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COSEWIC assessment and update status report on the American Columbo in Canada

Technical Summary

Frasera caroliniensis

American columbo
frasère de Caroline

Range of Occurrence in Canada: Ontario

Extent and Area Information

Extent of occurrence (EO)(km2)
Estimates based on all 22 historical populations and 12 current populations.
8000 km2 historically
2000 km2 at present based on extant populations

Specify trend in EO

Are there extreme fluctuations in EO?

Area of occupancy (AO) (km2
Estimate based on 12 extant populations with a maximum extent of 1 ha each
<1 km2 (12 ha)

Specify trend in AO

Are there extreme fluctuations in AO?

Number of known or inferred current locations
12 + 1 uncertain

Specify trend in #
Mainly historical decline, but 2 recent losses

Are there extreme fluctuations in number of locations?

Specify trend in area, extent or quality of habitat

Population Information

Generation time (average age of parents in the population)
7-15+ years

Number of mature individuals
Unknown but 3919 vegetative rosettes were counted in 2004 New data for 2005 indicates that there are in the order of 4200 plants including only about 70 in flower at 6 sites surveyed.

Total population trend:

% decline over the last/next 10 years or 3 generations.
Unknown overall, with some populations stable, others increasing or decreasing

Are there extreme fluctuations in number of mature individuals?
Probably not

Is the total population severely fragmented?

Specify trend in number of populations
Mainly historical decline

Are there extreme fluctuations in number of populations?

List populations with number of mature individuals in each

Threats (actual or imminent threats to populations or habitats)

  • Sites are highly disrupted by the presence of several invasive exotic plants.
  • Habitat disturbance, in the form of trails, dumping, and logging are also of concern.
  • Potential loss of three populations is anticipated due to development activities.

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
USA: Widespread but not abundant in the USA, rare (S2) in NY, nearest state to Canadian populations

Is immigration known or possible?
Extremely unlikely

Would immigrants be adapted to survive in Canada?

Is there sufficient habitat for immigrants in Canada?

Is rescue from outside populations likely?

Quantitative Analysis

(Inadequate data for quantitative analysis)


Current Status

COSEWIC: Special Concern (1993)
Endangered (2006)

Additional Sources of Information: A literature search using Frasera caroliniensis, Swertia caroliniensis, American Columbo, Inuit Knowledge, Indigenous Knowledge, Traditional Knowledge, Aboriginal Knowledge, Native Knowledge and Indian Knowledge as keywords produced no results.

Status and Reasons for Designation

Status: Endangered
Alpha-numeric code: B1 ab (ii, iii, iv, v) + 2ab(ii, iii, iv, v) C2a(i)

Reasons for Designation: A long-lived perennial with 11 to 12 extant Canadian populations. These are fragmented and restricted geographically to a highly agricultural and urbanized region that is subject to continuing habitat loss and degradation. Populations consist primarily of vegetative rosettes with only a few flowering plants produced in a given year. The spread of invasive plants within its habitat is a major threat to the persistence of the species. Further losses of populations due to site development are anticipated.

Applicability of Criteria

Criterion A: (Declining Total Population):
Not applicable. Although a 41% decline based on the loss of 9 of 22 populations has been documented, 7 of these losses were historic and most likely well beyond the 10 years or 3 generation timeframe.

Criterion B: (Small Distribution, and Decline or Fluctuation):
Meets Endangered B1 ab (ii, iii, iv, v) +2ab(ii, iii, iv, v) due to the small Extent of Occurrence and Area of Occupancy that fall below critical values, the presence of 11-12 extant populations that are highly fragmented and the continued decline in quality of habitat. This can be inferred due the presence of sites in a highly agricultural and urbanized region that has been subjected to extensive ongoing losses in forested habitats and the presence of a series of invasive plants within its habitat. Two populations have seemingly also been lost since 1989 and future losses due to site development are inferred at three other localities.

Criterion C: (Small Total Population Size and Decline):
Meets Endangered C2a(i). The total number of rosettes counted, as of 2005, was about 4200 but the majority of rosettes likely represent vegetative plants that are not mature and not ready to flower. As of 2005, an incomplete inventory from 6 of the 12 extant sites yielded only 70 flowering plants at 4 sites with the largest number at a single site being 24. It is unlikely that a single population would have more than 250 mature (flowering) plants.

Criterion D: (Very Small Population or Restricted Distribution):
Meets Threatened D2 due to the very small area of occupancy comprising <1 km2 from which can be inferred that stochastic events could impact the populations. The populations also occur within a highly urbanized region where habitat degradation and loss can be expected to continue. Site development at three localities may also result in population losses.

Criterion E: (Quantitative Analysis):
Not available.