To see this little Flycatcher at his best, one must seek the northern evergreen forest, where, far from human habitation, its mournful notes blend with the murmur of some icy brook tumbling over mossy stones or gushing beneath the still mossier decayed logs that threaten to bar its way. Where all is green and dark and cool, in some glen overarched by crowding spruces and firs, birches and maples, there it is we find him, and in the beds of damp moss he skillfully conceals his nest.
F. M. Chapman 1939
One of the characteristic breeding birds of the Canadian boreal forests and peatlands, the Yellow-bellied Flycatcher nests in cool, moist conifer or mixed forests, bogs, swamps, and muskegs, landscapes that are often flat or poorly drained. Nesting locations have often been romanticized by naturalists of the past and present day. Dickey (in Bent 1942) described its home in northern states and Canada as “the shadowy underwoods of evergreens, paper birches, and mountain ashes, where cranberries, trailing white snowberry, rare orchids, and an array of slightly emerald mosses carpet the forest floor and cover the crumbling logs.”
This is an elusive bird, but one of the most distinctive members of the genus Empidonax in appearance and habits. Its yellowish underparts and eye-ring make it the most easily identified eastern Empidonax, yet overall its plumage blends well with the mossy muskeg forests of its summer home or the Middle American rain forests of its winter home.
The Yellow-bellied Flycatcher is one of the continent's most overlooked birds and one of the last ones discovered here. Early ornithologists sometimes confused other species with this one, so historical accounts of the species are often misleading. Notoriously reclusive, this little flycatcher is more often heard than seen, although its soft voice is easily confused with that of other species. To make observation even more difficult, it does not linger long on its breeding grounds; its summer stay is one of the shortest of the Neotropical birds that visit the northern part of the continent for nesting, often less than 70 days. The nest of this species is well camouflaged and devilishly difficult to find; its reputation for concealment stretches from the historical age of oology to the present era of breeding bird atlases, where confirmation rates for this species are low.
As the genus name indicates, this Empidonax flycatcher is truly a “king of the gnats,” as well as of innumerable mosquitoes and other flying insects that inhabit its mossy summer home. Despite its small size and retiring reputation, the Yellow-bellied Flycatcher defends its nest pugnaciously from intruders. In close proximity, one grows to appreciate the tenacity and intensity that characterize the life of this small tyrant flycatcher. It indeed has “personality to burn” and gives any attentive observer a good show (Burt 2001). Since other flycatchers have yellow bellies, its name is not particularly diagnostic. Perhaps, “moss tyrant” would be a better fit.
Many aspects of the biology of this species are no doubt similar to those of other Empidonax flycatchers, but there are few studies to corroborate this. Studies of Yellow-bellied Flycatcher nesting biology are limited and refer to observations at just a few nests (Walkinshaw and Henry 1957, Walkinshaw 1967, Gross 1991, 2002; Martin et al. 2006). The species has received more attention on migration, however (e.g., Hussell Hussell 1982b, Hussell 1982c). Other aspects of its life history remain virtually uncovered.