The Streetsville area of Mississauga is home to one of the few remaining populations of the threatened Jefferson salamander. As the first identified Canadian population, the UTM site was stumbled upon in 1976 by an Erindale graduate student researching his thesis. Recently, urban expansion and development in southwestern Ontario destroys and degrades the habitat of the Jefferson salamander, threatening its existence.
Since their discovery, the Jefferson salamanders act as indicator species, signalling the health of the entire ecosystem.
“Since the adult salamanders live largely underground in natural cavities in undisturbed forest floors, their presence is a guaranteed indicator that the land around them has been relatively undisturbed for quite awhile,” writes associate professor Nicholas Collins of the biology department at UTM in an email correspondence.
Data suggests the existence of 13 sites in three main areas of southern Ontario. At the UTM site, Environment Canada and Credit Valley Conservation will fund research by UTM faculty and students to understand the biology of the secretive salamanders. Their research aims to determine whether the current population is healthy and if the breeding pond is in danger of filling in or otherwise becoming unsuitable for the population.
“We’re also measuring how often the area inhabited by the salamanders is disturbed by people and pets, and doing some inventories of microhabitats known to be used by the salamanders,” says Collins.
With a lifespan of up to 30 years, female and male salamanders breed in late March. Salamanders spend the rest of the summer and fall in the forested areas surrounding the breeding pond and winter in underground sites. Survival rates for both larvae and young Jefferson salamanders are unknown.
“The populations are, as far as I know, relatively local and small, so that if they go extinct, the site is unlikely to be re-colonized. Bottom line is, if they are there now, that’s good evidence of a relatively continuous long-term stable condition in the immediate area,” says Collins.
Small populations are susceptible to local extinction due to chance events such as floods, fire, or other catastrophes. At the UTM site, current population size and trends are unknown.
The presence of triploid individuals in the population further complicates our understanding of salamander populations. Jefferson salamanders interbreed with the closely related Blue-Spotted salamanders to produce hybrid offspring. The offspring contain a triploid chromosome number, two copies from the Jefferson salamander and one copy from the Blue-spotted salamander. Hybrids are difficult to distinguish from the parent species by sight alone. That means identification of the Jefferson salamander often requires genetic analysis.
In order to reverse the habitation threats to the salamander population, Dr. Collins suggests that, “minimal disruption or change and vigilance to recognize subtle negative influences is needed.”
The Jefferson salamander is listed in the Ontario Fish and Wildlife Conservation Act, which protects the Jefferson salamander against killing, harassment or capture.
