The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Ambystoma gracile
Ambystoma gracile
(Northwestern Salamander)
Native Transplant
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Ambystoma gracile (Baird, 1859)

Common name: Northwestern Salamander

Taxonomy: available through www.itis.govITIS logo

Identification: Ambystoma gracile are a large, heavy-bodied salamander with brown or gray to the nearly black coloration of their smooth skin. The salamander’s head is short, round and broad with small bulging eyes. Ambystoma gracile has two large swellings (parotid glands) on the back of their head behind the eyes (Stebbins and McGinnis 2012, California Herps 2019). Northern populations may have cream or yellow flecks on their back (California Herps 2019).

Efts (larval salamanders) have long feathery gills and are brown or olive green in color, with yellow, green, or black mottling along their dorsal-finned tail (Stebbins and McGinnis 2012, California Herps 2019). In some cases, Ambystoma gracile do not undergo metamorphosis from the aquatic larval stage to a terrestrial adult form. Instead, they remain in the water, reach adult size (65 to 105 mm snout to vent) and breed, but retain their gills and finned tails (California Herps 2019). This retention of juvenile features in an adult is called either paedomorphosis or neotenic (Stebbins and McGinnis 2012, California Herps 2019).

Size: Adults are 65 - 260 mm total length (Stebbins and McGinnis 2012, California Herps 2019)

Native Range: The native range stretches from south of the mouth of the Gualala River, CA north along the Pacific coast to extreme southeast Alaska (Stebbins and McGinnis 2012).

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences: No known established populations outside of Ambystoma gracile's native range. 

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Ambystoma gracile are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CA200020143San Diego; Santa Barbara Coastal; Upper Dry
FL201420141Florida Southeast Coast

Table last updated 3/8/2021

† Populations may not be currently present.

Ecology: Ambystoma gracile inhabit grassland, woodland and forest sites spending much of their adult life under rotten logs or underground, often utilizing the tunnels of burrowing mammals such as moles and ground squirrels (Stebbins and McGinnis 2012, California Herps 2019). Adult salamanders eat small terrestrial invertebrates (insects, worms, arachnids) and neotenic adults and efts (larvae) consume aquatic invertebrates including snails, worms, fairy shrimp along with tadpoles (California Herps 2019).

Ambystoma gracile breed in permanent or semi-permanent ponds, wetlands, or slow-flowing streams (California Herps 2019). The salamanders reach sexual maturity at 2-3 years of age and will breed at lower elevations between January and April and at higher elevations in the Cascade Mountains from June to August. Females will lay 30-270 eggs in large globular masses (size of a small grapefruit) and attached to underwater structures or plants (Stebbins and McGinnis 2012, California Herps 2019). Eggs hatch in 2-9 weeks based on water temperature (Stebbins and McGinnis 2012), and efts usually overwinter and metamorphose in 12-14 months at 65-85 mm in length (Stebbins and McGinnis 2012, California Herps 2019).

Adults and eft Ambystoma gracile are mildly poisonous and will excrete a sticky white poison from their parotoid glands on to its head, back, and tail. This is a unique feature to the species as no other mole salamander (ambystomid) has this gland developed to this extent (Stebbins and McGinnis 2012). When molested, the adult salamanders may emit a ticking sound and assume a defensive posture. Ambystoma gracile are known to survive in lakes and streams with populations of introduced fishes and bullfrogs (Lithobates catesbeianus), most likely due to their poison (California Herps 2019).

Means of Introduction: Hitch hiker on plants including the Noble Fir (Abies procera) Christmas trees originating from Oregon (Rochford et al. 2015).

Status: All known nonindigenous introductions have failed.

Impact of Introduction: As of yet, this species has not been adequately studied or evaluated to determine what ecological consequences, if any, have resulted from its introduction into the USA or elsewhere. To better understand and adequately assess the possible types and magnitude of any suspected ecological and economic impacts would most likely require further field and laboratory research, along with a review of any possible new literature on the subject.

The poison excreted by Ambystoma gracile can cause skin irritation in some people (California Herps 2019) and poison predators.

References: (click for full references)

California Herps. 2019. Northwestern Salamander - Ambystoma gracile. http://www.californiaherps.com/. Accessed on 06/03/2019.

Rochford, M.R., J.M. Lemm, K.L. Krysko, L.A. Somma, R.W. Hansen, and F.J. Mazzotti. 2015. Spreading holiday spirit and northwestern salamanders, Ambystoma gracile (Baird 1859) (Caudata: Ambystomatidae), Across the USA. IRCF Reptiles & Amphibians 22(3):126-127.

Stebbins, R.C. and McGinnis, S.M. 2012. Amphibians and reptiles of California. Revised edition. California Natural History Guides, Berkeley, CA.

Author: Daniel, W. M.

Revision Date: 8/28/2019

Peer Review Date: 8/28/2019

Citation Information:
Daniel, W. M., 2021, Ambystoma gracile (Baird, 1859): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=2946, Revision Date: 8/28/2019, Peer Review Date: 8/28/2019, Access Date: 3/8/2021

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2021]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [3/8/2021].

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