Northwestern Salamander

Contents:
 
Links:
Taxon, Status, and Ranks Habitat Photos
General Description State Status Comments
Identification Tips Inventory & Research Needs Key Features
Phenology Threats & Mgmt Concerns
Range References Distribution Map

Taxon, Status, and Rank

Species Ambystoma gracile     (Baird)
Family Ambystomatidae
(Mole Salamanders)
Status None
State Rank S5
Global Rank G5

General Description

A large, stocky, brown salamander with a rounded snout, prominent parotoid glands (poison glands) behind the eyes, distinct costal grooves and a laterally compressed tail with a glandular ridge on the dorsal surface. Adults are 80-90 mm snout-vent length, 140-220 mm total length. During the breeding season, males have conspicuously swollen vent lobes and females have a rounded protuberance around the vent.

The egg masses are firm, globular and attached to sturdy plant stalks and twigs. The egg masses may be round or elongate and are about the size of an orange measuring 8-15 cm in diameter. Ova are light brown at one pole and cream colored at the other. When first laid the gel around the eggs has a white tint. Fully expanded egg masses exposed to sunlight develop a distinct greenish tinge from symbiotic algae that grow in the inner jelly layer.

Larvae are pond-type with large gills and a high tail fin. Hatchlings have translucent skin with dark spots and yellow bellies. Rod-like extensions on the head, called balancers, are present. Small larvae are typically olive or brown in color, usually with dark spots or mottling. The gill filaments are closely packed on the gill stalks and are similar in length. Hind limbs develop after the larvae grow to 25 mm total length. Large larvae (>50 mm SVL), are olive to brown in coloration often with dark spots or mottling. They develop huge gills with thick gill stalks, robust legs and glandular patches on the head and tail. The glandular patches are less conspicuous than on transformed juvenile and adults. The belly coloration tends to be cream, gray or brown depending on the size and stage. Large larvae and gilled adults (neotenes) can grow larger than 77 mm total length. The number of gill rakers on the anterior arch of the 3rd gill arch number less than 13 (range 7-10). See Photos Page.

Identification Tips

Transformed Northwestern Salamanders are easily distinguished from all other Washington salamanders by the conspicuous parotoid glands on the head and the glandular ridge on the tail.

Eggs: In Washington, only Northwestern Salamanders have large globular egg masses that are firm to the touch.

Larvae: Newt larvae differ in having eyes on the margin of the head, a snout that narrows in front of the eyes, a faint horizontal stripe from the snout through the eye, and one or two distinct rows of white spots down the back and sides.

No obvious external characteristics distinguish small Long-toed Salamander larvae (less 25 mm TL) from Northwestern Salamander larvae. With experience, one can recognize subtle differences in the gills, the way the larvae hold their gills, head size, head shape and coloration. Corkran and Thoms (1996) discuss some of these differences in their field guide.

In general, Long-toed Salamander larvae have gill filaments that are “ragged” and uneven in length. The top gill filament is usually longer than the rest of the gill filaments on the stalk. The skin coloration tends to remain somewhat translucent and is less likely to have distinct spotting. Hind leg development starts before larvae reach 25 mm TL and larvae remain relatively small (rarely exceed 80 mm total length) and never develop huge gills or robust legs.

The range of the Northwestern Salamander overlaps with the Tiger Salamander only in southwestern Klickitat County where one Tiger Salamander specimen was collected in the 1930s. The location is isolated from the rest of the Tiger Salamander range and the exact collection site is unknown. Larvae of these two species are similar in general appearance but large Northwestern Salamanders usually have glandular patches on the head and tail. Gill counts can be used to confirm species of larvae that lack glandular patches. Tiger Salamanders have more than 13 gill rakers on the anterior surface of the 3rd gill arch whereas Northwestern Salamanders have fewer. See Key Features Page.

Phenology

Metamorphosed forms spend most of their lives in the subterranean environment and are rarely seen except for spring migrations to breeding ponds. Surface activity is nocturnal. They shelter under woody debris, ground litter, and accumulated duff below sword ferns. Breeding starts in late January through March at lower elevations (less 1000 ft), later at higher elevations. The embryos take one to two months to develop. The empty gelatinous egg masses persist for weeks to months after hatching is complete. Larvae may transform in their second year around 50 mm SVL (75-90 mm TL) or may remain permanently aquatic. Observations at some sites suggest that larva may transform in the first year under certain conditions (pond drying). Ponds often contain many different size classes of larvae, including gilled adults (neotenes). Populations are highly polymorphic, consisting of populations that always transform, populations that never transform and populations that metamorphose depending on environmental conditions Gilled adults tend to dominate high-elevation populations.

Range

In Washington, Northwestern Salamanders occur primarily west of the Cascade Crest in the Pacific Coast, Puget Trough and West Cascades Ecoregions. They also occur east of the Cascade Crest in some areas of the East Cascades Ecoregion. See Distribution Map.

For information on the complete range of this species, see NatureServe Explorer.

Habitat and Habits

Mesic forests are the main terrestrial habitat occupied by this species. One Washington study found them to be less abundant in young forest when compared to older forests, but other studies have found little correlation of abundance with stand age. Northwestern Salamanders use permanent water bodies for breeding. Breeding habitats include ponds, wetlands, lakes, road ditches and slow moving creeks.

Larvae and gilled adults can persist in the presence of introduced trout but may be forced to use sub-optimal habitats and to forage at night. This may result in reduced size and recruitment. Anecdotal observations suggest that large populations of introduced warm-water fish, such as Largemouth Bass, may deter salamander breeding.

State Status Comments

This species is common and occurs throughout western Washington.

Inventory and Research Needs

Observations that occur in areas that are not indicated on the distribution map can be submitted to the Washington Department of Fish and Wildife herp database by contacting Lori Salzer by E-mail salzeljs@dfw.wa.gov.

Experimental research that addresses the impact of introduced warm-water fish on Northwestern Salamander populations is of interest.

Current or Recent Research in Washington

Angela Stringer conducted a telemetry study of Northwestern Salamanders in Pierce County between 1995 and 1998 while a student at University of Washington.

Threats and Management Concerns

Activities that alter breeding habitat or access to breeding habitat, such as clear-cutting, wetland drainage, beaver control, land conversion and introduced fish, are most likely detrimental to this species.

References

Aubry (1997, 2000), Aubry and Hall (1991), Aubry et al. (1997), Bury and Corn (1988), Corkran and Thoms (1996), Corn and Bury (1991), Eagleson (1976), Eagleson and McKeown 1980, Grialou (2000), Hallock and Leonard 1996, Larson and Hoffman (2002), Litch 1975, Nussbaum et al. (1983), Petranka (1998), Ruggiero et al. (1991), Snyder (1956,1963), Sprules (1974), Stebbins (1951, 2003), Tayler et al. (1998).

Personal communications: Angela Stringer




Hallock, L.A. and McAllister, K.R. 2005. Northwestern Salamander. Washington Herp Atlas. http://www1.dnr.wa.gov/nhp/refdesk/herp/

Last updated: December 2005


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