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Montana Field Guides

Sage Thrasher - Oreoscoptes montanus

Species of Concern
Native Species

Global Rank: G4
State Rank: S3B

Agency Status
PIF: 3


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Copyright by: The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, NY, all rights reserved.
General Description
The Sage Thrasher is North America's smallest thrasher with a relatively short bill and tail. Its long, melodious, mockingbird-like song, originally earned it the name of Mountain Mockingbird (Reynolds et al. 1999). Genetic work indicates this species may, in fact, be more closely related to the mockingbirds (Mimus) than to other thrashers (Sibley and Ahlquist 1984). The Sage Thrasher, considered a sagebrush obligate species, is dependent upon large, unfragmented sagebrush habitats for breeding (Reynolds et al. 1999).

For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.

Migrants arrive in Montana in late April through mid-May (Montana Bird Distribution Committee 2012). Records of adults incubating and feeding nestlings have been recorded in early June. Observations of adults feeding fledged young have been recorded from July through August.

Diagnostic Characteristics
The bill and tail of this thrasher are relatively short compared to those of other thrashers. Sexes are similar in plumage characteristics with males slightly larger than females. Adults are brownish-grey with some indistinct dark streaking on the back and crown. A dark streak through the eye separates the upper and lower lighter areas of the face. The cheek is also light with a darker line present along the sides of the throat. The bill is dark and short, and the eyes are yellow to amber in color. Underparts are generally off-white with bold dark marks (Reynolds et al. 1999).

Species Range
Montana Range

All Ranges
(Click legend blocks to view individual ranges)

Western Hemisphere Range


Range Comments
The distribution of the Sage Thrasher is dependent upon the presence of appropriate sagebrush habitat. In Montana, this species primarily occurs in the southwest, south-central, and south-eastern portions of the state.

Observations in Montana Natural Heritage Program Database
Number of Observations: 853

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density


(direct evidence "B")

(indirect evidence "b")

No evidence of Breeding
(transient "t")

(regular observations "W")

(at least one obs. "w")


(Observations spanning multiple months or years are excluded from time charts)

The Sage Thrasher is a short-distance migrant (Reynolds et al. 1999). In Montana, adults arrive on the breeding grounds from April 25 to May 15, with fall migration from July 30 to August 15.

In Montana, the Sage Thrasher breeds in habitats dominated by Big Sagebrush. Sage Thrasher abundance is positively correlated with sagebrush cover and negatively correlated with grass cover. The Sage Thrasher uses sagebrush habitats, grasslands, and other semi-arid habitats during spring and fall migration and tends to avoid areas of human habitation (Reynolds et al. 1999).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.  If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2012.  Mammals of Montana.  Second edition.  Mountain Press Publishing, Missoula, Montana.  429 pp.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
During the breeding season, eats insects primarily, with a small percentage comprised of other arthropods and some plant material. Will also eat berries and small fruits if available. This species generally forages on the ground (Reynolds et al. 1999).

Sage Thrashers are known to reject cowbird eggs (Reynolds et al. 1999).

Reproductive Characteristics
Nesting occurs soon after arrival on the breeding grounds. Nests are most commonly placed deep within or under big sagebrush or three-tip sagebrush. Nest is bulky and constructed of twigs and lined with grasses and animal fur. Clutch size averages 4-5 eggs, and eggs are incubated by both sexes. Incubation period ranges from 11-17 days. Both sexes brood and feed nestlings. Nestling period ranges from 10-14 days. Both parents continue to feed young at least one week after fledging (Reynolds et al. 1999).

The Sage Thrasher requires large, continuous stands of Big Sagebrush. Protection and conservation of large, intact sagebrush stands with high structural complexity is critical to maintaining habitats for the Sage Thrasher (Reynolds et al. 1999). The recent Greater Sage-Grouse Habitat Conservation Strategy developed for Montana may also assist in the conservation and management of other sagebrush obligates, including the Sage Thrasher.

Threats or Limiting Factors
Loss or fragmentation of intact sagebrush landscapes due to fire, residential development, or conversion to agriculture will reduce or eliminate habitat for Sage Thrashers during the breeding season (Reynolds et al. 1999).

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Citation for data on this website:
Sage Thrasher — Oreoscoptes montanus.  Montana Field Guide.  .  Retrieved on , from