Pacific-slope Flycatcher

Empidonax difficilis

By Andrew McCormick

  • Length          5.5 in
  • Wingspan     8 in
  • Weight         0.39 oz
  • AOU Band code   PSFL

The Pacific-slope Flycatcher was formerly considered the same species as the Cordilleran Flycatcher Empidonax occidentalis and known as the Western Flycatcher. It is slightly smaller than the Cordilleran and is generally found west of the divide along the Cascade and Sierra Nevada mountain ranges. It is one of 11 North American flycatchers in the genus Empidonax, from the Greek for gnat master combining empid, a mosquito or gnat, and anax, lord or master, in reference to its feeding habit of hawking insects. The differences among the empids are slight and this bird is very difficult to identify by sight alone.  Hence the species name difficilis.   

Identification of male empids is accomplished primarily from their vocalizations and most reliably on the breeding grounds. Females do not sing. The Pacific-slope Flycatcher’s signature position note is an upward slurred tsweep.  This is very similar to the Cordilleran’s.  This note distinquishes both species from other empids. The location west of the Cascades will separate the Pacific-slope from the Cordilleran most of the time. Further study is needed in the area where both species are present to determine if this separation of species will remain permanent.

The Pacific-slope Flycatcher is a medium-size empid with a somewhat large head and a teardrop eye ring pointed behind the eye and broken at the top. Its wings are relatively shorter than other empids and the primary feathers have a short projection when folded giving the tail a longer look. Its upperparts are olive green but turn grayer as the feathers age in summer. Its legs are gray and its bill is bicolored with the lower mandible being yellow-orange to pinkish (Louther).  Although difficult to see in the moist woodlands the bird favors, the bill color can be a very good field mark.

The breeding range of the Pacific-slope Flycatcher is along the Pacific coast of California, the northwestern United States and British Columbia. The species is a medium-distance migrant which arrives on the breeding grounds in May and early June. Opportunistic in finding nesting sites these flycatchers will not only build in the fork of a tree, but also on a ledge in a stream bank, a stump, the upturned roots of a fallen tree, or shed rafters.  Generally all of these sites will be within 10 feet of the ground. Three to four whitish eggs with brown blotches will be deposited in the nest made of moss, grass, rootlets, strips of bark, lichens and leaves. Only the female incubates the eggs but both parents will bring food to the nestlings (Kaufman). Incubation lasts about two weeks and first flight occurs in another two weeks. There are many instances of a second brood in a season.

The population of Pacific-slope Flycatchers seems stable.  However, the species is at risk from human intervention. Care should be taken in “cleaning up” woodland areas.  Clearing downed trees and brush in Pt Lobos Reserve in Monterey Co., CA resulted in extirpation of the species as nesting sites were lost (Louther).

Photo by Mick Thompson

Photo by Mick Thompson

Hammond's Flycatcher

Empidonax hammondii

By Andy McCormick

  • Length          5.5 in
  • Wingspan      8.75 in 
  • Weight           0.35 oz
  • AOU Band code    HAFL

The Hermit Warbler is considered a specialist in living in the canopy of 200 foot tall conifers. In western Washington it populates Douglas firs, western hemlocks, and western red cedars. It winters in pine-oak forests in Mexico and in California it enjoys Jeffrey, pondersosa, and lodgepole pines. It forages so high that it is often heard long before it is seen. 
High Wire Specialist

The Hermit is not really solitary. It is just difficult to find high in the canopy. It begins foraging near the trunk and works its way toward the end of a branch, and then flies into a trunk to start on another branch, but not always in the same tree. It uses a variety of techniques employed by other canopy birds. It sometimes hover-gleans as Golden-crowned Kinglets do, as they pick insects from leaves and twigs while staying steady in flight. It will also hang onto branches as chickadees do. Using a third method similar to flycatchers, but less often than other means, it will sally out to hawk insects in the air. The Hermit Warbler’s diet consists almost entirely of insects. 

The Hermit Warbler migrates strictly along the Pacific Flyway. It is an early migrant arriving on the breeding grounds in early May. In the fall it leaves the breeding area earlier than other warblers, typically heading south in early August or even late July. It follows the forests until some birds settle in California and others winter in the forests of western Mexico.
Warbler Sisters

The Hermit Warbler is a sister species of Townsend’s Warbler (S. townsendi) and both are part of the virens superspecies which also includes the Black-throated Gray, Golden-cheeked, and Black-throated Green Warblers (Dunn and Garrett). The Hermit and Townsend’s Warblers enjoy similar habitat and hybridize regularly in areas where they overlap in Southwest Washington and on the east side of the Olympic Peninsula. Recent studies find that the range of the hybridization zone is moving south, which may indicate that Townsend’s Warbler is competitively superior to the Hermit Warbler (Pearson). Hybrids will generally keep the yellow face of the Hermit Warbler, and show yellow on the breast similar to Townsend’s Warbler. 

The Hermit is in the genus Setophaga, moth eater, from the Greek setos, moth, and phagein, eat, with the species name occidentalis, of the west, based on its habitat in western Washington, Oregon, and California. Difficulty in finding this bird led to the name Hermit. However, this species is not solitary in its habits (Holloway), and it will be found in mixed flocks in the early spring. 

