Least Flycatcher    Empidonax minimus

Migratory Status: Neotropical migrant

PIF Population Estimate: 14 000 000

Percent of western hemisphere population breeding in boreal forest: 65%

BAM Effective Detection Radius (m) : 56.25

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: -1.3 (-1.9 to -0.7)

Life History

The Least Flycatcher is a small, aggressive flycatcher that breeds in semi-open, deciduous and mixed woodlands throughout the boreal forest. This species exhibits an unusual social behaviour, whereby males often aggregate in groups or breeding clusters, leaving seemingly suitable breeding habitat available and unused in surrounding areas.

As with all Empidonax flycatchers, the Least Flycatcher can be a tricky species to identify in the field. Males and females look alike and have brownish-olive upperparts, whitish underparts, grayish breast and flanks with minimal yellow on the belly, two whitish wing bars, and a white eye-ring. This species is best identified by its primary song, which consists of two distinct notes, often described as “che-beck”.

The Least Flycatcher breeds mainly in open, deciduous woodlands, but also in orchards and shrubby fields from the Yukon Territory, eastward across the boreal forest to Newfoundland. Southward to the United States, this species breeds in the northern states and along the Appalachian Mountains in the east. It winters in young and maturing forests throughout Mexico and Central America.

Adult Least Flycatchers do not linger on the breeding grounds. By mid-July, or within 2 to 3 weeks after fledglings leave the nest, the adults will have started migrating back to their wintering grounds. In winter, both the male and female will defend a territory. Because of their quick departure from the breeding grounds, like many other species, adult Least Flycatchers do not molt until after the fall migration. In contrast, hatch-year birds remain on the breeding grounds for at least an additional month and begin to molt prior to and during migration.

The Least Flycatcher feeds mainly on flying insects and other invertebrates, occasionally supplementing its diet with fruits and seeds. This highly aggressive species often excludes competitors, such as American Redstarts (Setophaga ruticilla), from its territory and will chase other birds, such as the Blue Jay (Cyanocitta cristata) or Black-capped Chickadee (Poecile atricapillus), that come too close to its nest or young.

Reference(s)

Tarof, S., and J. V. Briskie. 2008. Least Flycatcher (Empidonax minimus), The Birds of North America Online, . A. Poole, Ed. Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database: http://bna.birds.cornell.edu/bna/species/099