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BC Conservation Data Centre: Species Summary


Actinemys marmorata
Northwestern Pond Turtle

 
Scientific Name: Actinemys marmorata (Baird and Girard, 1852)
Scientific Name Synonyms: Clemmys marmorata
Emys marmorata
English Name: Northwestern Pond Turtle
English Name Synonyms: Western Pond Turtle
 
Classification / Taxonomy
Scientific Name - Concept Reference: Collins, J. T. 1990. Standard common and current scientific names for North American amphibians and reptiles. 3rd ed. Society for the Study of Amphibians and Reptiles. Herpetological Circular No. 19. 41 pp.
Classification Level: Species
Taxonomy Comments: Nov. 8, 2005: Moved from genus Emys to Actinemys. See Global Taxonomy Comment for more information.

Feb 21, 2005: Changed to Emys marmorata from Clemmys marmorata to align with NatureServe (DDW).
Species Group: Vertebrate Animal
Species Code: R-ACMA
Kingdom Phylum Class Order Family
Animalia Craniata Chelonia Testudines Emydidae
   
Conservation Status / Legal Designation
Global Status: G2 (Jan 2024)
Provincial Status: SX (Mar 2025)
BC List: Red
Provincial FRPA list:   
Provincial Wildlife Act:
COSEWIC Status: Extirpated (May 2023)
SARA Schedule: 1  -  Extirpated (Jan 2005)
General Status Canada: .2 - Extinct (2005)
   
