Gold-edged gem (Schinia avemensis) COSEWIC assessment and status report: chapter 11
Technical Summary
Schinia avemensis
Gold-edged Gem – Héliotin d'Aweme
Range of Occurrence in Canada:
Prairie Ecological Area, southwestern Manitoba to southeastern Alberta (MB, SK and AB)
Extent and Area Information
Population Information
- Spirit Dunes, MB – 500-5,000 est.
- Burstall SK (unknown)
- Bindloss & Pakowki AB 200-1,000 est.
Threats (actual or imminent threats to populations or habitats)
Stabilization of active sand dune habitat by native and introduced vegetation due to largely natural processes, probably accelerated since settlement due to suppression of wildfires.
Rescue Effect (immigration from an outside source)
Quantitative Analysis
Current Status
COSEWIC: Endangered (2006)
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: B2ab(iii)
Reasons for Designation: This moth is a habitat specialist that needs dunes or blow-outs with populations of its sole larval host plant. It is known from only two small populations in Canada and two in the United States. Large-scale decline in active dune habitat over the past 100 years has likely resulted in a corresponding reduction in the moth. Only very small, scattered, isolated patches of suitable habitat, totalling approximately 6 km², remain. They are threatened by habitat loss in the form of stabilization of active dunes by both native and introduced vegetation and by overgrazing of their larval host plant, which severely impacts small, isolated populations of the moth. The closest population of the moth in the United States is about 1,200 km to the south in Colorado, so immigration of individuals into the Canadian population is not possible.
Applicability of Criteria
- Criterion A: (Declining Total Population): Not applicable, no decline data
- Criterion B: (Small Distribution, and Decline or Fluctuation): Although the extent of occurrence is large, the area of occupancy is smaller than 500 km² (known AO is approximately 1.5 km²; max potential AO is approximately 6 km²) – B2 the total population is severely fragmented with the species known to occur as 2 populations spread over 5 sites – (a) the area and quality of suitable habitat are continuing to decline – (b)(iii) but there is no evidence for extreme fluctuations
- Criterion C: (Small Total Population Size and Decline): not applicable, no decline data and insufficient information on population structure
- Criterion D: (Very Small Population or Restricted Distribution): Meets Threatened under D2. The total population occurs at a restricted number of locations (2 populations at 5 sites) and the area of occupancy is very small and restricted (max of approximately 6 km²) such that the species appears to be prone to the effects of human activities and stochastic events.
- Criterion E: (Quantitative Analysis): not applicable, no data.
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