Adult The upperparts (back, scapulars, rump) are olive to greenish-olive. The wings are blackish with olive-green fringes on the lesser coverts, two bold white (sometimes yellowish-white) wing bars, and narrow but sharply contrasting whitish to pale yellow edges on the tertials and inner secondaries (whitest on the tertials). The slender, shallowly notched tail is blackish-brown with narrow olive-green outer edges. The underparts are usually pale yellowish to brighter greenish-yellow, with an olive-green wash across the breast and sides, but some particularly dull individuals may virtually lack the yellowish tone to the underparts. The head is olive-green with slightly paler lores and a yellowish to olive-yellow throat. There is a complete, narrow, pale yellowish, almond-shaped eye-ring that is slightly pointed behind the eye. The iris is dark, the short bill is bicolored with a dark upper mandible and pinkish to orange lower mandible, and the legs and feet are blackish.
Juvenile This plumage is held until late summer of the first year, although immatures in fall migration and their first winter (not present in B.C) are similar. Juvenal birds are similar to adults, but are slightly duller and browner on the head and upperparts, have paler yellow on the throat and underparts, and have two buffy (rather than whitish) wing bars.
Measurements Total Length: 13-14 cm Mass: 10.5-12.5 g
The identification of the various Empidonax species in British Columbia ranges from difficult to extremely complex, and the Yellow-bellied Flycatcher is no exception to this. Correct identification will always be dependent on the assessment of multiple field marks rather than just a single feature. Although it is relatively distinct due to its (usually) extensive yellowish underparts, it does overlap in plumage characteristics with several other members of the genus and its identification, especially outside of the breeding season, is always going to be challenging. It is most similar in plumage to the much more common and widespread Pacific-slope Flycatcher, and fall vagrants anywhere in southern or central B.C. would most likely be confused with this species. Pacific-slope Flycatcher also has extensively yellowish underparts, but is a distinctly browner species (vs. greenish-olive in Yellow-bellied Flycatcher) and often shows a more prominent peak on the hindcrown (the head of Yellow-bellied is generally much more evenly rounded). The tertials and secondaries of Pacific-slope Flycatcher have less well-defined whitish to buffy feather edges, although Yellow-bellied Flycatchers in worn plumage can approach this characteristic. The wings also average overall browner and contrast less with the colour of the upperparts, but, again, Yellow-bellied Flycatchers in worn plumage can appear similar. During the breeding season, the distinctive song and call of Pacific-slope Flycatcher should serve to distinguish the species if it is heard, but this would not be possible with silent fall vagrants.
Immature and dull adult Yellow-bellied Flycatchers can show reduced or paler yellow on the underparts, with almost no yellow present in extreme cases, and can easily be confused with Least Flycatcher, which often occurs in the same areas as Yellow-bellied. These individuals are best identified by a combination of the overall more greenish-olive plumage (plumage more greyish-olive in Least), the less obvious contrast between the greenish-olive head and pale throat (contrast is better defined in Least), more almond-shaped eye-ring that forms a short point behind the eye (eye-ring usually rounded in Least, although some Yellow-bellied can show a similar eye-ring), entirely pinkish or orange lower mandible (lower mandible usually with a dusky tip in Least), and slightly longer primary projection. Some adult Least Flycatchers molt into fresh plumage on the breeding grounds, and thus can be washed with yellow on the underparts and may appear similar to Yellow-bellied Flycatcher, but these individuals can still be identified based on the above field marks.
The only other Empidonax species in B.C. that molts into fresh plumage prior to fall migration is Hammond’s Flycatcher, but this species should still be easily separated from Yellow-bellied Flycatcher despite the yellowish wash on the underparts at this time of year. Hammond’s Flycatcher is much greyer on the head and upperparts, although juveniles can be washed with olive on the back. It also has a distinctly large head, short bill, and long primary projection, giving it a distinctive structure. The lower mandible is primarily dark in Hammond’s Flycatcher, with some orange or pink at the base, and this feature alone should be sufficient to separate this species from Yellow-bellied Flycatcher with its entirely orange or pink lower mandible.
