Empidonax oberholseri

Breeds w North America; winters to s Mexico.

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

Global Range: BREEDING: southwestern Yukon south through western Canada and western U.S. to southern Californa, southern Nevada, southwestern Utah, central Arizona, central and northeastern New Mexico; and east to southeastern Montana, western South Dakota, and central Colorado (AOU 1983, Sedgwick 1993). Known to nest in the Sierra San Pedro Martir, northern Baja California (Erickson and Wurster 1998). NON-BREEDING: southern California (casually), southern Arizona, and northern Mexico, south mostly in highlands to Guerrero and Oaxaca, casually south to northwestern Guatemala (AOU 1983, Sedgwick 1993).

Length: 15 cm

Weight: 10 grams

Systems

• Terrestrial

Comments: 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).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

A complete migrant, traveling regularly through the southwestern United States, casually through coastal Washington and Oregon, to Baja California, and east to central and south Texas (AOU 1983). Fall migration begins early to mid-August and most individuals are no longer on territory by late August (Sedgwick 1993b), but as early as 7 August (Sedgwick 1975). Fall migrants reported in Sonora as early as 6 August. In spring, males generally arrive more than one week before females, typically in the second week of May (Sierra Nevada, w. Montana; Johnson 1963, Sedgwick 1975).

Comments: Primarily an aerial sit-and-wait predator which sallies out to capture flying insects. Occasionally pounces on prey on the ground or gleans from tree bark (Bent 1942, Morton and Pereyra 1985, USFS 1982, Verner and Boss 1980). Thought to be entirely insectivorous during the breeding season. Consumes caterpillars, wasps, bees, grasshoppers, damselflies, moths and butterflies during the breeding season (Sedgwick 1975). No quantitative data on food choices or chronology and no information on food preferences during the non-breeding season (Sedgwick 1993b).

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).

Maximum longevity: 9 years (wild)

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).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There is 1 barcode sequence available from BOLD and GenBank.   Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen.  Other sequences that do not yet meet barcode criteria may also be available.

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Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 3
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

Canada

Rounded National Status Rank: N5B - Secure

United States

Rounded National Status Rank: N5B - Secure

Rounded Global Status Rank: G5 - Secure

Global Short Term Trend: Relatively stable (=10% change)

Comments: Populations appear to be steady over the short-term.

Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Populations appear to be steady over the long-term. The BBS indicates a non-significant survey-wide decline of -0.9 %/year for the period 1966-2000. More recent (1980-2000) declines of 1.0 %/ year are also not statistically significant (p = 0.12, Sauer et al. 2001). Many states and regions show population increases, none of which are significant. However, because of potential confusion with the similar Hammond's and Gray Flycatchers on BBS routes, especially during the early years of the program, trend analysis may not be entirely accurate. Analysis by Sharpe (1996) suggests Dusky Flycatcher may actually be more common now than in the past because of forest cutting practices that have benefited it.

Degree of Threat: Low

Comments: HABITAT DESTRUCTION/ALTERATION: Populations occurring in streamside habitats (e.g., willow thickets) are vulnerable to the array of human impacts to riparian habitat such as urbanization, channelization, water diversion, flood control projects, recreational development, grazing and agricultural conversion. These activities have destroyed or altered much riparian habitat in the western United States. In addition, the control of natural fires has created successional patterns that may be quite different from historical patterns and which may have effects upon habitat availability or quality for populations of this and other wildlife species. Wildfire suppression may also be detrimental by allowing succession to close forest gaps and encroach on shrubby open areas (Sedgwick 1993b).

COLLISIONS: Significant numbers of deaths of nocturnally migrating neotropical migratory birds have been attributed to collisions with human-made structures such as TV towers. The rapidly increasing numbers of tall communication towers being built throughout the range of this species along with the paucity of data on towerkills in the western United States suggest a current or potential threat to this species (Evans and Manville 1999). For more information visit Towerkill online: www.towerkill.org

SEVERE WEATHER: Late spring storms (rain and snow) have the potential to cause heavy mortality of adults (Eckhardt 1977) as well as egg and/or nestlings (Pereyra 1990).

PREDATION: Evidence for nest predation by red squirrels (TAMIASCIURUS HUDSONICUS) and chipmunks (Sedgwick 1975). In the Sierra Nevada, primary avian predator is ClarkNutcracker (NUCIFRAGA COLUMBIANA; M. Pereyra pers. comm. in Sedgwick 1993b).

