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 )

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

  1. unknown
  2. 56+
  3. 100-150
  4. 50-80
  5. 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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