Source: Sibley (2000)
The male’s song is a low, hoarse, abrupt chebunk or killink, sometimes reduced to a single syllable psek or kik, and is repeated every 6-10 seconds for prolonged periods. The typical two-syllable song is very reminiscent of the song of the Least Flycatcher, but is lower-pitched, softer, and buzzier without the strong emphasis; the single-syllable song can also be confused with the pik call of the Downy Woodpecker. The commonly-heard call note is a short, clear, rising, whistled tuwee or chee-weep. During aggressive encounters, often gives a abrupt, buzzy brrrrt from flight. Other calls include a short, whistled pwee, a sharp, descending pyew (given by migrants), a long, plaintive peehk, and a sharp wsee.
Courtship Pair formation occurs immediately after arrival on the breeding grounds. The typical song, which functions both for territory establishment and mate attraction, is given from high, exposed perches within the territory (often from the tops of coniferous trees). The male’s ‘song flight’ is generally considered to be related to pair formation. During this flight display, which usually occurs in the predawn hours or at dusk, the male gives alternating chebenk and tu-wee calls. To initiate copulation, the female crouches on a branch and flutters her wings.
Nest Nest construction begins immediately after arrival on the breeding grounds, usually in late May or early June; the nest is built solely by the female. The nest is a cup of rootlets, plant stems, moss, and grasses that is usually situated on the ground (rarely as high as 2 m from the ground) within a depression in moss, soft wood, roots (including upturned tree roots), or mud; it is lined with dead grasses, rootlets, conifer needles, and moss rhizoids. The dimensions of the nest are ~8 cm wide and 9-10 cm deep, with an internal cup 2.5-5 cm deep. The nest is very well hidden and is generally completely concealed from above by overhanging roots or vegetation.
Eggs A single clutch of 3-4 (5) eggs is laid between mid-June and early July and is incubated by the female for 12-15 days before hatching. The smooth, slightly glossy eggs are whitish, often with fine brown or reddish-brown to pinkish or buffy speckling and spotting. Eggs are present in B.C. between mid-June and mid-July. This species is rarely a victim of Brown-headed Cowbird nest parasitism.
Young The young are fully altricial at hatching, with a sparse covering of brownish-olive down. The young are tended by both parents for 13 days before fledging, after which time they remain with the parents for up to 9 days before dispersing and becoming independent. Nestlings and dependent fledglings are found in B.C. between early July and late July.
Source: Baicich and Harrison (1997); Campbell et al. (1997); Gross and Lowther (2001)
This species primarily consumes flying insects throughout the year, with most prey captured in the air during short flights, or ‘sallies’ (behaviour known as ‘flycatching’ or ‘hawking’). Some prey is acquired through ‘sally-gleaning’ in which a flying bird picks the prey off of twigs or leaves; this foraging style is usually employed by birds that are foraging within a canopy of vegetation. This species also occasionally lands briefly on the ground to grab a prey insect, quickly returning to an elevated perch. Most foraging birds do not return to the same perch after sallies, except those that are returning from foraging on the ground. There are occasional reports of this species consuming berries on the breeding grounds (specifically, Poison-ivy berries in eastern North America), even when flying insects are present, but this appears to be infrequent.
Source: Gross and Lowther (2001)
This species breeds in a very particular, and often patchily-distributed, habitat in British Columbia which accounts for its very localized distribution in the province. Most birds breed in either second-growth stands of Lodgepole Pine or in and around Black Spruce/Tamarack bog-forests, although it also occurs in other mixed and coniferous forest types (including White Spruce, fir, birch, aspen), around beaver ponds, and around flooded alder-willow swamps. Most breeding sites are characterized by a relatively open understory with minimal shrub cover and a well-developed moss or lichen layer on the forest floor. Its preference for habitats that support a relatively low diversity of bird species, and thus attract minimal attention from observers, may be partially responsible for its poorly-known status in the province.
