Ambystoma gracile - (Baird, 1857 [1859])
Northwestern Salamander
Other English Common Names: northwestern salamander
Taxonomic Status: Accepted
Related ITIS Name(s): Ambystoma gracile (Baird, 1859) (TSN 173597)
French Common Names: salamandre foncée
Unique Identifier: ELEMENT_GLOBAL.2.103251
Element Code: AAAAA01040
Informal Taxonomy: Animals, Vertebrates - Amphibians - Salamanders
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Caudata Ambystomatidae Ambystoma
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.
Concept Reference Code: B85FRO01HQUS
Name Used in Concept Reference: Ambystoma gracile
Taxonomic Comments: Titus (1990) concluded that available genetic and morphological information do not support recognition of subspecies; systematics may be complex and warrant further study. Titus and Gaines (1991) studied allozyme variation in coastal metamorphosing and montane nonmetamorphosing populations in Oregon; in both groups of populations, 98-100% of the total genetic variation for each locus was attributable to within-population variation. See Kraus (1988) and Shaffer et al. (1991) for phylogenetic analyses of North American Ambystoma; allozyme data indicate that A. maculatum is the closest relative of A. gracile (Shaffer et al. 1991), a conclusion that is not supported by any morphological data (Kraus 1988).
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 10May2016
Global Status Last Changed: 03Oct2001
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Many stable populations exist throughout the historical range in the Pacific Northwest; not acutely sensitive to modern timber harvest practices; can coexist with introduced fishes and bullfrogs.
Nation: United States
National Status: N5 (05Nov1996)
Nation: Canada
National Status: N4N5 (10May2016)

U.S. & Canada State/Province Status
United States Alaska (S3), California (SNR), Oregon (S5), Washington (S5)
Canada British Columbia (S4S5)

Other Statuses

Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Not at Risk (01Apr1999)
Comments on COSEWIC: Reason for Designation: This salamander species has a limited and fragmented range and a low effective population size due to fluctuations. Reliance on ephemeral ponds for breeding leave it vulnerable to development. Nevertheless, it may be locally abundant and is not currently in decline.

Status History: Designated Not at Risk in April 1999. Added to the high priority Candidate list on 2015-11-18.
 

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: Range includes the Pacific coast of North America from extreme southeastern Alaska south through western Canada and the northwestern United States (mainly west of the Cascades) to the Gualala River, California, at elevations from sea level to about 10,200 feet (3,110 meters) (Stebbins 2003).

Area of Occupancy: Unknown 4-km2 grid cells
Area of Occupancy Comments:  

Number of Occurrences: 81 - 300
Number of Occurrences Comments: This species is represented by many occurrences (subpopulations).

Population Size: 10,000 - 1,000,000 individuals
Population Size Comments: Total adult population size is unknown but surely exceeds 10,000 and possibly exceeds 100,000.

Number of Occurrences with Good Viability/Integrity: Unknown

Overall Threat Impact: Unknown
Overall Threat Impact Comments: Ambient ultraviolet radiation causes increased mortality of eggs (compared to UV-B-shielded eggs) (Blaustein et al. 1995), but natural oviposition sites often may not be subject to damaging levels of UV.
Experimental data indicate that larvae are negatively impacted by the presence of trout (Tyler et al. 1998), yet salamanders and trout coexist in some areas (Leonard et al. 1993). Embryos in egg masses easily survive several weeks of prolonged exposure to air as may occur with recession of water level in breeding ponds (Marco 2001).

Short-term Trend: Unknown

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: Over the long term, extent of occurrence, area of occupancy, number of subpopulations, and population size probably have been relatively stable or have declined by less than 25 percent.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Range includes the Pacific coast of North America from extreme southeastern Alaska south through western Canada and the northwestern United States (mainly west of the Cascades) to the Gualala River, California, at elevations from sea level to about 10,200 feet (3,110 meters) (Stebbins 2003).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AK, CA, OR, WA
Canada BC

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: IUCN, Conservation International, NatureServe, and collaborators, 2004


U.S. Distribution by County Help
State County Name (FIPS Code)
AK Prince of Wales-Outer Ketchikan (CA) (02201)*, Skagway-Hoonah-Angoon (CA) (02232), Wrangell-Petersburg (CA) (02280)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
19 Ketchikan (19010102)+*, Mainland (19010201)+, Baranof-Chichagof Islands (19010203)+, Glacier Bay (19010302)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A large salamander.
Reproduction Comments: Breeding season is variable; begins as early as January in south, extends as late as July in north or at higher elevations. Lays masses of 15-35 eggs or 100-200 eggs, which hatch in 2-4 weeks. Larval period lasts 1-2 years. Montane populations often paedomorphic, some obligately so; incidence of paedomorphosis is positively correlated with increasing elevation, stability of the aquatic habitat, lack of fishes, and slower larval growth rates. Metamorphic and paedomorphic individuals may coexist in the same population.
Ecology Comments: Preyed on by introduced trout, which reduce salamander abundance.
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Nonpaedomorphic populations migrate between breeding and nonbreeding habitats; usually migrates on rainy nights.
Riverine Habitat(s): CREEK, Pool, SPRING/SPRING BROOK
Lacustrine Habitat(s): Deep water, Shallow water
Palustrine Habitat(s): TEMPORARY POOL
Terrestrial Habitat(s): Forest - Conifer, Forest - Hardwood, Forest - Mixed, Grassland/herbaceous, Woodland - Conifer, Woodland - Hardwood, Woodland - Mixed
Special Habitat Factors: Benthic, Burrowing in or using soil, Fallen log/debris
Habitat Comments: Open grassland, woodland, and forest near breeding ponds. Nonpaedomorphic adults are underground most of the year. During the breeding season, they often are found under rocks and logs. Larvae have been reported to be restricted to shallows in lakes with fishes, but adult and larval northwestern salamanders are distasteful to fishes and bullfrogs, allowing coexistence (Leonard et al. 1993). Eggs are laid in ponds, lakes, and slow-moving streams; usually attached to vegetation in shallows (Blaustein et al. 1995) or deeper water (e.g., 0.5-1.0 m below water surface) (Nussbaum et al. 1983).
Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food Comments: Larvae feed on zooplankton as well as many other aquatic invertebrates. Diet of terrestrial adults is not well documented, but they apparently feed on a wide variety of terrestrial invertebrates (Nussbaum et al. 1983).
Adult Phenology: Circadian, Hibernates/aestivates, Nocturnal
Immature Phenology: Circadian, Hibernates/aestivates, Nocturnal
Phenology Comments: Nonpaedomorphic adults seldom seen except when breeding. Active day and night in deep water where fish absent; strictly nocturnal where fish present (Taylor 1984).
Colonial Breeder: Y
Length: 22 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Management Requirements: In Washington, a lake population increased after removal of non-native fishes (Hoffman et al. 2004).
Population/Occurrence Delineation
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Group Name: Ambystomatid Salamanders

