Foraging and habitat relationships of the sibling species Willow Flycatcher (Empidonax traillii) and Alder Flycatcher (E. alnorum) in southern Ontario

Abstract

A northward expansion of the range of Willow Flycatchers has resulted in regions of secondary contact with Alder Flycatchers. The foraging ecology of both species overlaps extensively for both mutually allopatric and sympatric populations. Willow Flycatchers choose a more xeric upland habitat in southwestern Ontario than they do farther north at a site of secondary contact near Stouffville, Ontario. Alder Flycatchers at both Stouffville and Ottawa show similar habitat preferences. Habitat types chosen by both species at Stouffville overlapped considerably. Despite the extensive niche overlap at Stouffville, no evidence of competition between the species was observed.