Small-mouthed salamander (Ambystoma texanum) COSEWIC assessment and status report: chapter 2

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Executive Summary

In this update of the 1991 status report for the Small-mouthed Salamander, we bring together all available data that relate to the distribution of Ambystoma texanum on Pelee Island: the only Canadian locality for this species. We include locality information for Ambystoma texanum, A. laterale and diploid, triploid and tetraploid genomic hybrids that also exist on the island because: (1) the identification of A. texanum, and distinguishing that species from the genomic hybrids is confusing; and (2) both A. texanum and A. laterale males are used as sperm donors for the persistence of genomic hybrid combinations. Although this update only considers the status of “pure” diploid A. texanum, the presence of rare A. texanum males can be estimated through an examination of the more common genomic hybrids.

Preliminary DNA sequence information suggests that Ambystoma texanum on Pelee Island are the result of more than one historic invasion from the United States mainland. Known breeding sites from the 1980s were re-visited in the spring of 2000 to estimate trends and to establish a current list of important breeding sites. Two of the five breeding sites from 1991, on the north and east side of the Island, appear to have been eliminated. Ambystoma texanum appears now to be restricted to two areas (breeding sites) in the southern part of Pelee Island. Both areas are within protected zones. The presence of adults and larvae at both sites provides evidence that recruitment is occurring.

Diploid and polyploid hybrid combinations that incorporate A. texanum nuclear genomes are more common than the pure species and it is estimated that the breeding population would include fewer than 1000 pure, diploid A. texanumindividuals on the Island. Ambystoma texanum is listed as threatened by the Ontario Ministry of Natural Resources (OMNR). Presently, A. texanum exists in an area of approximately 1000 ha across the southern quarter of Pelee Island. This is a considerable reduction in the range of this salamander on the island that coincides with the reduction in previously known breeding sites.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed  under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species and include the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal organizations (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biosystematic Partnership, chaired by the Canadian Museum of Nature), three nonjurisdictional members and the co-chairs of the species specialist and the Aboriginal Traditional Knowledge subcommittees. The committee meets to consider status reports on candidate species.

Definitions (after May 2004)

Species

Any indigenous species, subspecies, variety, or geographically defined population of wild fauna and flora.

Extinct (X)

A species that no longer exists.

Extirpated (XT)

A species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A species facing imminent extirpation or extinction.

Threatened (T)

A species likely to become endangered if limiting factors are not reversed.

Special Concern (SC) ^Footnote1

A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

Not at Risk (NAR) ^Footnote2

A species that has been evaluated and found to be not at risk.

Data Deficient (DD) ^Footnote3

A species for which there is insufficient scientific information to support status designation.

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.