Ecology & Life History
General Description: Carapace is low and olive, dark brown, or blackish, usually with a pattern of dark radiating spots or lines on each scute. Plastron is yellowish, often with dark blotching; top of head has black spots or network. Adult males differ from adult females in having the vent posterior to the rear edge of the carapace (vs. at or anterior to the carapace edge), a paler throat, and a shell that usually is flatter and less heavily marked. Young are brown or olive above, with yellow on the edge of the marginals and on the head, limbs, and tail; tail of young is nearly as long as the shell. Adult carapace length usually 9-19 cm (Stebbins 1985).
Global Reproduction Comments: Females can take between 6-12 years to mature, depending on site conditions (Ernst and Lovich 2009). Males generally mature sveral years sooner (Ernst and Lovich 2009). Copulation takes place from April to August (Ernst and Lovich 2009). Nesting occurs from April through August with peak nesting activity from late May to July (Holland 1994, Ernst and Lovich 2009). Clutch size generally increases with body size and can be from 1-13 eggs, with one or two clutches per season (Ernst and Lovich 2009).
Global Ecology Comments: Average home range sizes in a northern California stream were 0.25 ha along 248 m of stream length (females), 0.36 ha along 363 m of stream (juveniles), and 0.98 ha along 976 m of stream (males) (Bury 1972). Population densities vary widely between sites, but can be as high as 1,000 turtles per hectare (Ernst and Lovich 2009). Predators include a large variety of native mammals, birds, fishes, frogs, and snakes (Ernst and Lovich 2009). Invasive American bullfrogs (Lithobates catesbaei) and largemouth bass (Micropterus salmoides) are predators of juvenile turtles (Bury and Germano 2008, Ernst and Lovich 2009, Manzo et al. 2021, Gregory et al. 2024). A recently discovered infectious disease, pond turtle shell disease fungus (Emydomyces testavorans), can significantly decrease the structural integrity of shells (Lambert et al. 2021, Manzo et al. 2021).
Migration Characteristics:
(Global / Provincial)		 
    Nonmigrant:
    Local Migrant:
    Distant Migrant:
    Within Borders Migrant: 		N /
Y /
N /
na /
Global Migration Comments: During summer movements between pools of water in a northern California stream system, average movements were 142 m, 169 m, and 354 m for juveniles, females, and males, respectively (Bury 1972). Males are much more likely to travel distances over 200 m within water bodies (Bury 1972). Documentation of long-distance overland movements include 1.6 km in northern California (Bury 1972) and 5 km in northern Oregon (Holland 1994). In the Trinity River, northern California, turtles traveling to terrestrial refugia moved an average of 203 m from water with a maximum of 500 m (Reese and Welsh 1997).
Habitats:
(Type / Subtype / Dependence) 		Lakes / Lake / Unknown
Lakes / Pond/Open Water / Unknown
Stream/River / Stream/River / Unknown
Wetland / Marsh / Unknown
Wetland / Swamp / Unknown
Global Habitat Comments: Aquatic habitats include a wide variety of permanent and semi-permanent water bodies (Ernst and Lovich 2009, Germano 2016, Bury 2017). Naturally-occurring habitats include rivers, creeks, small lakes, ponds, and marshes (Ernst and Lovich 2009, Germano 2016, Bury 2017). Occasionally, this turtle is found in brackish water (Ernst and Lovich 2009). Substantial populations can exist in a variety of man-made or man-modified aquatic habitats in rural and urban settings including reservoirs, canals, cattle ponds, and sewage-treatment ponds (Spinks et al. 2003, Germano 2010, Ashton et al. 2015, Germano 2016, Davidson and Alvarez 2020, Germano 2020, Germano 2021, Manzo et al. 2021, Fulton et al. 2022). Preferred sites within a given water body generally involve deeper pools and sections with ample basking sites such as logs, rocks, or floating mats of vegetation (Ernst and Lovich 2009). When disturbed, basking turtles flee underwater (Ernst and Lovich 2009). In the northern and central part of the range, many individuals overwinter in upland habitats (Bury 1972, Holland 1994, Reese and Welsh 1997, Ernst and Lovich 2009). Nesting sites often have open canopies and can include sandy banks and bars along water bodies, or in fields or sunny spots up to a few hundred meters from water (Nussbaum et al. 1983, Storer 1930, Lovich and Meyer 2002, Ernst and Lovich 2009).
Food Habits: Carnivore: Adult, Immature
Invertivore: Adult, Immature
Piscivore: Adult, Immature
Global Food Habits Comments: This species is considered a dietary generalist. Food items can include algae, plants, snails, crustaceans, isopods, insects of various orders, other arthropods, earthworms, frogs, and carrion (Ernst and Lovich 2009).
Global Phenology: Hibernates/aestivates: Adult, Immature
Global Phenology Comments: The seasonal activity period varies geographically with southeastern populations active year-round while more northern populations overwinter in terrestrial refugia or permanent pools of water (Ernst and Lovich 2009). Some individuals may spend half the year in terrestrial habitat (Ernst and Lovich 2009). However, not all individuals of any given population overwinter in refugia (Ernst and Lovich 2009). Basking activity begins as soon as sunrise, but generally peaks before midday (Ernst and Lovich 2009).
Provincial Phenology:
(1st half of month/
2nd half of month)
Colonial Breeder: N
Length(cm)/width(cm)/Weight(g): 18/ /
Elevation (m) (min / max): Global: 
Provincial: 
   
 
Distribution
Endemic: N
Global Range Comment: This species occurs in northwestern United States, ranging from Puget Sound, Washington southward with a coastal (western) southern limit at the north end of San Francisco Bay, California and an interior (eastern) southern limit that extends down the west side of the Sierra Nevada (Bury and Germano 2008, Ernst and Lovich 2009, Spinks et al. 2014). A disjunct population in western Nevada has long been suspected of being introduced, although there are fossil records and a potential migration route has been proposed (Bury 2017). It is presumed extirpated from all historical sites in southern British Columbia, Canada (Ernst and Lovich 2009, Barela and Olson 2014). Using post-2004 (the past 20 years) records within the range of A. marmorata (sensu stricto) from Global Biodiversity Information Facility (2024), range extent was estimated to be 378,896 kmē (GeoCat 2024).

