BC Conservation Data Centre: Conservation Status Report
Erynnis propertius
Propertius Duskywing
| Scientific Name: | Erynnis propertius |
|---|---|
| English Name: | Propertius Duskywing |
| Provincial Status Summary | |
| Status: | S2 |
| Date Status Assigned: | March 31, 2013 |
| Date Last Reviewed: | January 28, 2020 |
| Reasons: | This species is common within the Garry oak ecosystems, yet only 5% of those ecosystems remain (GOERT 2007). |
| Range | |
| Range Extent: | EF = 5,000-200,000 square km |
| Range Extent Comments: | The Garry Oak and associated ecosystems occur in fragmented patches throughout the southern half of Vancouver Island and the adjacent gulf islands. |
| Area of Occupancy (km2): | U = Unknown |
| Area of Occupancy Comments: | The Garry Oak and associated ecosystems occur in fragmented patches throughout the southern half of Vancouver Island and the adjacent gulf islands. Most of this ecosystem is within private land ownership and being converted for urban/agricultural land development. |
| Occurrences & Population | |
| Number of Occurrences: | D = 81 - 300 |
| Comments: | This species is usually present within Garry oak and associated ecosystem habitats, although usually not present where there has been extensive landscaping below a Garry oak tree. Found within Garry oak and associated habitats throughout southern Vancouver Island and the gulf islands. Documented records show greater than 40 locations throughout this region, and likely more occurrences (Royal BC Museum database; UBC Spencer Entomological Museum database). |
| Number of Occurrences with Good Viability / Ecological Integrity: | C = 4 - 12 |
| Comments: | This species is known to occur in numerous protected areas and habitats with Garry oak ecosystem attributes. Garry oak (Quercus garryana) is the larval foodplant. The viability at each of these occurrences has not been assessed. |
| Number of Occurrences Appropriately Protected & Managed: | D = 13 - 40 |
| Comments: | Propertius duskywing is protected within numerous federal, provincial, regional and municipal areas. Protected areas include Government House, Rocky Point and Gulf Islands National Park Reserve, Mill Hill Capital Regional Park, Cowichan Garry Oak Preserve; Government House; Helliwell Provincial Park; Mt. Tuam; and Mt. Tzuhalem Ecological Reserve (RBCM database; UBC Spencer Entomological Museum database). |
| Population Size: | U = Unknown |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | AB = Very high - high |
| Comments: | The Garry Oak and associated ecosystems occur in fragmented patches throughout the southern half of Vancouver Island and the adjacent gulf islands. Most of this ecosystem is within private land ownership and being converted for urban/agricultural land development. Additional threats to the species include Btk spray (to control Gypsy Moth infestation (Lymantria dispar)); invasive species encroachment into Garry oak ecosystems; raking/management of habitat under the Garry oak trees (species is thought to overwinter in the leaves/duff under Garry oak trees), inadvertant trampling by recreational users; grazing of Garry oak saplings by ungulates. Additional threats include habitat destruction; invasive species (invasive vertebrates, invertebrates, shrubs, grasses and forbs); habitat fragmentation; changes in native vegetation composition from altered fire regimes; recreation; demographic collapse; mowing; changes to hydrology; climate change; re-introduction of fire; livestock grazing; cutting or handpulling of invasive plants; maintenance activities; herbivory; pesticides; landscaping with non-native plants; and marine pollution. |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | F = Decline of 10-30% |
| Comments: | The Garry Oak and associated ecosystems that this species relies on occur in fragmented patches throughout the southern half of Vancouver Island and the adjacent gulf islands. Most of this ecosystem is within private land ownership and being converted for urban/agricultural land development (GOERT 2007). |
| Long-Term Trend: | BC = Decline of 70-90% |
| Comments: | The rate of decline of the Garry Oak and associated ecosystems within BC that this species relies on has been significant in the past one hundred years. |
| Other Factors | |
| Intrinsic Vulnerability: | B=Moderately vulnerable |
| Environmental Specificity: | A=Very narrow. Specialist or community with key requirements scarce. |
| Comments: | Propertius duskywing larval host plant is Garry oak (Guppy and Shepard, 2001), and without this tree the species cannot complete its life cycle. This species relies on the Garry Oak tree as a foodplant (Guppy and Shepard, 2001), and the substrate under the tree is equally important for overwintering purposes. The tree is common within the southern half of Vancouver Island and the gulf islands, and often planted in urban landscapes/private yards. But the area under the tree is often modified (leaves are raked, non-native plants are grown) and this substrate is not appropriate for sustaining the species throughout its overwintering stage. |
| Other Rank Considerations: | The rate of decline of the Garry Oak and associated ecosystems within BC has been significant in the past one hundred years. |
| Information Gaps | |
| Research Needs: | Research is required to more accurately quantify specific habitat requirements including food plant density and patch size. Species' dispersal capabilities, reproductive success and population viability need to be assessed; study of the potential impacts of predation, parasitism, climatic variation, small population size, and population isolation is also needed. Research is required to assess the potential threats to habitat from invasive weeds, adjacent property management and wild fire. More specific research is required to assess the use and need of duff under the Garry oak tree, and the use of this habitat as overwintering habitat for the butterfly, and the effects of clearing this habitat on the species. Research is also required to assess potential threats from pesticide use and heavy livestock grazing on all life stages. |
| Inventory Needs: | Inventory of butterflies in the Garry oak ecosystems is needed. Inventory of potential habitat, population size and distribution is incomplete and requires additional surveys. Monitoring of population parameters including fluctuations in size, emigration, recruitment, persistence, dispersal distance, etc. is not available. A long term monitoring program needs to be established and implemented. |
| Stewardship | |
| Protection: | Provisions for species specific management should be incorporated into all park planning documents. Creation of best management practices guidelines for private landowners, including urban homeowners with patches of Garry oak on their property. |
| Management: | This species would benefit from specific management within protected areas, best management practices guidelines for urban landowners. |
| Version | |
| Author: | Heron, J. |
| Date: | November 22, 2012 |
| References | |
|
GOERT. 2007. Garry Oak Ecosystems Recovery Team Website. Available: http://www.goert.ca/orphs/welcome.htm (accessed January 2007).
|
|
|
Royal British Columbia Museum (RBCM). 2006. RBCM Lepidoptera Collection.
|
|
|
University of British Columbia. 2006. Spencer Entomology Museum's Butterfly Collection Database.
|
|
Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2012. Conservation Status Report: Erynnis propertius. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed May 9, 2025).