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including larvae or eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Heavily traveled road, especially at night during salamander breeding season, such that salamanders almost never successfully traverse the road; road with a barrier that is impermeable to salamanders; wide, fast rivers; areas of intensive development dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 3 km
Separation Justification: BARRIERS/UNSUITABLE HABITAT: Rivers may or may not be effective barriers, depending on stream width and hydrodynamics; identification of streams as barriers is a subjective determination. Bodies of water dominated by predatory fishes have been described as barriers but probably should be regarded as unsuitable habitat. For A. barbouri, a stream-pool breeder, predatory fishes appeared to act as a barrier to larval dispersal and gene flow for populations separated by as little as 500-1000 m (Storfer 1999). Highly disturbed land, such as the cleared and bedded soils of some silvicultural site preparation, may serve as an impediment to movement of A. cingulatum (Means et al. 1996), although Ashton (1998) noted the species' use of pine plantations, pastures, and three-year-old clearcuts. Such areas should be treated as unsuitable habitat rather than barriers.

MOVEMENTS: Palis's (1997b) suggested use of 3.2 km between breeding sites to distinguish breeding populations of A. cingulatum was based on Ashton's (1992) finding that individuals may move as much as 1.6 km from their breeding ponds. Ambystoma californiense sometimes migrates up to 2 km between breeding ponds and terrestrial habitat (see USFWS 2004). Funk and Dunlap (1999) found that A. macrodactylum managed to recolonize lakes after trout extirpation despite evidence of low levels of interpopulation dispersal. Based on a review of several Ambystoma species (e.g., Semlitsch 1981, Douglas and Monroe 1981, Kleeberger and Werner 1983, Madison 1997), Semlitsch (1998) concluded that a radius of less than 200 meters around a breeding pond would likely encompass the terrestrial habitat used by more than 95 percent of adults. Faccio's (2003) study of radio-tagged A. maculatum and A. jeffersonianum in Vermont supports this conclusion. In New York, all movements of A. tigrinum occurred in areas within 300 m of the nearest breeding pond (Madison and Farrand 1998). However, most studies of these salamanders had small sample sizes and/or were not designed to detect long-distance movements, so migration distance may be somewhat underestimated.

In summary, ambystomatid salamanders generally stay within a few hundred meters of their breeding pool. Due to high breeding site fidelity and limitation of breeding to pool basins, populations using different breeding sites exhibit little or no interbreeding among adults. Thus one might argue that each pool constitutes a separate occurrence or that the separation distance for suitable habitat should be the nominal minimum of 1 km. However, little is known about how frequently first-time (or experienced) breeders use non-natal pools (pools from which they did not originate) or how far they may move to such sites. Frequent colonization of new and remote habitats by at least some species suggests that dispersal movements sometimes may be longer than typical adult migration distances. It seems unlikely that locations separated by a gap of less than a few kilometers of suitable habitat would represent independent occurrences over the long term.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .3 km
Inferred Minimum Extent Justification: Inferred extent distance pertains to breeding sites (with the center of the circle in the center of the breeding site). Most ambystomatids stay within a few hundred meters of their breeding pool (see separation justification section).
Date: 10Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 11Jan2008
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 19Sep1994
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Cook, F. R. 1984. Introduction to Canadian amphibians and reptiles. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Ontario.

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  • Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.

  • Frost, D. R. 2002. Amphibian Species of the World: an online reference. V2.21 (15 July 2002). Electronic database available at http://research.amnh.org/herpetology/amphibia/index.html.

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  • Hoffman, R. L., G. L. Larson, and B. Samora. 2004. Responses of Ambystoma gracile to the removal of introduced nonnative fish from a mountain lake. Journal of Herpetology 38:578-585.

  • Jones, T. R., A. G. Kluge, and A. J. Wolf. 1993. When theories and methodologies clash: a phylogenetic reanalysis of the North American ambystomatid salamanders (Caudata: Ambystomatidae). Systematic Biology 42:92-102.

  • Kraus, F. 1988. An empirical evaluation of the use of the ontogeny polarization criterion in phylogenetic inference. Systematic Zoology 37:106-141.

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