1991).
In British Columbia, found in open ponderosa pine and mixed woodlands at low to moderate elevations (650-2,300m) and in Douglas-fir/aspen parklands up to 1200 meters (Campbell et al. 1997, Cannings et al. 1987). Found in relatively open, mixed or entirely forested landscapes, but most often in shrubby areas, occasionally in gardens, orchards and farmsteads. Prefer wild rose bushes and aspen for nesting but birch, willow, alder, Saskatoon, currants, chokecherry (PRUNUS VIRGINIANA), and red-osier dogwoods are also used (Cannings et al. 1987).
In California, found in pine forests with a relatively dense understory of coniferous seedlings and saplings (0.16 trees per sq m; 15 cm dbh; n = 7 plots; Johnson 1963). Breeds in mixed coniferous forest with a chaparral understory that is often composed of ARCTOSTAPHYLOS, CEANOTHUS, RIBES, PRUNUS, CERCOCARPUS, or ABIES (Johnson 1963). In southern Nevada, found in woodlands and montane forests (Alcorn 1988). In Baja California found in arid to semiarid scrub, semi-open areas and clearings with scattered trees and scrub, forest edge, nesting in aspen-conifer woodland (Howell and Webb 1995).
NON-BREEDING: Detailed information is lacking. Winters in interior Mexico in habitats similar to those on breeding grounds: scrub, pine-oak, semi-open country, forest edge, hedgerows (Sedgwick 1993b), and river-edge woodland (Edwards 1972) but also found in deserts (AOU 1983). Also occurs in semi-open country and in arid to semi-arid scrub and clearings with scattered trees and shrubs and forest edge (Howell and Webb 1995). Similar Pine Flycatcher (EMPIDONAX AFFINIS) usually in pine-oak forest and clearings. Gray Flycatcher prefers more open desert scrub (Sedgwick 1993b).
MIGRATORY: In migration occurs in all wooded or brushy habitats (Andrews and Righter 1992), including streamside habitats and woodlands. Prefers shady, broad-leaved cover during migration (Sedgwick 1993b). In Arizona, migrates more commonly in mountains than in valleys, at least in spring (Phillips et al. 1964), but also found in desert (AOU 1983). In New Mexico, inhabits shrublands and woodlands at lower (2800 - 5500 ft) and middle (5000 - 7500 ft) elevations in migration (Hubbard 1978).
Ecology
Males defend territories from other males, and at least where Gray Flycatcher also occurs in areas of local overlap, interspecificallly as well (Johnson 1963, 1966, Sedgwick 1993b). Where Dusky, Gray, and Hammond's flycatchers regularly come into contact, reproductive isolation among these three species is maintained by behavioral means (i.e., vocalizations and aggressive displays; Johnson 1963).
Verner and Boss (1980) estimate a territory size of 8.6-11.6 hectares in sparse conifer forest in California. The following are density estimates from a range of habitats and regions from breeding bird censuses compiled by Sedgwick (1993b): a) 237.5 territories per square kilometer in a montane mesic willow carr in Colorado (Hallock 1992); b) 20 territories per sq km in a limber pine-juniper woodland in California (Kelly and Kelly 1989); c) 30-45 territories per sq km in a mixed coniferous forest and montane chaparral in California (North 1989, Purcell 1990, Nelson et al. 1991, Purcell et al. 1992a) ; d) 30-54 territories per sq km in an old-growth mixed coniferous-red fir transition in California (Breese 1989, Kee 1990, Davis et al. 1991, Purcell et al. 1992b) ; e) 34 territories per sq km occurred in aspen-willow forest in Canada; and f) 31 territories per sq km in a black cottonwood floodplain forest in Canada (Erskine 1975a, 1975b).
Reproduction
Apparently monogamous. Pairs produce one brood per year and will renest after nest destruction (Sedgwick 1975). Nest building begins late May to early June. Entire reproductive cycle for first nest attempts, from arrival on breeding ground to fledging, is roughly 70 days. Nest initiation begins roughly 21 days after arrival on breeding grounds.
Female builds nest, generally in deciduous shrubs or trees, but occasionally in firs or ponderosa pines (Bent 1942), typically within a few meters of the ground (Sedgwick 1993b). When built in aspen, typically near the trunk in an upright crotch (Cannings et al. 1987). Willows, alders (ALNUS spp.), chokecherry, Rocky Mountain Maple (ACER GLABRUM), and mallow ninebark (PHYSOCARPUS MALVACEUS) among favored nest substrates. In California, nests are built in manzanita, Jeffery pine (P. JEFFREYI), and white fir (A. CONCOLOR, Sedgewick 1993b).
Eggs: 2-4, white, rarely with brownish flecks (Bent 1942, Bowles and Decker 1927). Eggs are laid 14 days later and incubated for 12-16 days (Sedgwick 1993, Johnson 1963, Pereyra 1990). Young are fledged an average of 15.6 days later (Sedgwick 1993b). Young are altricial. Female broods eggs and young. Both parents care for young (Sedgwick 1975). Fledglings are largely dependent until roughly 3 weeks after fledging and remain on parents' territory 3-4 wk following fledging (until early to mid-Aug in w. Montana (Sedgwick 1975).