The blue-spotted salamander and the Jefferson salamander (Ambystoma jeffersonianum), by virtue of a complicated hybridization scheme, present one of the great mysteries of amphibian biology.
The blue-spotted salamander is black or grey-brown with bluish white spots. Individuals up to 16 centimetres in length have been recorded.
Blue-spotted and Jefferson 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 grey colour phase can be distinguished from the Jefferson complex salamanders by its much thinner body and limbs, and lack of blue spots.
Blue-spotted 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 blue-spotted salamanders in Ontario.
Blue-spotted salamanders are nocturnal (most active at night) and are especially active on warm rainy nights. Breeding occurs in the early spring in woodland ponds or swamps. Females can lay up to 200 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 by midsummer. Outside of the breeding season, adults are terrestrial carnivores, eating a large variety of insects and other invertebrates, including spiders and worms.
The blue-spotted salamander and the Jefferson 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.
Other names: Ambystoma tremblayi, Ambystoma nothagenes
Threats and Trends
The loss of wetlands (i.e., breeding habitat) threatens all salamanders. Forests (i.e., habitat for adult salamanders) are lost to logging, agriculture, and industrial and urban development. Acid rain has been proposed as a possible threat as well. Many blue-spotted salamanders are killed on roads every spring during their migration to breeding ponds. Reports of road-killed salamanders can be submitted to the Ontario Reptile and Amphibian Atlas and will help researchers identify these critical migration routes. Despite these threats, this species appears to be present in most of its historical range and is not considered to be at risk.
Current Status and Protection
Neither the Committee on the Status of Species at Risk in Ontario nor the Committee on the Status of Endangered Wildlife in Canada has assessed the status of the blue-spotted salamander. The species has been designated as a Specially Protected Amphibian under the Ontario Fish and Wildlife Conservation Act, which offers protection to individuals but not their habitat. The International Union for Conservation of Nature lists the global status of the blue-spotted salamander as Least Concern. The species’ status was confirmed in January 2010.
Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.