BROOD PARASITES: Occasionally parasitized by the Brown-headed Cowbird (MOLOTHRUS ATER). One of nine nests in Montana (Sedgwick 1993b), < 3% of nests in Sierra Nevada (M. Pereyra pers. comm. in Sedgwick 1993b), and 16.2% of nests in British Columbia (Campbell et al. 1993) were parasitized.

Restoration Potential: Not currently in need of restoration.

Preserve Selection and Design Considerations: Management and restoration efforts will vary according to habitat type and region. Density generally 20-54 territories per square kilometer, occasionally over 230 territories per square kilometer (see Ecology Comments).

Management Requirements: Currently, relatively common and populations appear to be relatively stable with no special management efforts. Successful management will require protection of existing habitat and maintaining processes that create new habitat.

Sustaining viable populations will require a landscape and regional scale approach to habitat management. Maintaining a shifting mosaic of early successional habitat within the forest landscape can be accomplished through forest management practices and by reestablishing natural fire regimes. Natural or prescribed fire will have to be carefully implemented such that it will not establish large areas of the same age and structure but leave healthy mosaic patterns of various aged stands. Fires should not remove all shrubs but leave pockets of unburned shrubs.

The association of this species with shrubby habitats and logged over lands suggests that it benefits from forestry practices which thin dense coniferous stands or leave small openings in the forest. In some areas (e.g., Piceance Basin, Colorado) Dusky Flycatchers are found only in small, natural openings in pinyon-juniper forest, not in large clearings (Sedgwick 1981). That many individuals occupy clearcuts, partial- and seed-tree cut forests, at least in the northern Rockies, suggests that these treatments may not be detrimental (Hutto and Young 1999). Forest management should focus on maintaining a designated minimum acreage of suitable habitat, especially where logging and fires affect forest size, shape and plant species composition. Using chaining to fell vegetation may create adequate early successional stages as well.

Protection and restoration of riparian zones are a high priority throughout the western United States where development, water management activities, grazing, and agricultural practices have had significant impact on these communities and have caused regional endangerments of a number of bird species. Maintaining the integrity of riparian areas, especially at higher altitudes will benefit Dusky Flycatcher populations.

Grazing by both domestic livestock and native ungulates, particularly elk, can have significant impacts on aspen regeneration and shrub-forb structure of aspen-dominated woodlands (Shepperd and Fairweather 1994), which are a major source of habitat for Dusky Flycatchers in the northern Rockies. Better control of domestic livestock use (e.g. on Federal lands in the U.S.) could make a substantial difference in the health of the riparian communities and benefit populations of this species. In many cases, total removal of domestic livestock is not needed to make a substantial improvement in riparian vegetation condition; simply a change in the season of use and or change in the length of use of the riparian pastures (Myers 1991).

Management Programs: There are no management programs specifically targeting Dusky Flycatcher.

Monitoring Programs: Detected on the BBS in adequate numbers for trend analysis at survey-wide, state, and physiographic region scales. The BBS is the only systematic survey that gathers data throughout the breeding range of most neotropical migrants (Sauer et al. 2001). Dusky Flycatcher is monitored by this survey, but is not a special target species. Also detected on the U.S. Forest Service's Landbird Monitoring Program and the Canadian Migration Monitoring Network of Bird Studies Canada and the Canadian Wildlife Service. Specialized monitoring, however, is needed to provide information on trends and habitat relationships at smaller scales.

Management Research Needs: Research to improve management for this species should compare demographic parameters (e.g., reproductive success, site fidelity, survivorship) in managed forest types with post-burn forest and other habitat types. The possibility that humans are creating "ecological traps" by attracting this species to artificially created situations (cut forests) where they could have poor survival or reproductive success remains a possibility and merits study (Hutto and Young 1999). Landscape relationships, including area sensitivity, juxtaposition of habitats, and use of corridors are virtually unknown. Quantitative data on habitat associations and ecology of this species during the non-breeding season are lacking and investigations that yield such information should be of high priority.

Biological Research Needs: Like the similar Gray and Hammond's Flycatchers, this species has a broad distribution and is relatively common on the breeding grounds, but is still poorly known. More information is need on basic natural history. Further study is needed on breeding cycle, growth and development of young, parental care, and demographic variables (productivity and survival).

Stewardship Overview: A fairly common breeder throughout mountainous western North America, occupying scrub, brushy, open areas and thickets with scattered trees, and open forests, often near riparian areas. Populations appear to be stable to increasing. The principal known threat is destruction or alteration of riparian and shrubland communities by grazing, agriculture, and other development. Fire suppression that allows forest succession to encroach on forest gaps and other shrubby habitat may also reduce available habitat. Little is known about the ecology of or threats to this species on its non-breeding grounds.