Willow Flycatcher (Empidonax traillii) [XC301230]
by Dan Lane from El Cortijo del Lago, Santa Cruz de Yojoa, Cort\u00e9s, Honduras (call)
Willow Flycatcher (Empidonax traillii) [XC31223]
by Paul Driver from Michigan, Nyangquing Point Wildlife Area, United States (call)
Subspecies
Formerly considered conspecific with Alder Flycatcher (Empidonax alnorum). Geographical variation in plumage, wing morphology and vocalizations probably clinal, becoming browner overall in western and paler in more arid environments, and racial boundaries not well defined. Described subspecies campestris (from North Dakota, in northern USA) synonymized with nominate.
The following 4 subspecies are recognised:
adastus Oberholser, 1932 - Breeds south-western Canada (southern British Columbia) southern in USA to eastern California (east of Sierra Nevada) and in Great Basin and Rockies. Winters probably mainly western Mexico south to Panama.
traillii (Audubon, 1828) - Breeds southern parts of Canada (Alberta, Saskatchewan, Ontario, Quebec) and north-central and north-eastern USA. Winters south-western Mexico south to Panama and possibly extreme north-western Colombia, also rarely to north-eastern Ecuador.
brewsteri Oberholser, 1918 - Breeds extreme south-western Canada (south-western British Columbia) south, west of Cascades, to south-western California (west of Sierra Nevada). Winters probably mainly western Mexico south to Panama.
BirdLife International Species Factsheet