Sage Thrasher

Nesting habitat of this Endangered species has been lost to urban and agricultural development.

Province of British Columbia Ministry of Environment, Lands and Parks settlement. It is estimated that 60 per- nesting sites in the south Okanagan cent of the original sagebrush-steppe in have been developed for farming or adjacent Washington state has been de- housing and no longer support nesting stroyed. Habitat loss in Washington thrashers. The status of the Sage Why are Sage Thrashers could also jeopardize these birds by fur- Thrasher in British Columbia is indeed at risk? ther isolating British Columbia habitats precarious. ritish Columbia’s small nesting and reducing the number of birds that population of Sage Thrashers is lim- spill over into the province. What do they look like? ited by availability of suitable habitat age Thrashers are slightly smaller B in the south Okanagan. Near Oliver What is their status? than an American Robin, with a and Penticton, development of or- n British Columbia, Sage Thrashers brownish-grey back, buffy white un- chards and vineyards has destroyed are on the BC Environment Red List S derparts heavily streaked with some habitat where thrashers nested in (species being considered for legal brown, yellow eye, robin-like bill, white the 1920s. Prime sagebrush habitat has I designation as Endangered or tips on the outer tail feathers and two been lost to alfalfa production and other Threatened) and considered to narrow, white bars on the wings. Males areas have been degraded by heavy live- be “critically en- and females have similar mark- stock use, or by range rehabilitation dangered” by the The Sage ings. Its general colouring pro- projects such as sagebrush mowing, Conservation Data Thrasher is vides good camouflage in burning, or spraying with herbicides. Centre. They are sagebrush landscapes. It is a secre- Increasing human populations and designated as En- designated as tive bird of dense sagebrush thick- more intensive land use continue to dangered by the Endangered ets and prefers running to flying threaten the remaining 50 percent of Committee on the when searching for food. It is Sage Thrasher habitat in the south Status of Endan- by . more often heard than seen. Okanagan and Similkameen valleys. gered Wildlife in Birders wishing to add this spe- Residential, or other developments, are Canada (), and listed as a Spe- cies to their British Columbia list should of particular concern in the Richter Pass cies of Concern in Washington. visit sagebrush stands in the south and White Lake areas. Like most birds in British Columbia, Okanagan-Similkameen area in late As with most birds, Sage Thrashers the Sage Thrasher, its nests and eggs are May or June, preferably with guidance suffer some losses due to nest destruc- protected under the Federal Migratory from local naturalists who know the tion by ground predators, raptor preda- Bird Protection Act and the provincial whereabouts of this sparsely distributed tion on naive fledglings, human distur- Wildlife Act. However, no habitats bird. Extreme care must be taken not to bance, or other factors. Where habitats critical for survival of the species in disturb nesting birds. Please do not ap- are suitable, enough young are normally British Columbia are currently pro- proach the birds; listen and view from a produced to balance these losses, tected against loss or degradation. distance of 25 metres or more. and thrasher pop- Typical of many birds at the ulations do not de- No habitats northern limit of their range, Sage What makes them unique? cline. Loss of habi- critical for Thrasher numbers in British he Sage Thrasher’s scientific name, tat, however, per- Columbia fluctuate from year Oreoscoptes montanus, means manently reduces the survival to year, with some sites being oc- “mimic of the mountains” but, un- the number of cupied only rarely. Recently, T like several members of the of the species thrashers that any however, there also appears to thrasher-mockingbird family, Sage area will support. in British have been a substantial decline in Thrashers do not mimic other birds. In the United Columbia the nesting population. At its his- Their song has been described as “ec- States, large areas torical high in the 1930s, or ear- static” and “energetic” and inspired of Sage Thrasher are currently lier, the spring population in Brit- American ornithologist, A.C. Bent, to nesting habitat protected. ish Columbia may have reached call the Sage Thrasher “the poet of have been lost due 30 or more pairs nesting at up to the lonesome sagebrush plain.” The to livestock range six sites. Only four to ten pairs territorial song is a long series of alteration, cultivation of crops, strip have been seen in recent years, at only warbled phrases lasting up to 2.5 mining, reservoir flooding, and land one or two sites. At least two former minutes, usually made with head held high, from the top of a big sage. Call ally positioned where sagebrush foliage cated. In good habitat, nesting territo- notes