Scientific Name: Polites sonora
Taxonomy Group: Arthropods
Range: British Columbia
Last COSEWIC Assessment: November 2016
Last COSEWIC Designation: Not at Risk
SARA Status: Schedule 1, Special Concern
Image of Sonora Skipper
Canadian specimens of the Sonora Skipper do not fit the description of any of the three known subspecies of Polites sonora, so it is impossible to determine, based on the existing literature, whether Canadian populations belong to one of those subspecies. The Canadian populations may be an undescribed subspecies.
The Sonora Skipper in Canada is a small butterfly with a wingspan of 25 to 30 mm. The upper side of the wings is a combination of rusty orange and brown with blackish borders. The underside of the forewings has a black patch at the base, tawny and pale areas in the centre, and an olive green border. The ventral surface of the hindwings is olive green with a distinct semicircular band of pale spots. Males have a distinctive elongated black spot, called a stigma, on the forewing. Females are similar to males, except that they lack the stigma and are usually larger. The eggs are very light green and spherical in shape with a flattened base. They are roughly 1 mm in diameter. Mature caterpillars have a black head and greyish-green body with many fine black hairs, called setae. At maturity, caterpillars have a body length of 6 mm.
Distribution and Population
The species is widely distributed in western North America from extreme southwestern British Columbia south to Baja California and east to Wyoming and Colorado. The Canadian distribution is limited to the Cascade Mountains, from E.C. Manning Provincial Park east to Crater Mountain and the Thompson Plateau immediately south of Princeton. Additional suitable habitat that has not been searched (because it is not accessible by road) likely occurs in this portion of southern British Columbia. In British Columbia, the Sonora Skipper is currently confirmed at six sites. In the past, the species was known from three precisely defined locations, two on Crater Mountain and one at Twenty Minute Lake in Manning Provincial Park. A 1989 record exists from an undefined location in Manning Park that may or may not be Twenty Minute Lake. The Sonora Skipper was also known from one or two imprecisely defined locations in the “Hope Mountains,” a historical term referring to the Cascade Mountains between Hope and Princeton. Fieldwork in 2003 resulted in two additional locations for the Sonora Skipper: one in the Wolfe Creek valley south of Princeton and another in the Placer Creek valley east of Manning Provincial Park. There are no large populations of the Sonora Skipper in Canada. Roughly 30 adults were observed in 2003, and all past collections are of one or a few individuals. The sizes and trends of individual Canadian populations are unknown.
Known habitats for Sonora Skipper are moist, grassy openings in mountainside forests and moist logged areas, particularly along rivers. In British Columbia, the species shows some ability to make use of some habitats that result from human alteration, such as grassy roadside areas, agricultural meadows, and small logged areas, but only if these habitats are moist. The detailed habitat requirements of the Sonora Skipper are unknown, but it is significant that this species does not occur in all habitat that appears suitable.
Very little is known about the biology of this species. However, like other butterflies, the Sonora Skipper undergoes complete metamorphosis, with egg, larva (caterpillar), pupa (chrysalis), and adult stages. It completes its life cycle in one year. Each stage has specific resource requirements. The food plants used by caterpillars are unknown, but one or more grass species are the likely food plants in Canada. The nectar species of the adults are also unknown. Adults have been found from June 21 to August 13, which partially coincides with the mating season, which usually takes place during the short adult flight period.
The most significant limiting factor for the Sonora Skipper is likely the limited availability of moist, grassy habitat without tree cover in an area where coniferous forests predominate. What little grassland exists is predominantly too arid for this species. Possible threats to Sonora Skipper habitat are intensive grazing, natural succession of open areas to forest, and road construction. Logging has increased the available habitat in one known location, but future plantation growth will render the habitat unusable if grassy openings are not maintained. Wildfires or controlled burns, although likely to increase habitat availability, may also be a threat to existing populations.
South Okanagan Invertebrates at Risk Recovery Team
Orville Dyer - Chair/Contact - Government of BC
Phone: 250-490-8244 Send Email
Jennifer Heron - Chair/Contact - Government of BC
Phone: 604-222-6759 Fax: 604-660-1849 Send Email
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
9 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Management Plans (1 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2006 (2006)2006 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
Recovery Document Posting Plans
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