Introduction

Originally called the Mountain Mockingbird, the Sage Thrasher was first collected for science by John Kirk Townsend from the sagebrush plains along Sandy Creek near South Pass in southwestern Wyoming in 1834. In a coup exemplifying the competitive spirit of exploration and species discovery in the early 1800s, John J. Audubon managed to obtain the original specimen while Townsend was still afield and introduced the species to the scientific community (Mearns and Mearns 1992). In an effort to salvage credit for his friend, Thomas Nuttall wrote the original description of the species and published it under Townsend’s name (Townsend 1837, Mearns and Mearns 1992). Bent (1948) claimed the genus and the old common name (Mountain Mockingbird) were misnomers. His statement is true only if “mockingbird” describes a taxon rather than a behavior. The Sage Thrasher has a long, melodious song of great variety, reminiscent of a mockingbird’s song, and is found mostly in shrub-dominated valleys and plains of the western United States. It is considered a sagebrush (Artemisia spp.) obligate, generally dependent on large patches and expanses of sagebrush steppe for successful breeding.

The smallest of the thrashers, the Sage Thrasher is rather plain and seemingly unremarkable; it has a melodious, flutelike song, which can last several minutes without interruption, and an exaggerated, undulating courtship flight that often ends in a Bilateral Wing Display. Song and display are both welcome characteristics early in the morning on a spring day in the sagebrush deserts of the West. Typical of thrashers, this species is elusive when disturbed, frequently running on the ground rather than taking flight. It is known to reject cowbird eggs. Sage Thrashers feed mostly on insects on the ground, but they will take berries. The species tends to wander during migration, with individuals occasionally showing up as far east as the Atlantic seaboard.

This species’ populations are mostly stable where suitable shrub-steppe habitat remains. However, its numbers have been dramatically reduced, and in some cases, local populations have been eliminated, where there has been wholesale conversion of sagebrush rangeland.

The Sage Thrasher is poorly studied; much of the literature on this species is anecdotal, relating to its wandering habits during migration. Detailed information on its nesting ecology in Idaho and Oregon can be found in Reynolds and Rich 1978, Rich 1978b, 1980b, Reynolds 1981, and Rotenberry and Wiens 1989 . Foraging ecology has been addressed by Stephens (1985). This species and other sagebrush obligates were featured in recent landscape-level studies in southwestern Idaho on habitat relationships, fragmentation, and change (Knick and Rotenberry 1995a, 1995b, in press). The Colorado Bird Observatory recently completed a study, as yet unpublished, on nesting ecology of the Sage Thrasher in north-central Colorado (S. W. Hutchings in litt.). Two new studies through Boise State University on the impact of habitat fragmentation on this species are being conducted by S. T. Knick and B. C. Schoeberl in southwestern Idaho, and by J. R. Belthoff and C. W. Rideout in southeastern Idaho. Both projects are designed to provide land managers with much needed information for future conservation efforts.

In this account, observations and unpublished data from Rich and Stephens are indicated by TDR and DAS, respectively; Reynolds is designated REY.