The Western pond turtle (''Actinemys marmorata''), also known commonly as the Pacific pond turtle is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of small to medium-sized

turtle Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked t ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Emydidae Emydidae (Latin ''emys'' (freshwater tortoise) + Ancient Greek εἶδος (''eîdos'', “appearance, resemblance”)) is a family of testudines (turtles) that includes close to 50 species in 10 genera. Members of this family are commonly calle ...

. The species is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the western coast of the United States and Mexico, ranging from western Washington state to northern

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

. It was formerly found in

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

(in

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...

), but in May 2002, the Canadian Species at Risk Act listed the Pacific pond turtle as being extirpated.

Taxonomy and systematics

Its genus classification is mixed. ''

Emys ''Emys'' is a small genus of turtles in the family Emydidae. The genus (''sensu lato'') is endemic to Europe and North America. Species The following two species may be assigned to the genus ''Emys'' (''sensu lato''). ''Nota bene'': A binom ...

'' and '' Actinemys'' were used among published sources in 2010. It was known by several names in the Indigenous languages of its range, including kʰá:wanaka: ( Northeastern Pomo), kʰa:wana (

Southern Pomo Southern Pomo is one of seven mutually unintelligible Pomoan languages which were formerly spoken and is currently spoken by the Pomo people in Northern California along the Russian River and Clear Lake. The Pomo languages have been grouped ...

), and ʔaləšək (

Lushootseed Lushootseed (txʷəlšucid, dxʷləšúcid), also Puget Salish, Puget Sound Salish or Skagit-Nisqually, is a language made up of a dialect continuum of several Salish tribes of modern-day Washington state. Lushootseed is one of the Coast Salis ...

Description

The dorsal color of ''A. marmorata'' is usually dark brown or dull olive, with or without darker reticulations or streaking. The plastron is yellowish, sometimes with dark blotches in the centers of the scutes. The straight

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

length is . The carapace is low and broad, usually widest behind the middle, and in adults is smooth, lacking a keel or serrations. Adult western pond turtles are sexually dimorphic, with males having a light or pale yellow throat.

Distribution

The western pond turtle originally ranged from northern

, Mexico, north to the southern regions of

, Canada. It was once a large part of a major fishery on Tulare Lake, California, supplying San Francisco with a local favorite, turtle soup, as well as feed for hogs that learned to dive for it in the shallows of Hog Island, also on Tulare Lake. As of 2007, it has become rare or absent in the

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected m ...

region of

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

. It has a disjunct distribution in most of the Northwest, and some isolated populations exist in southern Washington. The western pond turtle is now rare in the

Willamette Valley The Willamette Valley ( ) is a long valley in Oregon, in the Pacific Northwest region of the United States. The Willamette River flows the entire length of the valley and is surrounded by mountains on three sides: the Cascade Range to the eas ...

north of

Eugene, Oregon Eugene ( ) is a city in the U.S. state of Oregon. It is located at the southern end of the Willamette Valley, near the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast. As of the 2020 United States Census, ...

, but abundance increases south of that city where temperatures are higher. It may be locally common in some streams, rivers and ponds in southern Oregon. A few records are reported east of the

Cascade Mountains The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, a ...

, but these may have been based on introduced individuals. It ranges up to in Washington, and to about in Oregon. It also occurs in Uvas Canyon area, Santa Cruz Mountains, California, and in the North Bay, and lakes such as

Fountaingrove Lake Fountaingrove Lake is a reservoir in the city of Santa Rosa, California, United States. Formed by the Fountaingrove Dam, the lake is fed from the east by Piner Creek, which is also the lake's sole outlet. Fountaingrove Dam is an earthen dam b ...

. Many taxonomic authorities now split what had been considered one species of turtle into two species. The southern species is named '' Actinemys pallida'', or the southwestern pond turtle. Its range is southern California and Mexico. The northern species remains ''Actinemys marmorata'', with a range of northern California northward. It is then usually referred to as the northwestern pond turtle.

Ecology and behavior

The western pond turtle occurs in both permanent and intermittent waters, including marshes, streams, rivers, ponds, and lakes. It favors habitats with large numbers of emergent logs or boulders, where individuals aggregate to bask. They also bask on top of aquatic vegetation. Consequently, this species is often overlooked in the wild. However, it is possible to observe resident turtles by moving slowly and hiding behind shrubs and trees. ''A. marmorata'' can be encouraged to use artificial basking substrate, or rafts, which allows for easy detection of the species in complex habitats. In addition to its aquatic habitat, terrestrial habitat is also extremely important for the western pond turtle. Since many intermittent ponds can dry up during summer and fall months along the west coast, especially during times of drought, the western pond turtle can spend upwards of 200 days out of water. Many turtles overwinter outside of the water, during which time they often create their nests for the year.

Diet

The western pond turtle is

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...

and most of its animal diet includes insects, crayfish, and other aquatic invertebrates. Fish, tadpoles, and frogs are eaten occasionally, and carrion is eaten when available. Plant foods include filamentous algae, lily pads, tule and cattail roots. Juveniles are primarily carnivorous, and eat insects and carrion. At about age three they begin to eat plant matter.

Predation and threat

Raccoons, otters, ospreys, and coyotes are the biggest natural threats to this turtle, its eggs, and hatchlings. Weasels and large fish are also known predators. , Non-native predators include bullfrogs, crayfish, and opossums. In the past the turtle was exploited as food by both indigenous peoples and American settlers. After the goldrush in California a large "fishery" emerged processing turtles from the San Francisco Bay Estuary into canned soup for markets East. Finally, this species is still threatened by humankind. Due to

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and modification, this species is currently listed as vulnerable on the IUCN Red List. It also faces significant competition from introduced invasive species, especially the Red-Eared Slider. With the removal of ponds, modification of sandy banks needed for egg laying, draining of wetlands, this species is now vulnerable. Efforts at reintroducing this turtle to its native range have met with limited success.

Reproduction

Sexually mature females of the western pond turtle produce 5–13 eggs per

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

. They deposit eggs either once or twice a year. They may travel some distance from water for egg-laying, moving as much as 0.8 km (1/2 mile) away from and up to above the nearest source of water, but most nests are within of water. The female usually leaves the water in the evening and may wander far before selecting a nest site, often in an open area of sand or hardpan that is facing southwards. The nest is flask-shaped with an opening of about . Females spend considerable time covering up the nest with soil and adjacent low vegetation, making it difficult for a person to find unless it has been disturbed by a predator.

Hatchlings

The vast majority of western pond turtle hatchlings overwinter in the nest, and this phenomenon seems prevalent in most parts of the range, especially northern areas. This might explain the difficulty researchers have had in trying to locate hatchlings in the fall months. Winter rains may be necessary to loosen the hardpan soil where some nests are deposited. It may be that the nest is the safest place for hatchlings to shelter while they await the return of warm weather. Whether it is hatchlings or eggs that overwinter, young first appear in the spring following the year of egg deposition. Individuals grow slowly in the wild, and their age at their first reproduction may be 10 to 12 years in the northern part of the range. The western pond turtle may survive more than 50 years in the wild.

References

Bibliography

*Holland, Dan C., PhD. The Western Pond Turtle: Habitat and History, Final Report. U.S. Department of Energy, Bonneville Power Administration, Division of Fish and Wildlife; Wildlife Diversity Program, Oregon Department of Fish and Wildlife, August 1994. * *