Warbling Vireo (Vireo gilvus) [XC575834]
by Eric DeFonso from Provo River Valley, Wasatch County, Utah, United States (song)
Warbling Vireo (Vireo gilvus) [XC401111]
by Jeff Dyck from Las Cabras, \u00c1lamos, Sonora, Mexico (call, interaction calls)
Subspecies
Eastern Warbling-Vireo (Vireo gilvus) and Western Warbling-Vireo (Vireo swainsonii) (Sibley and Monroe 1990, 1993) have been lumped into Vireo gilvus following AOU (1998).
Sometimes placed in a separate genus, Melodivireo. May form a superspecies with Brown-capped Vireo (Vireo leucophrys), and often considered conspecific, but the two differ in plumage and some vocalizations. Nominate subspecies has been treated as representing a single monotypic species, the other four subspecies together forming a separate species, on basis of an alleged degree of reproductive isolation of the two taxa in overlap zone in southern Canada (Alberta). Further study is required.
Proposed subspecies leucopolius, described from western USA (Warner Mts, in south-eastern Oregon), considered synonymous with swainsoni; petrorus (from Wyoming, in USA) and connectens (from Chilpancingo, in Guerrero, in south-western Mexico) both subsumed in brewsteri.
The following 5 subspecies are recognised:
swainsoni Baird, SF, 1858 - Breeds from south-eastern Alaska and western Canada (southern from southern Yukon, south-western Mackenzie region and western Alberta) southern in western USA (east to northern Montana) to south-western California. Migrates to western and southern Mexico, Guatemala, Honduras and western Nicaragua. Considered by some authors to be a distinct species, Western Warbling-Vireo (Vireo swainsonii).
brewsteri (Ridgway, 1903) - Breeds Rocky Mts from south-western Montana and southern Idaho south through south-western Texas to western Mexico (south to south-central Oaxaca). Winters in Mexico. Considered by some authors to be a distinct species, Western Warbling-Vireo (Vireo swainsonii).
victoriae Sibley, 1940 - Breeds Cape region of Baja California (western Mexico). Wintering area unknown. Considered by some authors to be a distinct species, Western Warbling-Vireo (Vireo swainsonii).
sympatricus (Phillips, AR, 1991) - Central Mexico (northern and east-central Puebla). Considered by some authors to be a distinct species, Western Warbling-Vireo (Vireo swainsonii).
gilvus Vieillot, 1808) - Breeds southern Canada (central Alberta east to extreme south-western Ontario and New Brunswick) and USA (eastern from northern Montana, south to southern Oklahoma, Louisiana and Virginia). Migrates to Central America.
BirdLife International Species Factsheet