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Small-mouthed Salamander

Ambystoma texanum

Family: Ambystomatidae

COSEWIC status:
  • Endangered
SARA status:
  • Endangered
IUCN status:
  • Least Concern

Description

Small-mouthed Salamanders are heavy-bodied and can reach 18 cm in total length. Adults are dark brown to greyish-black with varying amounts of grey flecks or mottling, which are concentrated along the sides. The belly ranges from dark grey to black. Terrestrial juveniles may lack the grey flecking for the first few weeks. Individuals have 14–15 costal groves and a noticeably small head and snout. Aquatic larvae have feathery gills behind the head, legs (both front and back) and a tail fin and are brown to olive in colour with three to six paired light yellowish blotches on the back.

Similar Species

Blue-spotted Salamanders also occur on Pelee Island. They have larger heads and blue mottling or flecking rather than gray. Ambystoma unisexuals can overlap in body form and colouration making identification almost impossible without genetic tests. Aquatic larvae of Ambystomatidae salamanders are difficult to distinguish from one another.

Distribution

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The Small-mouthed Salamander only occurs on Pelee Island in Canada. In the United States, the species ranges from Ohio west to eastern Kansas and south to Texas, Louisiana, Mississippi and Alabama.

Habitat

Small-mouthed 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. This species breeds in shallow ephemeral woodland ponds or fish-free permanent wetlands. Small-mouthed Salamanders overwinter underground below the frost line in mammal burrows, root cavities and other underground crevices.

Biology

Small-mouthed 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 can lay up to 500 eggs, which she attaches singly or in small gelatinous masses to submerged sticks or other vegetation. The eggs hatch into aquatic larvae after about two to four weeks, and the larvae transform into terrestrial juveniles by the end of summer. Individuals reach sexual maturity in two 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 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 conversion of wetlands and forests to agricultural land uses has destroyed and fragmented much of this species’ habitat on Pelee Island, and populations are now restricted to only a few breeding ponds. Ongoing drainage activities and the potential for further habitat loss continue to threaten the persistence of this species 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.

Additional Information About This Species In Canada