Small-mouthed salamander (Ambystoma texanum) COSEWIC assessment and status report: chapter 12

Technical Summary

Ambystoma texanum

Small-mouthed Salamander – Salamandre à nez court

Range of Occurrence in Canada:

Ontario

Extent and Area Information

Extent of occurrence (EO)(km²):

[Area of Pelee Island as given in the report: 4,262ha] 43 km²

Specify trend in EO:

Stable

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km²):

[estimate 1 km² for each breeding site in consideration of dispersal abilities of the salamanders and available terrain] 5 km²

Specify trend in AO:

Decline

Are there extreme fluctuations in AO?

No

Number of known or inferred current locations:

3

Specify trend in #:

Decline

Are there extreme fluctuations in number of locations?

No

Specify trend in area, extent or quality of habitat:

Decline

Population Information

Generation time (average age of parents in the population):

3 yrs

Number of mature individuals:

Unknown

Total population trend:

Unknown

 % decline over the last/next 10 years or 3 generations.

Highly probable

Are there extreme fluctuations in number of mature individuals?

[other species of Ambystoma have fluctuating population sizes]

Is the total population severely fragmented?

No

Specify trend in number of populations

Are there extreme fluctuations in number of populations?

No

List populations with number of mature individuals in each:

unknown

Threats (actual or imminent threats to populations or habitats)

  • very limited distribution in Canada
  • environmental degradation
  • modified drainage patterns
  • other habitat destruction

Rescue Effect (immigration from an outside source)

Status of outside population(s)?

USA: N5
Alabama (S3), Arkansas (S5), Illinois (S5), Indiana (S4), Iowa (S3), Kansas (S5), Kentucky (S5), Louisiana (S5), Michigan (S1), Mississippi (S5), Missouri (S?), Nebraska (S1), Ohio (S?), Oklahoma (S5), Tennessee (S5), Texas (S5), West Virginia (S1)

Is immigration known or possible?

No

Would immigrants be adapted to survive in Canada?

Yes

Is there sufficient habitat for immigrants in Canada?

Yes

Is rescue from outside populations likely?

No

Quantitative Analysis

Not Applicable

Other Status

  • COSEWIC: Special Concern (1991)
  • Ontario: S1

Status and Reasons for Designation

Status: Endangered Alpha-numeric code: [B1ab(ii,iii,iv)+2ab(ii,iii,iv)]

Reasons for Designation: This salamander is restricted solely to Pelee Island in Canada. The extent of occurrence is only 40 km² (effectively the total area of Pelee Island). It occupies only three extant breeding sites and surrounding remnant forested habitat with total area of occupancy equalling not more than 5 km². It has exhibited declines in area, extent and quality of habitat, and in the number of locations on the island where it may be found. Threats to its continued existence include loss of wetland breeding sites and modified drainage patterns.

Applicability of Criteria

Criterion A: Insufficient information to calculate precise numbers of individuals.

Criterion B: Qualifies for Endangered B1,2 a, bii,iii,iv. Area of Occupancy is less than 500 km² and fewer than 5 populations currently exist. There has been decline in Area of Occupancy, extent of habitat and numbers of populations due to the loss of breeding sites at Girl Guide Pond and North End Woods. Furthermore, extreme fluctuations in numbers of mature individuals are well documented in other species of Ambystoma and considered highly probable in A. texanum.

Criterion C: May qualify for Endangered C2b as it is estimated that fewer than 1,000 adults exist on Pelee Island, there has been decline in abundance inferable from losses of breeding sites, and population sizes probably fluctuate to a great extent.  However, these cannot be determined with as much certainty as can the qualifications under Criterion B.

Criterion D: Meets the criterion for Threatened D2 because Area of Occupancy is less than 20 km² and number of locations <5.

Criterion E: Insufficient information to calculate.

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