Introduction

One of the characteristic breeding birds of the Canadian boreal conifer 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. It 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 Meso-American rain forests of its winter home. On breeding grounds, this flycatcher reigns over an elfin world of sphagnum mosses, bunchberry, twinflower, and goldthread under the shady boughs of conifers.

The Yellow-bellied Flycatcher is one of the continent’s most overlooked birds and one of the last ones discovered here. Early ornithologists often 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 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. This flycatcher’s reputation for concealment stretches from the age of oology to the era of breeding birds 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 characterizes the life of this small tyrant flycatcher. 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 corrobor-ate this. The only studies of Yellow-bellied Flycatcher nesting biology refer to observations at just a few nests (Walkinshaw and Henry 1957, Walkinshaw 1967, Gross 1991). The species has received more attention on migration, however (e.g., Hussell 1982a, 1982b). Other topics are virtually uncovered.