Inferred decline, but magnitude unknown.Įstimated percent of continuing decline in total number of mature individuals within Inferred decline based on cumulative habitat loss and degradation within the Okanagan Valley magnitude unknown. Is there an continuing decline in number of mature individuals? There is a small possibility of unrecorded populations in adjacent habitats. An additional site in the Okanagan Valley was converted to agricultural use and is presumed extirpated, although the area has not been re-surveyed. This site is still considered extant and included in the number of locations. One site at Summerland (Okanagan Valley) is situated in an artificial rock wall within a cemetery and considered a result of movement of material by humans. There are at least 16 locations: eight in the lower Similkameen Valley and eight in the south Okanagan Valley. Limiting factors include small population sizes at occupied sites and isolation from other populations widely separated areas of unsuitable habitat and limited dispersal abilities that may prevent recolonization of new areas. A combination of wildfires, water management activities, landslides, and pesticides also threaten the species. The primary threat is the conversion of natural habitat to urban and agricultural development, and road construction and maintenance activities along transportation and service corridors. These considerations resulted in the designation of Not at Risk.
Furthermore, there is extensive potential habitat in the Similkameen and Okanagan Valleys that has not been surveyed for the species. However, overall threats to the specific rocky habitats of the species are considered to be low at present. Sites and habitats are potentially at risk from urban and agricultural development, road construction, and utility corridor maintenance activities. This species has limited dispersal ability and small population sizes within isolated rocky habitats. It requires cool, humid microhabitats beneath large rocks that enable its survival in otherwise hot and dry environments. The species has a restricted range within bunchgrass- and Ponderosa Pine-dominated ecosystems and is found only within a specific habitat within these ecosystems.
This small, rare spider is one of only two native cellar spiders in Canada.
Scientific name Psilochorus hesperus Status