Breeding Ranges of Willow Flycatcher Subspecies
There are four generally recognized subspecies of the Willow Flycatcher (Empidonax
traillii), each of which has a distinct breeding range (see range map below):
- E.t. extimus (Southwestern Willow Flycatcher): breeding range includes southern California (from the Santa Ynez River south), Arizona, New Mexico, extreme southern portions of Nevada and Utah, extreme southwest Colorado, and western Texas. Records of probable breeding Southwestern Willow Flycatchers in Mexico are rare, and restricted to extreme northern Baja California del Norte and Sonora.
- E.t. adastus: breeds from Colorado west of the plains, to the west through the intermountain/Great Basin states, and into the eastern portions of California, Washington, and Oregon.
- E.t. brewsteri: is found breeding from central/coastal California north, through western Oregon and Washington to Vancouver Island.
- E.t. traillii: breeds across the middle and northern United States and southern Canada, from New England and Nova Scotia west, through northern Wyoming and Montana, and into British Columbia.
Some recent research suggests there may be a fifth subspecies (E.t. campestris)
distinct from E.t. traillii and occupying breeding areas in the northern and
western portions of E.t. traillii range.
The breeding range distribution of the races of the Willow Flycatcher. Modified from Unitt
(1987) and Browning (1993).
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