Source: Campbell et al. (1997); Greenfield (1998)
Breeds across the boreal forests of North America, from east-central Alaska, the Yukon, and northern B.C. east to Newfoundland and Labrador, and south to northern Minnesota, northern Wisconsin, and northern New York. It winters in southern Mexico and Central America and migrates east of the Rocky Mountains.
Breeding Uncommon and local in northeastern B.C. east of the Rocky Mountains, including the Peace River lowlands and the Fort Nelson area (with the largest numbers in the latter region). It is also widespread but uncommon and very local across central and northern B.C. west of the Rocky Mountains, south to the Bulkley Valley, Fraser Lake, the Prince George area, and the northern Cariboo Mountains and west to the Coast Mountains. Sporadic records farther south along the Rocky Mountain Trench (south to Kinbasket Lake) suggest that this species may breed in low densities farther south than current breeding records indicate. This species is generally highly localized and easily overlooked throughout its range in the province, especially in areas west of the Rocky Mountains.
Migration and Vagrancy This species is among the latest breeding birds to arrive in British Columbia in the spring, with the first individuals not appearing until early June; the appearance of spring migrants is rapid, however, and by mid-June the majority of birds are already on established territories. Fall migrants depart very early, primarily between late July and mid-August (with occasional individuals lingering in the central interior into late August).
This species is a casual fall vagrant to the south coast, with records for both western Vancouver Island and the Lower Mainland in late September and early October. It is accidental in fall (August) in the central interior south of the breeding range (Tatlayoko Lake). It is also casual during the breeding season (June-July) along the western slopes of the Coast Mountains along the northern coast of the province, south at least to Bella Coola. These coastal breeding-season records, as well as its tendency to go unreported even in areas where it occurs in moderate numbers, hint at the possibility of a breeding population along the northern and central mainland coast; much more coverage of this area would be necessary to thoroughly investigate this hypothesis.
Source: Campbell et al. (1997)
Population and Conservation Status
The Yellow-bellied Flycatcher has historically been considered a scarce species in British Columbia, occurring primarily in northeastern B.C. east of the Rocky Mountains. During the last several decades, however, it has appeared widely (although locally) across the northern half of B.C. west of the Rocky Mountains. In some areas, significant numbers have been found in suitable habitats in the central interior. This situation is correlated more with increased observer coverage of this area and increased awareness of the narrow habitat requirements and identification of this species than to any actual range expansion. A similar situation has occurred farther north in the Yukon Territory, where this species was historically (prior to 1993) considered casual but has now been found widely across the southern half of the territory. The Yellow-bellied Flycatcher is notorious for going undetected where it occurs, even when it is found in relatively large numbers. This appears to be due to a combination of several factors such as the tendency for its populations to be patchily distributed and to occur in remote areas of the province, its preference for very particular habitat types that support a relatively depauperate avifauna and are thus not typically sought out by birders, the similarity of its song to the much more common Least Flycatcher, its relatively quiet and unassuming disposition, and its extremely brief stay (<2 months) on the breeding grounds. As observers take these various factors into account, however, it is becoming apparent that the Yellow-bellied Flycatcher is not only much more widespread than was known but may be considerably more numerous.
As a result of the recent increase in reports of this species, it is apparent that populations are much more secure in the province than was previously suspected. As a result, it is not considered to be threatened or endangered in the province by the B.C. Conservation Data Centre (CDC), and is placed on their ‘yellow list’. Similarly, populations across Canada are large and secure and it is not recognized as a species of conservation concern by COSEWIC (Committee on the Status of Endangered Wildlife in Canada).
Source: Campbell et al. (1997); Sinclair et al. (2003)
This species is monotypic, with no recognized subspecies. Within the genus Empidinax, the closest relative of the Yellow-bellied Flycatcher is uncertain. Its affinities appear to lie more with western members of the genus than eastern members, however, and some genetic studies have suggested that the closest relative may be either Pacific-slope Flycatcher or Gray Flycatcher.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2023-10-02 2:00:03 PM]
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