Scientific Name: Ambystoma texanum
Other/Previous Names: Smallmouth Salamander
Taxonomy Group: Amphibians
Last COSEWIC Assessment: May 2014
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Small-mouthed Salamander
The Small-mouthed Salamander has a relatively small head and, as its name would suggest, it has a short, narrow snout. This salamander has small teeth arranged in at least two rows. The back is black or very dark brown and the belly is black with a few light spots. The flanks and the long tail are covered with light grey-blue spots that resemble lichen. The larvae have pigmented throats. This average-sized salamander can grow to a maximum length of 17.8 cm. Males are smaller than females, but their tails are longer.
Distribution and Population
The Small-mouthed Salamander occurs in the United States in the coastal plain extending from eastern Texas to western Alabama, in Louisiana and Mississippi, and in areas northward to the extreme southeast of Michigan, northern Ohio and Pelee Island in Ontario. This species’ area of occurrence in Canada is no more than 40 km2 (i.e., the total area of Pelee Island, the largest island in Lake Erie). Although considered abundant in 1991, the species was nonetheless designated as vulnerable by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) due to the extremely limited size of its Canadian range. In the spring of 2000, the Small-mouthed Salamander was noted in three existing breeding grounds on southern Pelee Island (Pond, Stone Road and Mosquito Point Woods) and in a remnant forest habitat, representing a total area of occupancy of no more than 5 km2. This constitutes a significant reduction of its range on the island. Two of the five breeding grounds that were still in existence in 1991—North End Woods and Girl Guide Pond on the northern and eastern shores of the island—seem to have disappeared. These formerly flooded woodlots where the highest frequencies of Small-mouthed Salamanders were once noted are now dry land. It is interesting to add that hybrids resulting from the mating of this species with the Blue-spotted Salamander can be found on Pelee Island (see the Biology section). Data on approximately 1200 larvae captured between 1983 and 1991 indicate that these hybrids represent 78% of the salamanders captured at known breeding grounds on Pelee Island. This data also revealed that the frequency of “pure” Small-mouthed Salamander and Blue-spotted Salamander specimens in relation to the frequency of various hybrid types varies within each population. As it is extremely difficult to differentiate the Small-mouthed Salamander from certain hybrids without genetic testing, the discovery of a large number of eggs, larvae, or even adults serves only to confirm breeding success and not population densities for this species. The breeding success of female hybrids is known to be dependant on their association with male Small-mouthed or Spotted Salamanders. The discovery of larvae and juveniles in populations that have been found to contain only Small-mouthed Salamanders proves the species’ persistence in the area. It is impossible to determine the density of “pure” populations or to assess trends due to the difficulties associated with the identification of Small-mouthed Salamanders in the field. There are currently no population estimates for the Small-mouthed Salamander on Pelee Island.
In Canada, the Small-mouthed Salamander can be found in several types of moist habitats, including tall-grass prairies, dense hardwood forests and agricultural lands that provide suitable breeding grounds such as ponds and other natural basins. The most important habitat requirements for this burrowing species include soft soil in which to dig burrows and temporary or permanent fishless water bodies for breeding. Outside the breeding season, adults spend most of their days hidden in burrows dug by themselves or by other species, underneath decomposing tree trunks, rocks or fallen leaves. The larvae are aquatic.
These salamanders mate and lay their eggs in marshes and ponds in early spring (late March or early April). Females generally lay 200 to 300 eggs, individually or in small piles, on the dead leaves and twigs that line the bottom of the breeding pond. The eggs hatch after 9 or 10 days and small larvae are born. Metamorphosis occurs three months later in June or July when the larvae turn into terrestrial adults. Small-mouthed Salamanders reach breeding age two years after this metamorphosis. These nocturnal salamanders do not migrate very far, as breeding ponds and areas inhabited by adults are close to one another. Larvae and adults feed on a variety of invertebrates, including insects. The life expectancy of adults in a natural environment is not known, but they can live at least 15 years in captivity. This species presents an interesting particularity: like other salamander species of the Ambystoma genus, this species includes hybrids resulting from interbreeding between the Small-mouthed Salamander and the Blue-spotted Salamander. In fact, several triploid and a few tetraploid individuals, each with one or two sets of chromosomes instead of two, have been identified on Pelee Island. It is now known that hybrid egg division and development are activated, without fertilization, by the spermatozoa of “pure” males.
Due to its extremely limited range in Canada, this species is particularly vulnerable to the degradation of the environment, drops in the water level and other factors that result in the destruction of its habitat. Various development activities have occurred in the northern and eastern parts of Pelee Island, and areas that were once home to this species appear to have disappeared. The felling of trees and the removal of decomposing stumps are detrimental to salamanders because forest cover slows the evaporation of breeding ponds and wetlands, and rotting trunks provide habitats for the invertebrates on which adult salamanders feed. A drop in the water level could also be detrimental to the Small-mouthed Salamander. For instance, the low water level in Mosquito Point Woods could pose a problem if the area were to dry out too quickly or if rainfall were insufficient to ensure the area remains flooded, particularly during the critical March to July period (breeding season and larvae metamorphosis period). Fortunately, the fact that breeding occurs at night and that salamanders remain underground during the tourist season minimizes the risk of capture for adult individuals. However, competition with the increasing number of hybrids can potentially become a limiting factor, although the continued presence of these hybrids depends in part on the presence of male Small-mouthed Salamanders.
Federal ProtectionThe Small-mouthed Salamander is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
Two of the five breeding ponds or grounds used by the Small-mouthed Salamander (Mosquito Point Woods and the Stone Road site) are found in the nature reserves on Pelee Island. The largest population of Small-mouthed Salamanders is found in the Mosquito Point Woods site in the Fish Point Provincial Nature Reserve, which is part of Ontario’s provincial park system. The Stone Road site is on land belonging to the Federation of Ontario Naturalists and the Essex Region Conservation Authority.
Provincial and Territorial Protection
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
12 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (2 record(s) found.)
- Response Statements (2 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (2 record(s) found.)
- Consultation Documents (2 record(s) found.)
- Recovery Document Posting Plans (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2004 (2004)2004 Annual Report to the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
Recovery Document Posting Plans
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