include a sharp “chuck” and a provides some shade, the enterprising ries are about 5 hectares in size. high “churr.” thrashers sometimes build shade cano- Sage Thrashers usually lay four or True to their name, Sage Thrashers pies over them. five eggs. These are about 2.5 cm long, throughout their range prefer relatively smooth and glossy, with a medium to dense stands of tall sagebrush for nest- How do they reproduce? light blue ground colour that is boldly ing. In the United States, nests are some- pon arrival from their winter range spotted and blotched with reddish- times built in other shrubs associated in April or May, males select suitable brown. The eggs, incubated by both with sagebrush, including rabbitbrush, sagebrush stands where they sing sexes, hatch in about 15 days; nestlings antelope-brush, and juniper. In British U from the tops of tall shrubs to attract fledge about 13 days after hatching. The Columbia, exceptions to sagebrush for females and to let other males know the total nesting period, including egg-lay- nesting involved a nest in a peach tree in territory is occupied. In British Colum- ing, is about 32 days. a newly planted bia, nesting may begin in late May Broods of one to five young have orchard, and a or early June, reach a peak later in been reported in British Columbia. nest in a haw- Sage Thrashers June, and is largely finished by More intensive studies in the United thorn tree at prefer dense mid-July. Most Sage Thrashers in States conclude that about two young White Lake. the Okanagan migrate south in are successfully fledged per nesting at- Sage Thrasher stands of late August or early September. tempt. In the United States, where Sage nests are bulky tall sagebrush Nests are mostly 15 to 36 centi- Thrashers frequently produce two structures that metres above the ground; occa- broods each summer, the male is be- require sturdy for nesting. sionally they are built on the lieved to feed the newly fledged young shrubs for sup- ground under thick brush. The for a few days while the female incubates port. They are made of coarse sagebrush woody nests of Sage Thrashers persist the second clutch. twigs, rootlets and plant stems, and for a year or more, providing a reliable Although nesting information for lined with fine grasses, bark-shreds, and indication of breeding occurrence and British Columbia is limited, most livestock hair. Although nests are usu- habitat selection long after they are va- thrashers here seem to have only one brood, which coincides in timing with the southern Similkameen and Present range of the Sage Thrasher the second brood of birds that nest far- Okanagan valleys, an area considerably in Canada and the United States ther south. This suggests that some less than one percent of the province. Breeding range Wintering range thrashers may move into the province Although this species has a wide range after a failed first attempt at nesting in outside British Columbia, this range ex- Washington. tends only barely into the province. Nesting has been documented from the What do they eat? United States border north to lthough largely insect-eaters, Sage Penticton, including Osoyoos Lake, Thrashers also take fruits and Kilpoola Lake, Chopaka, Richter Pass, berries when available. Food habits Oliver, White Lake, and West Bench. A of this species have not Sage Thrashers been well studied in British Co- Sage have also been re- lumbia, but observations in the Thrashers ported during the United States indicate that breeding season ground-dwelling beetles, grass- nest regularly in suitable nest- hoppers, crickets, and ants are im- only in the ing habitat near portant items in the nesting sea- Vernon, Cache son. Other invertebrates taken in- southern Creek, and Kam- clude caterpillars, weevils, Similkameen loops and may leafhoppers, flies, and spiders. occasionally nest Sage Thrashers also show a fond- and in those areas. As ness for berries, including cur- Okanagan with many species rants, gooseberries, blackberries, of birds, vagrants arrive in May. Sightings of Sage Thrash- and Saskatoon berries. valleys. are sometimes ers north of their usual south Okanagan seen outside the nesting range have mostly been in April, Where do they live? usual breeding areas. Such records for and probably involve birds that over- age Thrashers nest only in the dry, the Sage Thrasher include Vancouver shoot the traditional breeding areas. sagebrush-dominated plains and Island, Revelstoke, the Fraser River This behaviour frequently occurs in intermountain basins of western delta, 100 Mile House, and Creston. birds, and has survival advantage for the S North America. Populations have Sage Thrashers are migratory and oc- species (if not the individual) by ensur- declined in many areas because of habi- cur in British Columbia only in spring ing that any new peripheral habitats are tat loss through urban development and and summer. Our small population mi- discovered. agriculture. The species breeds from ex- grates at least 1500 kilometres to its win- In late