The Four-toed Salamander is slender-bodied and can reach 10 cm in total length. Individuals are brown or grey with varying amounts of orange, especially on the tail and the head. There is often white flecking on the sides and dark mottling or spots on the back. The belly is white with pronounced black spots or mottling. Four-toed Salamanders are the only terrestrial salamanders in eastern Canada with four toes rather than five on their hind feet. Individuals have 13–14 costal groves and a constriction at the base of the tail.
The Four-toed Salamander can be confused with several other species of Plethodontid salamanders; however, it is the only terrestrial species in eastern Canada with four toes on its hind feet (rather than five). The Eastern Red-backed Salamander lacks a constriction at the base of the tail and the pronounced black spots on the belly. The dusky salamanders have a diagonal line running from the jaw to the eye and a laterally compress tail. The Northern Two-Lined Salamander has two dark lines running down the back and a laterally compressed tail.
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In Canada, the Four-toed Salamander occurs in the Great Lakes region in Ontario east through southern Quebec and in isolated areas of New Brunswick and Nova Scotia. This species occurs throughout the eastern United States from Maine south to Florida and as far west as southern Oklahoma, with much of the southern parts of the range being disjunct.
The Four-toed Salamander inhabits forests and breeds in sphagnum bogs, swamps, vernal pools and other fish-free wetlands. The eggs are typically deposited above the water in sphagnum moss within or around the edges of the wetlands. Individuals overwinter below the frost line in mammal burrows, root hollows or other underground cavities.
Plethodontid salamanders, including the Four-toed Salamander, are also known as lungless salamanders because the adults do not have lungs; instead, they absorb oxygen directly through their skin. They must remain moist at all times so that oxygen and carbon dioxide can diffuse through the skin. Four-toed salamanders usually mate in the fall and females lay 4–80 eggs the following spring. The females remain with the eggs for extended periods of time, sometimes until they hatch four to eight weeks later. Sometimes many females nest in the same location, but only one or two females will stay with the communal nests. The larvae are aquatic for about six weeks before transforming into terrestrial juveniles. Four-toed Salamanders reach maturity two years after metamorphosis and individuals can live up to 9 years. Four-toed Salamanders are most active during wet weather and forage on the forest floor insects, spiders, mites and other arthropods. When threatened, individuals may autotomize (drop) their tail, which creates a diversion while the salamander escapes. Although the tail will grow back over time, the individual will have lost much of the fat reserves on which it relies to survive the winter.
The extensive conversion of natural habitat to agricultural and urban land uses has destroyed and fragmented much of this species’ habitat throughout the southern portion of its range in Canada. Pollution, such as herbicides, agricultural effluent and road salt can be detrimental to salamanders since toxins are easily absorbed though their skin. Climate change and introduced pathogens pose potentially serious future threats to Canadian salamanders.