Small-flowered tonella (Tonella tonella) COSEWIC assessment and status report: chapter 12
Technical Summary
Tonella tenella
Small-flowered tonella – tonelle délicate
Range of Occurrence in Canada:
British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²)
Based on area encompassed by the 5 subpopulations at one site.
< 1 km² (3400 m²)
Specify trend in EO:
Unknown
Are there extreme fluctuations in EO?
Unknown
Area of occupancy (AO) (km²)
Based on an approximation of area occupied by the 5 subpopulations.
≤ 1 km² (62 m²)
Specify trend in AO:
Unknown
Are there extreme fluctuations in AO?
Unknown
Number of known or inferred current locations:
1 with 5 subpopulations
Specify trend in # :
Unknown
Are there extreme fluctuations in number of locations?
Unknown
Specify trend in area, extent or quality of habitat:
Decline
Population Information
Generation time (average age of parents in the population):
1 year
Number of mature individuals:
about 230-315 estimated at 4 sub-populations plus an unknown number at the remaining unconfirmed sub-population
Total population trend:
Unknown
% decline over the last/next 10 years or 3 generations.
N/A
Are there extreme fluctuations in number of mature individuals?
Unknown
Is the total population severely fragmented?
Yes
Specify trend in number of populations:
Unknown
Are there extreme fluctuations in number of populations?
Unknown
List populations with number of mature individuals in each Subpopulations
- unknown
- 56+
- 100-150
- 50-80
- 30
Threats (actual or imminent threats to populations or habitats)
- Housing development
- Exotic species, especially grasses
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: Common
Is immigration known or possible?
Unknown
Would immigrants be adapted to survive in Canada?
Unknown
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
Unlikely
Quantitative Analysis
N/A
Current Status
COSEWIC: Endangered
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: Met criteria for Endangered, B1ab(iii)+2ab(iii); C2a(ii).
Reasons for Designation: A small annual herb known from a single site in the Gulf Islands, British Columbia. At risk to potential development, alien species and fire management.
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