Brown Thrasher (Toxostoma rufum)

Photo by Jack BartholmaiBrown Thrasher by Jack BartholmaiBrown Thrasher distribution map

Status/Protection

Population Information

The Federal BBS information can be obtained at http://www.mbr-pwrc.usgs.gov/bbs/bbs.html by clicking on Trend Estimates and selecting the species in question. All estimates are for time period (1966-2005).

Life History

Habitat Selection

The Brown Thrasher occurs in a wide variety of habitats, including large clearcut areas with oak or other deciduous tree regeneration. It reaches its highest densities on the edge of shrub habitat or mid-successional forests (Cavitt and Haas 2000). Although an edge species, Brown Thrashers are more likely to occur along fields >6 hectares (Knutson et al. 2001). The Brown Thrasher nests in hedgerows and along the edges of fields, farmsteads, and deciduous forests (Robbins 1991, Knutson et al 2001). Isolated shelterbelts and shrub patches may afford greater nesting success than those close to other wooded habitats (Haas 1997). Isolated patches may be less accessible to mammalian and other types of predators.

Habitat Availability

Brown Thrashers remain widespread in the state and reach some of their highest densities in the large managed barren systems of northwest and northeast Wisconsin (Mossman et al. 1991). However, changing agricultural practices are a conservation concern for this species. Many landowners fail to recognize shrubs as a valuable habitat component (Knutson et al 2001). Consequently, hedgerows have largely been replaced or have grown into mature windbreaks in many agricultural areas. The conversion of barrens habitat due to woody encroachment and fire suppression also reduces suitable habitat for this species (WDNR 2005).

Population Concerns

Brown Thrasher population declines were detected as early as 1903 in Wisconsin (Robbins 1991). Current Breeding Bird Survey data indicate persistent declines statewide (Sauer et al. 2005). However, it remains a common nester across the southwestern two-thirds of the state and a fairly common breeder in the northeastern one-third. During the six-year period of the Wisconsin Breeding Bird Atlas (1995-2000), observers reported Brown Thrashers in 73% of the quads (Harriman 2006).

The loss of barrens and early-seral shrublands are concerns in Wisconsin (WDNR 2005). Brown-headed Cowbird parasitsm does not appear to be a major threat. Brown Thrashers are known to remove cowbird eggs from their nests (Cavitt and Haas 2000). 

Recommended Management

Management prescriptions rarely include enhancement of shrub habitats. However, without proper management, shrub habitats lack long-term stability. Efforts are needed to preserve and/or enhance shrubland habitats and mid-successional stages of forest in Wisconsin. Prescribed fire may be a viable management tool to maintain barrens and early-seral shrubland habitats. Brown Thrashers will use areas with frequent burn rotations (annual) as long as a shrub-component remains (Davis et al. 2000). Conservation and management strategies for this species should be focused in the following Wisconsin ecological landscapes: Central Sand Plains, Northeast Sands, Northwest Sands, Southeast Glacial Plains, Southwest Savanna, and Western Coulee and Ridges (WDNR 2005).

Research Needs

Because of their frequent use of farmlands, more research is needed on the Brown Thrasher’s susceptibility to agricultural chemicals. To facilitate better-informed management decisions, more information is needed on the effects of land management practices on nest predation rates (Cavitt and Haas 2000). 

Information Sources

References

Contact:

Kreitinger, K., Y. Steele and A. Paulios, editors. 2013.
The Wisconsin All-bird Conservation Plan, Version 2.0. Wisconsin Bird Conservation Initiative.
Wisconsin Department of Natural Resources. Madison, WI.

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