Say’s Phoebe (Sayornis saya) nests in western North American from subarctic Alaska south to central Mexico. Four subspecies of it have been named. From north to south these are S. s. yukonensis Bishop (type locality Glacier, White Pass, Alaska), S. s. saya (Bonaparte) (type locality near Pueblo, Colorado), S. s. quiescens (type locality San José about 45 miles east of San Quintín, Baja California), and S. s. pallida (Swainson) (type locality southern central plateau of Mexico). Browning (1976) reviewed the literature on Say’s Phoebe and in a detailed study of a large collection of adults reached the conclusion that yukonensis is not valid on either the basis of color or by measurements. He reiterated the problems in assessing geographic variation in this species: fading of the plumage because of exposure to the sun (considerable in this species of open habitats that molts only once per year) and foxing of the plumage (shifting of grays to browns with a specimen’s age in the museum). Rea (1983) enlarged on the problems, pointing out that the birds may leave nesting areas prior to molting and that wintering populations may be mixed, consisting of two or more subspecies. He suggested that birds in fresh juvenile plumage may be the best basis for working out geographic variation in the species, and he noted that 9 of the 11 specimens in the type series of yukonensis are juveniles (Bishop 1900). Browning did not mention the juvenile plumage. Rea (1983:185, map) extended the nesting range of quiescens from Baja California to central Arizona (Pima and Pinal counties).