|
Canadian Herpetological Society Société d'Herpétologie du Canada |
|---|
Western Long-toed Salamander
Ambystoma macrodactylum macrodactylum
Family: Ambystomatidae
The Western Long-toed Salamander is a subspecies of the Long-toed Salamander (Ambystoma macrodactylum).
COSEWIC status:- Not at Risk
- No Status
- Least Concern
Description
The Western Long-toed Salamander is dark grey with an irregular-edged bright green to yellow dorsal stripe that that is reduced to small flecks on the head. There is often white speckling on the sides and the belly is grey or black. This salamander is named after the very long toe on the hind foot (second from the outside). Individuals have 12–13 costal groves and can grow up to 17 cm in total length. Aquatic larvae have feathery gills behind the head, legs (both front and back) and a tail fin and are generally brown or green with dark brown and black mottling.
Similar Species
This species may be confused with the other subspecies of Long-toed Salamander, the Western Red-backed Salamander and the Couer d'Alene Salamander. The dorsal stripe on the Northern Long-toed Salamander continues onto the head, while the dorsal stripe on the Eastern Long-toed Salamander becomes large spots and blotches on head. The dorsal stripe also tends to be more greenish on the western subspecies and is typically yellow to tan on the other subspecies. It is easiest to distinguish these subspecies based on their distribution. Both the Western Red-backed Salamander and the Couer d'Alène Salamander lack long toes on the hind feet and are slenderer than the Long-toed Salamander. Furthermore, the Western Red-backed Salamander has a smooth-edged red dorsal stripe rather than an irregular-edged yellow, orange or green dorsal stripe.
Distribution
Click for larger image
In Canada, the Western Long-toed Salamander is restricted to southwestern British Columbia and only occurs on Vancouver Island and in the lower Fraser River valley. In the United States, this subspecies is restricted to western Washington and northwestern Oregon.
Habitat
Long-toed Salamanders breed in permanent or semi-permanent lakes, ponds or wetlands that are fish-free. They inhabit a variety of terrestrial habitats within close proximity (usually within 100 m) of these breeding sites, including forest, meadows and grassland. Like many salamanders, areas with moist microhabitats are preferred. Logs, rocks and other cover objects, as well as underground burrows and crevices, are important microhabitats where the salamanders forage and seek shelter. Individuals overwinter underground below the frost line in rodent burrows, root hollows or other underground cavities.
Biology
Long-toed Salamanders migrate to breeding sites on rainy nights in early spring, often before the ice has fully receded. Each female will attach up to 400 eggs singly or in small clumps of up to 30 eggs to submerged sticks or vegetation in shallow water. The eggs hatch into aquatic larvae after two to five weeks. At lower elevations the larvae transform into terrestrial juveniles by the end of summer, but at higher elevations where water temperatures are cooler the larvae may overwinter and transform the following spring. In Canada, Long-toed Salamanders reach sexual maturity in two to three years, and individuals may live up to 10 years. 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, microcrustaceans, tadpoles or other salamander larvae. Long-toed Salamanders secret a sticky toxin from pores in their skin that provides defense against predators.
Threats
Habitat loss and fragmentation, primarily as a result of urban development and logging, is a threat to this species in some parts of its range. Road mortality can be a significant threat to Ambystoma salamanders 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. The introduction of predatory sport fish into breeding habitats can quickly decimate local populations. Climate change and introduced pathogens pose potentially serious threats to Canadian salamanders.