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Hammond's Flycatcher
Empidonax hammondii
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S3S4B
External links
General information
Hammond's flycatcher, Empidonax hammondii, breeds in the western United States, western Canada, and Alaska. It migrates to southern Arizona, Mexico, and Central America for winter. The species is fairly common in the high mountain forests of Utah during its breeding season (spring and summer).
Hammond's flycatcher prefers mature forest habitat when breeding, but deserts, scrublands, and woodlands are preferred during other times of year. The nest is high above the ground in a large tree. The female alone incubates the clutch of two to four eggs for about two weeks. Both parents attend to the young, which leave the nest at about 18 days of age.
This species is active during the day. Individuals forage by waiting on a perch for prey (flying insects) to come into range. The flycatcher then leaves the perch and captures the insect in flight.
Species range
BREEDING: east-central Alaska, southern Yukon, northeastern British Columbia, southwestern Alberta, western and south-central Montana, northwestern Wyoming, south through northwestern U.S. (Washington, Oregon, Idaho) to east-central California, Utah, northeastern Arizona, western Colorado, and north-central New Mexico (AOU 1998, Sedgwick 1994). Centers of breeding abundance, based on BBS data, are in the Pacific Northwest from northern California to British Columbia, and in the northern Rockies (Sauer et al. 1997). NON-BREEDING: southeastern Arizona, south through highlands of Mexico, Guatemala and El Salvador to Honduras and probably Nicaragua (AOU 1998).
Migration
Northbound migrants arrive in U.S. March-May (Terres 1980). Migrate earlier in spring and later in fall than dusky flycatcher (EMPIDONAX OBERHOLSERI; NGS 1999). In spring, migration lasts from mid-March to early June; males migrate ahead of females and first-year juveniles and pass chiefly through coastal states; second wave largely of females and fewer males passes through interior; timing and location of routes may be related to climatic conditions (Johnson 1965). Fall migrants pass through coastal states to Arizona from late August through late October; interior migration is shorter duration and peaks in mid-September; all then funnel through southeastern Arizona and southwestern Mexico (Johnson 1970).
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).
Food habits
Flies out from a perch, usually high in tree, to catch insects in the air. Will hover-glean in early stages of breeding season, later switching to flycatching and gleaning from woody substrates, probably related to prey availability (Sakai and Noon 1990). Eats caterpillars, butterflies, moths, beetles, flies, bees and wasps (Terres 1980, Sedgwick 1994). In a Colorado study, Coleoptera and Lepidoptera greatest proportion of diet by dry weight, followed by Diptera and Hymenoptera (Beaver and Baldwin 1975).
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).
Reproductive characteristics
Breeding season from early June to late July (Baicich and Harrison 1997). Clutch size is two to four. Incubation, by female, lasts 15 days. Young are tended by both adults, leave nest 17-18 days after hatching. Single-brooded; will replace lost clutches.
Threats or limiting factors
Threats to the species are largely unstudied. In the Great Basin, the species scored high for vulnerability to extirpation due to its rarity in the region, habitat specialization, potential vulnerability to cowbird brood parasitism, and its migratory status (Reed 1995). HABITAT LOSS: Occurs in commercially valuable coniferous forests, particularly mature and old-growth stands. Overstory removal eliminates habitat (Hagar 1960, Hansen et al. 1995) and the species would be likely to decline with continued widespread harvest by clearcutting or other overstory removal methods (Raphael et al. 1988, Saab and Rich 1997). Loss, reduction, or opening up of old-growth and mature forests will probably result in a decline in the breeding density (Sakai and Noon 1991, Hutto and Young 1999). May be sensitive to edge, forest fragmentation, and shrinking patch sizes (Aney 1984, Rosenberg and Raphael 1986, Hejl and Paige 1993). PARASITISM: Has been recorded as a brown-headed cowbird (MOLOTHRUS ATER) host, but no information on parasitism rates or behavioral response (Sedgwick 1994). PREDATION: Sixty percent of nests depredated by Steller's jay (CYANOCITTA STELLERI) in California study (Sakai 1988, cited in Sedgwick 1994). Also respond to chipmunks (EUTAMIAS spp.). Red squirrel (TAMIASCIURUS HUDSONICUS) and chickarees (T. DOUGLASI) are other potential nest predators. FIRE: Stand-replacing fires, crown fires and scorching destroy habitat, but persists in underburned sites (Johnson and Wauer 1994). PESTICIDES: No quantitative information available, but application of forest insecticides that eliminate aerial insects would destroy the food base.
References
- Biotics Database. 2005. Utah Division of Wildlife Resources, NatureServe, and the network of Natural Heritage Programs and Conservation Data Centers.
- Peterson, R. T., and V. M. Peterson. 1990. A field guide to western birds, 3rd ed. Houghton Mifflin, Boston. 432 pp.
