E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Oreoscoptes montanus (Townsend, 1837)
Sage Thrasher
Family: Mimidae

Species account author: Jamie Fenneman

Photo of species

© Scott Streit  Email the photographer   (Photo ID #11847)

Distribution of Oreoscoptes montanus in British Columbia.
(Click on the map to view a larger version.)
Source: Distribution map provided by Jamie Fenneman for E-Fauna BC

Species Information

The upperparts (back, scapulars, wings, tail) are uniformly light greyish-brown, sometimes with faint darker streaking on the upper back. The tail feathers are slightly darker than the rest of the upperparts, with small white spots at the tips of all but the centralmost pair of feathers. The wing coverts are narrowly tipped with dull white, forming two narrow wing bars. The underparts are dingy-white with a buffy wash on the sides, flanks, and undertail coverts and narrow blackish streaks and spots on the breast, sides, flanks, and belly. The head is largely greyish-brown, similar in tone to the upperparts, with an indistinct pale greyish-white eyebrow, pale greyish lores, buffy-brown auriculars, and dull whitish or greyish-white malar region and throat (separated by a narrow dark submalar stripe). The plumage becomes heavily worn by mid summer, during which time the streaks on the underparts become reduced (almost absent in some individuals) and the head pattern becomes duller and less strongly contrasting. The relatively short, pointed, streaight bill is dark or dusky with a pale greyish or horn-coloured base to the lower mandible, the iris is yellow, and the legs and feet are greyish with yellowish soles.

This plumage is held into the fall (September) of the first year. Juveniles are very similar in plumage to adults, but have somewhat paler upperparts with more pronounced dark streaks on the head, back, scapulars, and rump.

Total Length: 21-22 cm
Mass: 39.5-50 g

Source: Reynolds et al. (1999); Sibley (2000)



The Sage Thrasher is a fairly distinctive and easily identified species, particularly given its narrow habitat preferences. It is most likely to be confused with adult and juvenile Northern Mockingbird, a regular vagrant to British Columbia (and extralimital breeder) that could occur in habitats that are frequented by Sage Thrashers. Adult Northern Mockingbirds should be easily distinguished, however, by the large white flashes in the wings, extensive white outer tail feathers, paler grey upperparts and head, and unstreaked underparts (although most worn Sage Thrashers in mid- to late summer have largely lost the dark streaking on the underparts). Juvenile Northern Mockingbirds are overall buffier than adults and have faint darker spotting on the breast, and are thus more similar to Sage Thrasher. Like adults, however, the prominent white patches in the wings and tail should serve to easily distinguish these individuals from Sage Thrasher.

The male’s song is a prolonged, soft warble of mellow, rolling or churring whistled notes that changes periodically in tempo but generally does not change in pitch; accented phrases are sometimes interspersed throughout the song. The song is often relatively quiet and can be easily overlooked. Calls include a low chup or chuck (similar to Hermit Thrush, but harder) and a sweet, high wheeurr. The Sage Thrasher occasionally mimics the calls of other bird species, including the Western Meadowlark, Brewer’s Sparrow, and Horned Lark.

Source: Reynolds et al. (1999); Sibley (2000)

Breeding Ecology

Pair formation occurs on the breeding grounds within a week of the arrival of females. Aside from song, the male Sage Thrasher also uses several courtship displays that are designed to both attract a mate as well as establish territorial boundaries. Males occasionally fly in undulating circles low over sagebrush habitat while singing, occasionally at heights of up to 8 m or dipping as low as the tops of the sagebrush. Upon alighting following these song flights, the male commonly raises one or both wings and flutters them for several seconds while continuing to sing.

Both sexes contribute to the construction of the nest, which is built within 1-2 weeks of pair formation. The nest is placed in a low shrub (typically a sagebrush, but sometimes placed in other species such as rose, Saskatoon, cherry, snowberry, etc.), and is usually placed in one of the larger, denser shrubs within the territory. Nest heights range from 0.1-1.5 m; some pairs may nest on the ground, although this has not been confirmed in British Columbia. The nest is a bulky cup (18-20 cm wide and ~10 cm deep) of coarse twigs and strips of bark that is lined with grasses, rootlets, hair, and fur; some nests are partly concealed by an overhanging canopy of branches.

A single clutch of 4-5 (7) eggs is laid between late May or early June and mid-July and is incubated by both sexes for 11-17 days before hatching. The smooth, glossy eggs are deep, rich blue or greenish-blue and are boldly spotted with large, well-defined brown, reddish-brown, buffy, or grey markings that are often concentrated around the larger end (commonly forming a “wreath”). There are no instances of Brown-headed Cowbird parasitism of Sage Thrasher nests in British Columbia, and it is an extremely rare host elsewhere in North America. Eggs are present in B.C. between late May and late July.

