Ministry of Environment
|Common Name:||Northwestern Salamander|
|Scientific Name:||Ambystoma gracile|
|Status (COSEWIC):||Not at Risk|
Northwestern Salamanders are relatively large, reaching a maximum total length of 24 centimetres. The body is usually uniformly dark brown, but sometimes individuals are grey or black, and they may have light flecks on their backs. Adult and juvenile Northwestern Salamanders have relatively large, dark, protruding eyes. In addition, adults have broad heads with large parotoid glands visible as swellings behind the eyes. These glands, as well as the granular glands along the sides of the tail, can exude a mild white poison if the animal is threatened. Adults have a broad, vertically flattened tail and large hind feet used for swimming and burrowing. This salamander also has 10 to 12 prominent costal grooves (furrows that resemble ribs along the side of the body) between the front and rear legs.
Northwestern Salamander larvae are aquatic, with large, feathery gills. They generally have a dark body with a light grey or translucent tail. The dark body is olive to brown with light-coloured mottling, while the tail area has dark spots. The underside of the body is usually white, cream or gold in colour.
This species can also exhibit neoteny, where some individuals reach sexual maturity while retaining larval characteristics, such as gills. These individuals remain aquatic their whole life, inhabiting permanent ponds and lakes that do not freeze solid in winter.
Northwestern Salamanders are dependent on both forests and permanent water bodies for their survival. Although they can be found in a wide variety of habitats, they are most common in mature, cool, moist forests, where they spend the majority of their time underground (for example, in burrows dug by mammals), or under logs, rocks and debris. These salamanders, especially dispersing juveniles, may travel extensively in terrestrial environments.
Northwestern Salamanders gather at wetlands, ponds, lake edges, ditches, and slow moving streams during the spring breeding season. The courtship behaviour of these salamanders involves the male rubbing his chin along the female’s head. He then deposits a sperm sac (spermatophore) on the bottom of the pond or stream that the female picks up with her cloaca. Once fertilized, the female attaches her grapefruit-sized mass of up to 270 eggs to vegetation or sticks about 5 to 20 cm below the surface of the water. The eggs take anywhere from 2 to 8 weeks to hatch, depending on water temperature. Larvae transform to a terrestrial form in one to two years. Northwestern salamanders take at least one year after metamorphosis to reach sexual maturity, and can live at least 5 years.
Both larval and adult Northwestern Salamanders are carnivores. Juveniles and adults eat a wide variety of terrestrial invertebrates, including insects, spiders, worms, and slugs. Larvae feed on invertebrates and zooplankton, tiny aquatic animals.
The poison produced by Northwestern Salamanders affords them some protection from predators. When threatened, Northwestern Salamanders assume a head-butting posture with eyes closed and tail raised. In defending itself, the salamander lashes its tail at the attacker in an attempt to smear poison on it. However, larval and adult salamanders are still vulnerable to predation by some fish, mammals, birds, and reptiles
Northwestern Salamanders are found along the coast range from the southern tip of the Alaskan Panhandle down to northern California, from sea level to 3000 metres. This range in latitude and elevation partly explains the variations observed in the timing of the breeding season across the range, which is from February through August. The relatively large egg masses from these salamanders can be observed through spring and early summer, depending on elevation and water temperature. Aquatic forms of Northwestern Salamanders (larvae and neotenes) can be found year round in permanent water bodies. Outside of the breeding season terrestrial adults and juveniles are rarely seen, except perhaps during fall rains. For the most part, Northwestern Salamanders are inactive in winter, seeking refuge under ground away from freezing temperatures.
Although very elusive and hard to find, the Northwestern Salamander appears to be doing well. It can live in a wide variety of forested habitats and can avoid many predators. This species is on the provincial Yellow List of species managed at the ecosystem level. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has designated this species as Not At Risk.
By monitoring this species through Frogwatch and other programs we hope to learn more about these salamanders and their habitat requirements. In this way, we can better maintain the species’ population, as well as those of other amphibians. The Northwestern Salamander is protected under the British Columbia Wildlife Act.
You can help by learning more about these interesting animals, and by teaching others to appreciate them and other amphibians. As people develop greater awareness of salamanders and their needs, they will be more concerned about protecting them. Monitoring local populations and contributing data to B.C. Frogwatch is also a great way to help with conservation.
- The Northwestern Salamander is one of the few native amphibians able to survive in areas where predatory fish and bullfrog populations have become established. This is likely due to the poisons they secrete.
- The poison secreted from their head, body, and tail is strong enough to kill some small predators such as snakes and shrews, but can only cause mild skin irritation in people.
- The egg masses of this salamander accumulate a symbiotic green algae within the jelly layer of the eggs. This gives the eggs a green, slimy look, and allows people to estimate how long the eggs have been there. It also sets these eggs apart from the eggs of other species.
Photo © Wally Edwards. No reproduction or distribution without permission.