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Canadian Herpetological Society Société d'Herpétologie du Canada |
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Jefferson Salamander
Ambystoma jeffersonianum
Family: Ambystomatidae
COSEWIC status:- Endangered
- Endangered
- Least Concern
Description
Jefferson Salamanders are heavy-bodied and can reach 20 cm in total length. The dorsal colour is grey to brown with varying amounts of blue flecks and spots along the sides, although some individuals show little to no flecking. The belly is dark grey with a lighter grey colour around the vent. The limbs and snout are relatively long. Terrestrial juveniles have light grey to brown dorsal colouring and smaller, more diffuse blue to yellow spots. Aquatic larvae have feathery gills behind the head, legs (both front and back) and a tail fin and are generally a mottled grey-brown with yellow mottling.
Similar Species
Small-mouthed salamanders have a short snout, small toes and grey mottling and in Canada they are only found on Pelee Island. Blue-spotted Salamanders are dark grey to black with varying amounts of blue flecks and spots, and they have a shorter snout and shorter toes. Ambystoma unisexuals can overlap in body form and colouration making identification almost impossible without genetic tests. Aquatic larvae of all Ambystomatidae salamanders are difficult to distinguish from one another.
Distribution
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In Canada, Jefferson Salamanders are restricted to southwestern Ontario. In the United States, they range from eastern Illinois and south central Kentucky north-east to northern Virginia and southwestern New England.
Habitat
Jefferson Salamanders are usually found in deciduous and mixed forests, typically within close proximity to breeding habitats. Leaf litter and cover objects, such as logs and rocks, are important microhabitats where the salamanders forage and seek shelter. Individuals are sometimes found beneath wood piles and other debris in back yards. This species breeds in vernal pools (temporary woodland ponds) or fish-free permanent wetlands. Jefferson Salamanders overwinter underground below the frost line in mammal burrows, root cavities and other underground crevices.
Biology
Jefferson Salamanders migrate to breeding wetlands on rainy nights in early spring, often moving over snow banks and the icy edges of thawing ponds. Adults can migrate several hundred metres between overwintering and breeding sites. Each female will lay up to 300 eggs as small gelatinous masses of approximately 30 eggs each, which she attaches submerged sticks or other vegetation. The eggs hatch into aquatic larvae after about one month, and the larvae transform into terrestrial juveniles by the end of summer. Individuals reach sexual maturity in two or three years and may only breed every few years. There is little information on the longevity of this species, but individuals may live more than 20 years based on studies on other Ambystomatid salamanders. After the breeding season, adults spend most of their time in underground burrows and cavities, making them difficult to find them during the summer and fall. Adults and juveniles eat insects, spiders, worms and other terrestrial invertebrates, while larvae prey on immature aquatic insects and microcrustaceans.
Threats
The extensive conversion of natural habitat to agricultural and urban land uses has destroyed and fragmented much of this species’ habitat throughout its Canadian range, and habitat loss continues to cause population decline and local extirpation. Road mortality can be a significant threat to this species when roads bisect spring migration routes. 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.