Made in Washington
The Hermit Warbler breeds in Pacific Northwest coniferous forests. The female builds the nest on a horizontal branch out from the trunk. The nest is constructed as a deep cup built of weed stalks, pine needles, twigs, lichen, and moss and lined with softer materials such as soft bark and cobwebs. Usually four eggs are deposited. The timing of incubation and first flight are not well-documented. The young may leave the nest about 10 days after hatching (Kaufman). 

The Hermit Warbler is vulnerable to changes in forests in both its breeding and wintering areas. It is considered “a habitat specialist, has a narrow geographic distribution, and does not have a large population” (Reed in Pearson). Forest practices that include longer rotations between harvests on private land, reduced forest edge by keeping forest stands intact, and high canopy closure “…would likely benefit breeding, wintering, and migrating populations” (Pearson).

Photo by Julio Mulero

Photo by Julio Mulero

Olive-sided Flycatcher

Contopus cooperi

By Andy McCormick

  • Length          7.5 in
  • Wingspan      13 in 
  • Weight           1.1 oz
  • AOU Band code    OSFL

This bird of summer is often seems in need of refreshment and loudly calls out QUICK, THREE BEERS. Its indulgence makes it a favorite of birders and provides a readily identifiable bird song. The song is given from a prominent perch at the edge of, or in the middle of, a swampy area at the edge of a forest where flies and bees will be plentiful. The Olive-sided Flycatcher feeds by sallying out from its high perch to catch insects and returning to the same or close-by perch. 

The Olive-sided is similar in behavior to other pewees in the genus Contopus, short footed, from the Greek kontos, short and pous, foot. The reference is to the relatively short tarsi of this genus (Holloway). It shares the genus with the Western Wood Pewee C. sordidulus, a slightly smaller bird with similar flycatching behavior, but lacking the clear vest look. The Olive-sided species name is in honor of the zoologist William Cooper, 1798-1864, former director of the New York Lyceum of Natural History. 

The bird is olive-brown above with olive-gray sides and white throat, chest and belly giving the bird a distinctive appearance of wearing an unbuttoned vest (Altman & Sallabanks). It also has white tufts on the sides of the rump which are often hidden by the wings. It has a dark and blocky head with an equally heavy bill. From a distance the bird looks all gray. 

The Olive-sided breeds primarily in conifers. Both male and female live up to the family name Tyrannidae, Tyrant Flycatchers, by fiercely defending their nest, which is built on a horizontal branch well out from the trunk. Usually three pinkish-buff eggs with dark spots are deposited. Incubation is by the female only for a little over two weeks, and the young, fed by both parents, take flight in three weeks.

The conservation record of the Olive-sided Flycatcher is a difficult one. It has been extirpated (wiped out) in the early part of the 20th Century from southern New England, Maryland, Tennessee and the Carolinas and Sequoia National Park in California. Breeding Bird Survey analysis shows a decrease of nearly 74% throughout its historical range between 1966 and 2005 (Wells). Some suspect that changes to habitat on the wintering grounds may be causing declines. Others suggest that insecticide spraying has reduced the abundance of its primary prey. 

The Olive-sided does well in post-fire areas and forest fire suppression may have negatively affected this species. Ironically, tree harvesting, which leaves some snags and thus mimics burned areas, has attracted Olive-sided Flycatchers. But a theory has been offered that these areas can be an “ecological trap” which will attract birds to breed, but then expose them to more predators, such as squirrels and corvids, leading to increasing nest failures. 

The Olive-sided is a long-distance migrant that is more numerous in Western North America. It uses the Pacific Flyway to migrate to the Andes Mountains stretching from Venezuela to Columbia, where it is most common. Scientists need to “develop a baseline inventory of Olive-sided Flycatcher breeding and wintering populations, habitat needs…and factors responsible for continuing populations declines” (Wells).

Photo by Dan Streiffert

Photo by Dan Streiffert

Willow Flycatcher

Empidonax Traillii

By Hugh Jennings

  • Length          5-6 in
  • AOU Band code   WIFL

In North America, the Willow flycatcher inhabits more southern and western areas than its close relative, the Alder flycatcher.  It is common in our area in the spring and summer, found in a wide variety of habitats ranging from brushy fields to willows, thickets along streams, prairie woodlots, shrubby swales, and open woodland edges.

The range of the alder flycatcher overlaps with the willow’s range in the transition zone between prairie and boreal forest.

The willow flycatcher, 5-6” long, lacks an obvious, well-defined eye-ring, although the amount of color around the eye is variable.  In the West, birds tend to show no eye-ring, but eastern birds sometime have pale lores or a very thin eye-ring.  The bill is long and wide, with an orange lower mandible.  The bird’s back is brownish-green.  Song is a sneezy fitz-bew, both syllables equally accented.

In flight it catches insects, flying up to catch an insect and then returning to perch.  It feeds on a wide variety of insects, including at least 65 species of beetles.  About 41 percent of its food is wasps.  It builds a nest one to nine feet above ground, usually in an upright fork of a shrub, but occasionally on a horizontal limb.  Nests are usually built in an area of willows and plants of rose family.

Photo by Mick Thompson

Photo by Mick Thompson