summer, autumn, and winter, treme south-central British Columbia, ter habitats. The earliest provincial Sage Thrashers use a variety of scrub, central Idaho and south-central record is April 4, but most individuals desert, and farmland habitats. In the Montana, south to southern nesting season, however, they are al- Nevada, northeastern Arizona, Present breeding range of the Sage Thrasher most entirely associated with stands of and northwestern New Mexico, in British Columbia sagebrush, but not any kind of and east to eastern Colorado and sagebrush will do. The shrubs need to be Wyoming. They also breed tall (preferably 1 metre or more) and locally in southern Alberta and sturdy enough to support the bulky southwestern Saskatchewan. The thrasher nests. The stands must be winter range, largely south dense enough (15 to 40 percent ground of the breeding range, includes cover) to provide hiding cover and Arizona, New Mexico, Texas, shade. Some cattle grazing may be ben- southern California, and north- Kamloops eficial because the thrashers like areas ern Mexico. with fairly open ground under tall In British Columbia, Sage shrubs. Heavy livestock use, though, Thrashers nest regularly only in can damage the sagebrush, and decrease the native perennial grasses which cies and habitats led to formation of the enhancement of sagebrush stands are thrashers prefer. South Okanagan Conservation Strategy also included. In British Columbia, sagebrush is (SOCS) by the Nature Trust of British To keep the Sage Thrasher as a mostly limited to the south Okanagan Columbia, BC Environment (Wildlife breeding bird in Canada, a national and Similkameen valleys, the Thomp- Branch), and other cooperating groups. recovery team was formed in 1993. As son Valley from Spences a result of their research, the Bridge to Pritchard, and the team is recommending set- Fraser Valley from Lytton ting up three separate con- to the Chilcotin River. Only servation areas, each pro- one Sage Thrasher nest viding habitat for at least ten has been found in the pairs of Sage Thrashers. Thompson or Fraser River These conservation areas areas, even though some should be at least 200 ha sagebrush stands look suit- in size, with adequate big able and thrashers have oc- sage for nesting and good casionally been sighted perennial grass cover. More there. Reasons for this are than one site is needed be- not known. cause disasters like range Even in the south fires, not uncommon in Okanagan, where Sage this area, can wipe out a sin- Thrashers do nest, some gle nesting area. One such sagebrush stands are too site was burned in a 1994 small, too sparse, or too wildfire. short (young) to be useful Despite the precarious for thrasher nesting. At status of this bird in British most, only a few hundred Columbia, no habitats have hectares of suitable sage- yet been protected or brush habitat is available in managed specifically for British Columbia. Some of it. Without such protection, these areas are Crown lands, nesting by Sage Thrashers is others are privately owned; likely to become a thing of     livestock grazing is the ma- Steve Cannings photo the past in British Colum- jor land use on all of them. bia. Surely we owe it to this More intensive surveys are underway The SOCS commissioned a Status songster of the sage, and the other rare to evaluate the quality of sagebrush Report and a Management Plan for species which share its habitat, to pro- stands in the traditional nesting areas, the Sage Thrasher in British vide for their and to map the occurrence of sagebrush Columbia, which were funded by The goal is to set future, which in adjacent areas. the World Wildlife Fund and by up three separate is also our fu- the BC Environment Habitat ture. What can we do? Conservation Fund. These pro- conservation The public he arid shrub-grass environments vide a basis for more active man- areas, each is urged to of the south Okanagan and agement and protection of Sage become more Similkameen valleys are among Thrasher habitats. Key habitats of providing familiar with T Canada’s most endangered habitats. the present breeding population the plight of habitat for at Species entirely or largely restricted are now fairly well known, and the Sage to these dry grasslands include the Management Plan provides least ten pairs. Thrasher and the Night Snake, White-tailed recommendations for protecting other British Jackrabbit, Nuttall’s Cottontail, Brew- them by land acquisition or Columbia “rarities,” and to support er’s Sparrow, Grasshopper Sparrow and through covenants with landowners. programs for their conservation. Sage Thrasher. Concern for these spe- Suggestions for management and                 . Rhonda Millikin photo

,      .        . Rhonda Millikin photo Bill Harper photo

      , : Wildlife Branch BC Environment Ministry of Environment, Lands and Parks 780 Blanshard Street Victoria, British Columbia V8V 1X4

    Corporate Resource Inventory Initiative (Province of British Columbia)

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