The nestlings are fully altricial and largely naked to sparsely downy upon hatching, with dark brown skin and tufts of blackish or dark bluish-black down on the head and body; the mouth cavity is bright orange to yellowish. The young remain in the nest for 10-14 days before fledging, during which time they are tended by both parents. After fledging, the young remain with and are tended by both parents for an additional week before dispersing and becoming fully independent. Nestlings and dependent fledglings have been recorded in British Columbia between mid-June and mid-August.

Source: Baicich and Harrison (1997); Campbell et al. (1997); Reynolds et al. (1999)
Foraging Ecology

This species forages almost exclusively on the ground. Prey is picked directly off the ground or gleaned from low hanging branches, and some prey items are even dug out of the ground. The diet consists largely of insects (especially ants and ground beetles) and spiders, particularly during the breeding season, although berries and fruits are also consumed when they are available. When consuming berries and fruits, the Sage Thrasher often picks them directly from the branches of small bushes, sometimes merely breaking the skin to sip the juices.

Source: Reynolds et al. (1999); Gebauer (2004)


True to its name, the Sage Thrasher is closely associated with extensive areas of large, dense sagebrush in the arid shrub-teppes of the south-central interior. Such habitats are often maintain through prolonged overgrazing, which removes much of the grass cover but allows for the establishment of dense stands of mature sagebrush (which are avoided by cattle). Virtually all records of breeding and territorial individuals in British Columbia have been from such habitats. Vagrants are found in a wider variety of habitats, including dykes, estuaries, coastal beaches, hedgerows, and agricultural habitats.

Source: Campbell et al. (1997); Reynolds et al. (1999)


Global Range

Breeds from extreme southern British Columbia, extreme southeast Alberta, and southwestern Saskatchewan south through the western United States to eastern California, northern Arizona, and northern New Mexico (east to western South Dakota and eastern Colorado). Winters from southern California, central Arizona, central New Mexico, and central Texas south through northern and central Mexico.
BC Distribution

Rare to uncommon, and highly local, in the southern Okanagan and Similkameen Valleys of the south-central interior, ranging north regularly in small numbers to Okanagan Falls (White Lake) and west to Keremeos. This species may also nest occasionally in the Fraser-Thompson Basin, as evidenced by the discovery of an old nest near Cache Creek in 1990.

Migration and Vagrancy
Early spring migrants sometimes occur in the south-central interior as early as early April, but the bulk of the population does not typically arrive until May or even early June. Fall migrants depart B.C. through August, with occasional individuals lingering in the Okanagan or Similkameen Valleys as late as late September.

This species is a casual spring and summer vagrant elsewhere across southern B.C., including Vancouver Island, the southern mainland coast, the northern Okanagan Valley (Vernon), the Thompson and Fraser Basins of the south-central interior, and the Creston Valley of the southeastern portion of the province. Most vagrants are recorded on the south coast during April and May, but vagrants across the southern interior occur primarily from May through July. Northernmost records of vagrants (all spring migrants) are from the 100 Mile House and Revelstoke areas. This species is accidental in B.C. as a fall vagrant, with only a single record for the Lower Mainland.

Source: Campbell et al. (1997)


Population and Conservation Status

The Sage Thrasher has always been a scarce and peripheral species in British Columbia, and remains so today. Its population in the province tends to vary from year to year, with very few individuals observed during some years. Similarly, locations of breeding pairs tend to change yearly, with pairs occurring at certain sites only during one breeding season while at other more perennial breeding locations pairs can be scarce or even absent during some years. Recent estimates of the provincial breeding population range from 5-12 pairs, but historical maximum counts may have been as high as 30 pairs. Several former breeding locations in the Okanagan Valley have been lost to agricultural and suburban development, and most birds now occur in only a small number of locations (White Lake, Richter Pass, southern Similkameen Valley south of Keremeos). Given the declining trend in both available habitat and the number of breeding birds, as well as the small size and peripheral nature of the provincial population, this species is classified as red-listed (Endangered) by the B.C. Conservation Data Centre (CDC). Populations elsewhere in Canada (Alberta, Saskatchewan) are also small and peripheral, and the species is classified as a federally “Endangered” species by COSEWIC (Committee on the Status of Endangered Wildlife in Canada).

Source: Campbell et al. (1997); COSEWIC (2000)


This species is monotypic, with no recognized subspecies. This is the only species in the genus Oreoscoptes, which is much more closely related to the mockingbirds (Mimus) than it is to the thrashers (Toxostoma).

Source: Reynolds et al. (1999)

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
NativeS1BRedE (Nov 2010)
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Range and Status Information Links

Additional Photo Sources

General References

Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 2023-09-24 12:25:05 PM]
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