Species: Empidonax oberholseri

Dusky Flycatcher

Species

Birds

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Terrestrial vertebrates: birds

Encyclopedia of Puget Sound

Classification

Kingdom

Animalia

Phylum

Craniata

Class

Aves

Order

Passeriformes

Family

Tyrannidae

Genus

Empidonax

NatureServe

Source:
ELEMENT_GLOBAL.2.100651

Classification

Other Global Common Names

Mosquero Oscuro - moucherolle sombre

Informal Taxonomy

Animals, Vertebrates - Birds - Perching Birds

Formal Taxonomy

Animalia - Craniata - Aves - Passeriformes - Tyrannidae - Empidonax - Formerly known as E. WRIGHTII [Wright's Flycatcher]; all records of E. WRIGHTII prior to 1939 and most prior to 1957 pertain to E. OBERHOLSERI (AOU 1983). See Whitney and Kaufmann (1985) for details on identification.

Ecology and Life History

Short General Description

A small bird (flycatcher).

Migration

false - false - true - 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).

Non-migrant

false

Locally Migrant

false

Food 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).

Reproduction Comments

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).

Ecology Comments

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).

Length

Weight

Conservation Status

NatureServe Global Status Rank

Global Status Last Reviewed

1996-12-02

Global Status Last Changed

1996-12-02

Other Status

LC - Least concern

Distribution

Conservation Status Map

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).

ELEMENT_GLOBAL.2.100651