Introduction

This small, gray warbler of the south-western Rocky Mountain states has been described in numerous accounts as shy, retiring, and not easy to observe. This combination of traits, in addition to slow progress in describing the natural history of its steep-sloped, xeric, piñon-juniper (Pinus edulis-Juniperus spp.) and oak (Quercus) woodland–dominated habitat, has no doubt helped make it one of the most overlooked warblers in North America. This bird, however, breeds over a broad portion of the western United States and occupies a landscape that is increasingly altered to accommodate cattle-grazing and human development. Even less is known about this warbler in its wintering habitat and potential breeding range in Mexico.

First described by Spencer F. Baird, Virginia’s Warbler was named for Mrs. Virginia Anderson, the wife of the discoverer and first collector, Dr. W. W. Anderson. The first collected specimen came from Fort Burgwyn, New Mexico, in 1858. Because this species is a relative latecomer to the study of North American ornithology, its description barely made it into Baird, Cassin, and Lawrence’s Birds of North America in 1860 as a footnote. It was originally placed in the now defunct genus Helminthophilia and has been placed in the genus Oreothlypis as well.

Current knowledge of this species comes from a scant number of studies—namely, T. Martin’s work on breeding biology and nest microsite selection in central Arizona (Martin 1988a, 1988b, 1988c, 1993, 1996, 1998, Martin and Ghalambor 1999, Martin and Li 1992). Earlier, N. Johnson clarified much of the known breeding range of this species and helped define its status as a separate species (Johnson 1976, Brush and Johnson 1976). Owing to a combination of factors—mainly rough, inaccessible breeding habitat, and difficulty in learning the behaviors of this timid bird—Virginia’s Warbler has not leapt out as a model study organism for many field biologists. Because of its association within a clade of extremely similar species that occupy a habitat gradient from desert to mixed coniferous forest, however, it could lend itself to comparative studies examining various topics, including habitat selection, plumage color, life history strategies, foraging strategies, and ecophysiology, to name a few. Still lacking, however, is very basic information on the distribution of this species, as well as on its habitat preferences, population density, and natural history. A large expanse of mountainous area in the Great Basin, for instance, has not been surveyed intensely for this species and there is also speculation that it may breed in southeastern Oregon.