The Dusky Flycatcher (Empidonax oberholseri) is a small passerine bird belonging to the tyrant flycatcher family. It breeds in western North America from southeastern Alaska across western Canada to the western Great Lakes region, and migrates to winter in western Mexico and Central America as far south as Panama. In this article, we will take an in-depth look at the range and habitat of the Dusky Flycatcher throughout its annual cycle.
Breeding Range
The Dusky Flycatcher breeds in forests across much of western North America. Its breeding range extends from:
- Southeastern Alaska west through the Aleutian Islands
- Southwestern Canada through British Columbia, Alberta, Saskatchewan, and Manitoba
- The western United States including Washington, Oregon, California, Idaho, western Montana, Wyoming, Colorado, and the western Dakotas
- As far east as northwestern Minnesota
Within this broad region, the Dusky Flycatcher nests in a variety of forest habitats including:
- Coniferous forests dominated by spruce, fir, pine, juniper, redwood, and cypress
- Aspen groves
- Mixed deciduous-coniferous forests
- Open woodlands
- Forest edges and clearings
They are generally found at elevations up to 10,000 feet in mountainous areas. Their breeding habitat preferences tend to include forests with an open understory and areas with standing dead trees (snags).
Some key areas where Dusky Flycatchers are abundant during the breeding season include:
- The Cascade Mountains and Sierra Nevada in Washington, Oregon, and California
- The Rocky Mountains in Colorado, Wyoming, Idaho, and Montana
- The Appalachian Mountains in Alberta and British Columbia
- Coastal forest ranges in southeast Alaska
Density and Population
Research estimates there are approximately 15 million Dusky Flycatchers across their breeding range. Their population trend has been stable to slightly declining in recent decades according to monitoring programs such as the North American Breeding Bird Survey.
They can be locally common within suitable habitat across the western interior of North America during summer, with breeding densities ranging from just a few pairs per 100 acres in marginal habitat up to 50-100 pairs per 100 acres in prime habitat. Their populations are scattered and localized east of the Rocky Mountains.
Migration and Winter Range
The Dusky Flycatcher is one of the latest spring migrants of all the passerines that breed in North America, not arriving on breeding grounds until May or even early June. They begin departing on fall migration in late August and September.
Their winter range extends from southern California and Arizona south through western Mexico to the highlands of Guatemala and El Salvador. Some vagrants may reach as far south as Costa Rica and Panama.
Key wintering areas include:
- Southwestern California from Santa Barbara south to Baja
- Southern Arizona south through the Sierra Madre Occidental and Sierra Madre del Sur mountain ranges in Mexico
- The Central Mexican Plateau
- The Pacific slope of Chiapas and Guatemala
- The interior highlands of Honduras, El Salvador, and Nicaragua
During winter they inhabit tropical deciduous forests, pine-oak woodlands, cloud forests, and second growth. They tend to occupy middle and lower strata of the forest.
Stopover Habitats
On migration between their breeding and wintering grounds, Dusky Flycatchers utilize a variety of forest and woodland habitats across the western United States, Mexico, and Central America.
Some important stopover sites include:
- Riparian woodlands in desert canyons of the southwest U.S.
- Oak-juniper woodlands on the Edwards Plateau of Texas
- Tropical deciduous forests along Mexico’s Pacific coast
- Pine-oak forests of the Sierra Madre Occidental
These areas provide important resting and refueling sites where the flycatchers can replenish energy reserves and safely shelter during the long migrations between their breeding and wintering grounds.
Habitat Characteristics
Throughout its range across western North America and Central America, the Dusky Flycatcher shows a preference for certain habitat characteristics and ecological niches:
Canopy Gaps
Duskies are often associated with small forest openings, edges, gaps in the canopy, and areas with a broken or open understory. They perch on the top of tall snags or dead branches to flycatch for insects.
Elevation
They breed at elevations up to 10,000 feet in mountain ranges, and migrate through passes as high as 12,000 feet. They winter down to sea level.
Forest Type
Coniferous and mixed forests are used during breeding. On migration and wintering grounds they utilize a broader range of deciduous and coniferous forests.
Forest Succession
They prefer mid-successional forest and tend to avoid dense, mature forests as well as very recent burns or clearings.
Edges
Forest edges, openings, and clearings are frequently used for foraging on breeding and wintering grounds.
Water
Access to water is important on breeding grounds and migration stopover sites. They are often found near streams, lakes, ponds, and wet meadows.
Territory Size
Breeding territories range from 1-6 acres in size, increasing in area with latitude and elevation. At higher elevations, territories may encompass 10 or more acres.
Threats and Conservation
The Dusky Flycatcher remains a widespread and common species, but does face some conservation threats and population declines:
- Habitat loss on wintering grounds in Mexico and Central America
- Climate change disrupting migration timing and breeding habitats
- Increasing severity of forest fires in the western U.S.
- Brood parasitism by Brown-headed Cowbirds
Conservation priorities include protecting key wintering habitats in Mexico and farther south, managing fire regimes and climate risks across breeding lands, and maintaining large tracts of mid-successional forest across their range.
Ongoing monitoring through programs like the North American Breeding Bird Survey will also be important to track populations over time. As a habitat specialist, the Dusky Flycatcher makes an excellent indicator species for the health of western montane forests.
Conclusion
In summary, the Dusky Flycatcher breeds in coniferous and mixed forests across much of western North America as far east as Minnesota. It migrates long distances to overwinter in pine-oak forests, tropical deciduous forests, and cloud forests from Mexico to Panama. Canopy gaps, forest edges, snags, and access to water provide ideal habitat. Conservation of breeding and wintering grounds will be key to ensuring the long-term viability of Dusky Flycatcher populations.