The Willow Flycatcher was listed as "Status Undetermined" in the 1985, 1991, and 1996 Status of Alberta Wildlife reviews based on the lack of information on the distribution and abundance of this bird (Alberta Fish and Wildlife 1985, Alberta Fish and Wildlife 1991, Alberta Wildlife Management Division 1996).
The Alberta Natural Heritage Information Center (ANHIC 1999) ranked the Willow Flycatcher as S2 which means it is rare throughout its range or in the province (6 to 20 occurrences) and may be vulnerable to extirpation.
British Columbia does not list the Willow Flycatcher as a species that is rare, endangered or vulnerable (British Columbia Conservation Data Centre 1999). Saskatchewan ranks the Willow Flycatcher as S4 (abundant, apparently stable, Saskatchewan Conservation Data Centre 1998). The Willow Flycatcher is ranked as S3 (uncommon) in Manitoba (Manitoba Conservation Data Centre 1998) while Ontario ranks it as S5 (widespread and stable, Ontario Natural Information Centre 1999).
Washington and Montana list the Willow Flycatcher as S5 (Washington Natural Heritage Program 1997, Montana Natural Heritage Program 2000). Oregon lists the status of the Willow Flycatcher subspecies E. traillii brewsterii as "vulnerable" and E. traillii adastus as "undetermined" (Oregon Natural Heritage Program 1998). In the southwestern United States, the Willow subspecies E. traillii extimus is considered "endangered" due to a population crash from loss of riparian habitat, cattle grazing and Brown-headed Cowbird parasitism (USFWS 1995). Arizona, New Mexico, Nevada, California and Utah all list the southwestern Willow Flycatcher subspecies as "endangered", or a species of concern.
Empidonax traillii is listed under the Natural Heritage Global Rank G5 (widespread and stable).