Jefferson salamander © Scott Gillingwater
Characteristics
The Jefferson salamander is black or grey-brown with bluish white spots. Individuals up to 20 centimetres in length have been recorded. The spotted salamander (Ambystoma maculatum) and the mudpuppy are the only two Ontario salamander species known to grow larger than the Jefferson salamander.
The Jefferson salamander (Ambystoma jeffersonianum) and the blue-spotted salamander (Ambystoma laterale), by virtue of a complicated hybridization scheme, present one of the great mysteries of amphibian biology.
Jefferson salamander © Scott Gillingwater
Similar Species
Jefferson and blue-spotted salamanders cannot be distinguished reliably without genetic testing. Where their ranges overlap, hybridization between the two species complicates identification even further.
Small-mouthed salamanders appear similar to salamanders in the Jefferson complex and hybridize with them where their ranges overlap. The eastern red-backed salamander in the leadback colour phase can be distinguished from the Jefferson complex salamanders by its much thinner body and limbs, and lack of blue spots.
Jefferson salamander © Scott Gillingwater
Habitat
Jefferson salamanders are found in a wide variety of woodland habitats (deciduous, coniferous or mixed forests), as well as swamps. Typically, these salamanders spend their lives on the forest floor, often living underground in burrows. They breed in permanent swamps or temporary ponds, marshes or even roadside ditches, and overwinter underground in the forest.
View an interactive map of the known ranges of Jefferson salamanders in Ontario.
Biology
Jefferson salamanders are nocturnal (most active at night) and are especially active on warm rainy nights. Breeding occurs in late March. Females can lay up to 300 eggs in small, gelatinous masses of about 30 eggs either singly or in loose clumps, that are attached to underwater vegetation. The eggs hatch three to four weeks later, and the larvae transform into adult salamanders in late summer. Outside of the breeding season, adults are terrestrial carnivores, eating a large variety of insects and other invertebrates, including spiders and worms.
Other names: Ambystoma tremblayi, Salamandra jeffersoniana, Ambystoma platineum
Juvenile Jefferson salamander © Scott Gillingwater
Hybrid
The Jefferson salamander and the blue-spotted salamander are part of one of the most bizarre and complex mysteries of amphibian biology. These two species are associated with hybrids, usually female, that have three, four or even five complete sets of chromosomes (such individuals are referred to, respectively, as triploid, tetraploid or pentaploid) in their DNA rather than the usual two sets (diploid). Under certain circumstances, when hybrid females breed with male blue-spotted or Jefferson salamanders, sperm stimulates egg development but is not incorporated into the genetic material of the egg. In such cases, the offspring are genetically identical to the mother. Sometimes one or both chromosomes of the sperm are incorporated into the egg, producing offspring with three or four sets of chromosomes (triploids or tetraploids, respectively). Further complicating the issue, hybrids that have more than two sets of chromosomes can mate with either species and produce offspring that have four or more sets of chromosomes. No matter what their ploidy level (number of sets of chromosomes), these salamanders appear nearly identical. Biologists are still trying to fully understand this complicated genetic system.
Jefferson salamander © Ryan Wolfe
Threats and Trends
Extensive agricultural development and urbanization in south-central Ontario have severely reduced and fragmented the wetlands and forest habitat available to this species. Jefferson salamanders are also killed on roads every spring during their migration to breeding ponds.
Because its range coincides with one of the most developed areas of Canada, the Jefferson salamander will probably continue to decline, and its tendency to hybridize will continue to complicate and frustrate conservation efforts.
Jefferson salamander © Scott Gillingwater
Current Status and Protection
The Jefferson salamander is currently listed as Endangered under both the Ontario Endangered Species Act, 2007 and the federal Species at Risk Act. The species has also been designated as a Specially Protected Amphibian under the Ontario Fish and Wildlife Conservation Act. These acts offer some protection to individuals and their habitat.
The International Union for Conservation of Nature lists the global status of the Jefferson salamander as Least Concern. The species’ status was last confirmed in February 2021.
Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.
Jefferson salamander © Scott Gillingwater
What You Can Do
- Report a sighting
- Get involved in reptile and amphibian conservation on your property, on the road and in your community
- Donate to support reptile and amphibian conservation
- Watch for reptiles and amphibians on the road
- Don’t release pet reptiles and amphibians into the wild
- Read more about the Jefferson salamander in the Ontario Reptile and Amphibians Atlas publication.
Jefferson salamander © Ryan Wolfe