Until recently placed in the genus Vermivora, the Nashville Warbler is now -- owing to growing molecular evidence -- grouped with a number of other warblers in the genus Oreothlypis. Its closest relative appears to be Virginia's Warbler (O. virginiae); some have considered it conspecific with this southwestern U.S. species.
Two disjunct populations of the Nashville Warbler breed in North America: one east of the Mississippi River (Oreothlypis ruficapilla ruficapilla) and a second in the northwestern United States and adjacent Canada (O. r. ridgwayi). Alexander Wilson first saw this species in 1811 near Nashville, Tennessee, and named it accordingly. The western Nashville Warbler, originally called the Calaveras Warbler, was first seen in Nevada by Robert Ridgway in 1868 and is named for him. Originally thought to be a southern species, the Nashville Warbler was considered rare by early ornithologists in the East. Its numbers increased in eastern coastal states in the latter half of the 1800s, reaching a peak around 1900 and then decreasing again in the early 1900s ( Bent 1953b ).
A ground nester, the Nashville Warbler inhabits varied terrain within its breeding range, including cut-over and second-growth areas; it winters primarily in central and southern Mexico. Males and females do not differ significantly in their plumage, and males do not go through a major color change in the nonbreeding season, which helps identify this species throughout the year.
Since Bent's ( Bent 1953b ) summary of the life history of the Nashville Warbler, this species has been included in several warbler studies within its eastern breeding range, particularly in Michigan, Ontario, and New Hampshire. It has not yet been the subject of a major study, however, and little is known about its behavior in western populations or on the wintering grounds.
Shifts in land use—clearing for farming in the early days of development in North America, regrowth of abandoned farm fields, and present-day clear-cut lumbering—probably account for the changes in density of this species. Its ability to breed in a variety of second-growth habitats makes it a fairly common warbler throughout North America, able to maintain, or even increase, in numbers in a time of extensive lumbering and clearing.