Associated Species: Other species that may use habitat in a similar way and/or respond similarly to threats, management, and conservation activities include Sage Grouse, Sage Thrasher, Green-tailed Towhee, and Sage Sparrow.

Distribution: The distribution of Brewer's Sparrows generally coincides with the distribution of sagebrush in the West, from east-central British Columbia, southeast to southwestern Saskatchewan, then south to southern California and east to central New Mexico. A disjunct population in the Yukon Territory and northwestern British Columbia may be a separate species. In Colorado in Physiographic Area 87, this species is concentrated in the Northwest, with scattered breeders at other locations in suitable habitat.

Habitat Requirements: Brewer's Sparrows are tied closely to sagebrush, where they breed in tall, dense stands or in stands broken up by grassy openings. They also nest in other shrubs, such as willows, mountain mahogany, or rabbitbrush. These sparrows prefer an abundance of shrub cover: within a given habitat patch, their probability of occurrence increases with increases in total shrub cover.

Ecology: Brewer's Sparrows arrive in Colorado in mid to late April, and nesting begins by mid May. Most young fledge in June and July. Most birds have left the state by early October. They winter in the southwestern states and Mexico. Their diet consists of insects, spiders, and grass and forb seeds.

Management Issues and Conservation Recommendations: Brewer's Sparrows suffer habitat loss due to removal of sagebrush, usually for conversion to housing or to improve forage for livestock or wildlife. Treatment of large areas of sagebrush with herbicides causes individuals to abandon the treated area (Schroeder and Sturges 1975). Prescribed burns that remove no more than 50% of the sagebrush may result in a decline in local Brewer's Sparrow populations for 1-2 years, but populations should rebound after that (Petersen and Best 1987). These sparrows prefer large, contiguous sagebrush stands; the minimum acceptable stand size has not been determined but isolated stands of sagebrush smaller than 2 ha (5 ac) are not likely to be nesting habitat (Knick and Rotenberry 1995). Maintain contiguous sagebrush stands of at least 12 ha (30 ac).

Status and Reasons for Concern: This species is on the national Watch List, indicating a high conservation need throughout its range. Within Physiographic Area 87, BBS data show a statistically significant annual rate of increase between 1969 and 1996 (P = 0.03; n = 20 routes). However, BBS data for the period 1966-1996 reveal a significant, survey-wide annual rate of decline (P < 0.01; n = 397 routes). Brewer's Sparrows were present on an average of 57.68% (SE = 5.05) of the BBS routes run in Physiographic Area 87 in Colorado during 1988-1997, at an average abundance of 18.22 (SE = 2.40) individuals per route. The mean number of routes run each year was 11.4 (SE = 1.55). This species is monitored by MCB with point transects.

Biological Objective: Maintain or increase the species' distribution and abundance, with progress toward meeting this objective based upon results of BBS and MCB monitoring programs.

Selected References: Andrews and Righter 1992, Kingery 1998, Knick and Rotenberry 1995, Rotenberry et al. 1999, Short 1984.