This species formerly included a subspecies that is now recognized as a full species, Actinemys pallida, ranging along the Coastal Range south of San Francisco Bay into northern Mexico (Spinks et al. 2014).
 
Authors / Contributors
Global Information Author: Hammerson, G. (2011); rev. R. L. Gundy (2024)
Last Updated: Feb 11, 2024
Provincial Information Author:
Last Updated:
   
References and Related Literature
Andelman, S. J., and E. Gray. 1992. Viability and recovery of western pond turtle (Clemmys marmorata) populations in Washington state. Abstract, Society for Conservation Biology, 6th Annual Meeting, p. 33.
Backhouse, F. 2000. Extinct and Extirpated Species. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 6pp.
Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.
Brattstrom, B. H., and D. F. Messer. 1988. Current status of the southwestern pond turtle, Clemmys marmorata pallida, in southern California. Final Report for California Department of Fish and Game, Contract C-2044. 47 pp. + xii.
Bury, R. B. 1970. Clemmys marmorata. Cat. Am. Amph. Rep. 100.1-100.3.
Bury, R. B. 1972. Habits and home range of the Pacific pond turtle, Clemmys marmorata, in a stream community. Ph.D. dissertation, Univ. California, Berkeley.
Bury, R. B. 1979. Population ecology of freshwater turtles. Pages 571-602 in M. Harless and H. Morlock, editors. Turtles: perspectives and research. John Wiley & Sons, Inc. Reprinted in 1989 by Robert E. Krieger Publ. Co., Malabar, Florida.
Bury, R. B. 1986. Feeding ecology of the turtle, Clemmys marmorata. J. Herpetol. 20:515-521.
Buskirk, J. R. 1990. Geographic distribution: Clemmys marmorata. SSAR Herpetol. Rev. 21(1):26.
COSEWIC. 2002i. COSEWIC assessment and status report on the Pacific pond turtle Clemmys marmorata in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa.
vi + 17 pp.
Ernst, C. H., and R. W. Barbour. 1972. Turtles of the United States. Univ. Press of Kentucky, Lexington. x + 347 pp.
Ernst, C. H., and R. W. Barbour. 1989a. Turtles of the world. Smithsonian Institution Press, Washington, D.C. xii + 313 pp.
Ernst. C. H., and J. E. Lovich. 2009. Turtles of the United States and Canada. Second edition, revised and updated. Johns Hopkins University Press, Baltimore, Maryland. xii + 827 pp.
Gregory, P.T., and R.W. Campbell. 1984. The Reptiles of British Columbia. Royal B.C. Mus. Handb. 102pp.
Holland, D. C. 1994. The western pond turtle: habitat and history. U.S. Department of Energy, Bonneville Power Administration, Portland, Oregon. 11 chapters + appendices.
Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho, Moscow, Idaho. 332 pp.
Reese, D. A., and H. H. Welsh, Jr. 1997. Use of terrestrial habitat by western pond turtles, Clemmys marmorata: implications for management. Pages 352-357 in J. V. Abbema, editor. Proceedings: conservation, restoration, and management of tortoises and turtles--an international conference. New York Turtle and Tortoise Society and Wildlife Conservation Society, New York.
Seeliger, L. M. 1945. Variation in the Pacific mud turtle. Copeia 1945(3):150-159.
Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
Storer, T. I. 1930. Notes on the range and life-history of the Pacific fresh-water turtle, Clemmys marmorata. Univ. Calif. Publ. Zool. 32(5):429-441.
The Reptiles of British Columbia: Western (Northern Pacific) Pond Turtle, Emmys marmorata marmorata. 2004. Univ. Coll. of the Cariboo, and B.C. Minist. Water, Land and Air Prot. Online. Available: http://www.bcreptiles.ca/turtles/westernpond.htm
 

Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.

Suggested Citation:

B.C. Conservation Data Centre. 2024. Species Summary: Actinemys marmorata. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 6, 2026).