Western Pond Turtle

Location

In the Zoo

Scientific Information

Scientific Name: Actinemys marmorata
Class: Reptilia
Order: Testudines
Family: Emydidae
Genus: Emys

Size

Male

Female

Height:
Length: 4-6 inches 5-7 inches
Weight: 1-2.4 pounds 1-2.4 pounds
Maturity: 8-14 years 8-14 years

Lifestyle and Lifespan

Diet: Omnivorous
Activity Timeframe: Diurnal
Interactivity: Solitary
Sexual Dimorphism: Yes
Gestation: 90-130 days
Lifespan in the Wild: 50 years
Lifespan in Captivity: 40-80 years

Geographic Range

North America, West Coast; from Baja, Mexico to Washington state

Conservation

Status in the Wild: Vulnerable
Threats: Introduced Species

Characteristics

California's only native aquatic freshwater turtle! The low, broad, smooth carapace is usually light to dark brown or olive in color, with lighter marbling visible on closer inspection. However, the shell color and markings can vary greatly. The markings are prevalent in young turtles and typically fade with age. (However, there are occurrences of old individuals with irregular whitish patches on the shells, necks and heads.) The limbs and head are olive, yellow, orange or brown, often with darker flecks or spots.

Species Specifics

The two subspecies of these turtles are the Northwestern Pond Turtles (Actinemys marmorata marmorata), found in areas north of the American River in California and the Southwestern Pond Turtles (Actinemys marmorata pallida), found in areas south of San Francisco.This species also exhibits sexual dimorphism. Females are larger, and their shell is more raised than the male. Males also tend to have yellow throats and thicker tail bases.

Physical Characteristics

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Ecology

Habitat

These turtles mostly prefer serene streams, ponds, marshes, muddy canals, calm lakes and pools as their natural habitat. Sometimes they may also wander into upland areas almost half a kilometer away from water.

Distribution

The northwestern subspecies ranges from southern British Columbia south to central California, while the southwestern subspecies tends to be coastal, and ranges northward from northern Mexico to the San Francisco peninsula. The two subspecies intersect in the Central Valley, from north of Sacramento to Kern County going south.

Diet

Omnivore. Their main diet consists of water plants, algae crustaceans, midges, dragonflies, beetles, stoneflies and caddisflies. Western Pond Turtles are also opportunistic and occasionally scavenge on mammal, bird, reptile, amphibian and fish carrion. Some sources say that males tend to eat more insects and vertebrates and females eat more algae and other plant material.

Ecological Web

Secondary consumer.Western pond turtles are prey for many other species. They also act as hosts for several parasitic organisms.

Activity and Behavior

Activity Pattern

Female turtles stay in the nest chamber during incubation. Incubation take approximately 3 months, with most hatchlings staying in the nest chamber until the following spring. (Although, some hatchlings in southern and central California emerge in the fall.)

Behavior

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Social Behavior

Western pond turtles are not generally territorial, although aggressive encounters (like ramming, biting and threatening with open-mouth gestures), are common over basking areas. Turtles tend to hunt late in the day and bask intermittently in order to maintain an average body temperature of 28 degrees Celsius.

Reproductive Behavior

Western pond turtle males court females using their forelimbs to scratch the anterior edge of the female's carapace. This is followed by the female raising her posterior end, after which mating occurs. (Due to the isolated nature of these animals, there is not much known about the mating process.)Western pond turtles mate from May through August, with most females laying eggs in alternating years. Although the average age of maturity is between 8 and 14 years of age.Females deposit eggs in a nest they dig on land at night. After incubation, hatchlings leave the egg only if the temperature is below 81 degrees Fahrenheit. Hatchlings tend to be male if the incubation temperature was below 86 degrees Fahrenheit, and female if the incubation temperature was above 86 degrees Fahrenheit. Hatchlings immediately return to the water to grow. The turtle's growth is accompanied by darkening of the body and hardening of the shell. (Growth rate largely depends on external environmental factors, such as water, temperature and food abundance. Colder water and less food slows the growth rate.)Nests are built up from the water. Hatching success rates are approximately 70%, as there is a high rate of nest predation and complete nest failure. Nests are generally found in flat areas with low vegetation and dry, hard soil. Incubation takes about 3 months, with most hatchlings staying in the security of the nest chamber until the next spring. (Some hatchlings in southern and central California emerge in the fall.)And, after the eggs are laid, there is no evidence of parental care.

Offspring

1-3 offspring

Conservation

Status

Currently listed as Vulnerable by the IUCN.US Fish and Wildlife consider the Western Pond Turtle a species of special concern, and California state law protects them. The northern populations have virtually disappeared in some ranges!Western Pond Turtles are an important part of the North American ecosystem. Over the years their numbers have been greatly reduced due to predation, fragmentation and habitat destruction.Commercial harvest or taking of Western Pond Turtles has been prohibition in all U.S. states where they are found since the 1980's. It's listed as an endangered species in Washington state, and protected in Oregon and California. The recent increase in stock ponds and other man-made water sources appears to have had a positive impact on population numbers and a few "head-start" programs claim to have had excellent survivorhship rates after being released into the wild. ("Head-start programs are where the young turtles are raised in captivity until their shells begin to harden and they are less acceptable to predation. However, re-introduction is limited if the habitat of the species is not protected.)

Historical

Current Threats

Introduced Species

Our Role

Oakland Zoo's Headstart Program: The Oakland Zoo is raising hatchlings right here at the Zoo in our Biodiversity Center! With our zookeepers taking care of these baby turtles with plenty of nutrient-rich foods and veterinary care, they grow in just one year to the size it would take them three or four years to reach in the wild. Then, when we release them into the wild they are big enough to protect themselves and have a much better chance of survival!Each summer our zookeepers team up with biologists and students from Sonoma State University to study the Western Pond Turtle. Out in the field, the Zoo does things like: incubate nests in the field and use telemetry equipment to track nesting females.Learn more at http://www.oaklandzoo.org/Western_Pond_Turtle.php

How You Can Help

-Don;t release pet turtles into the wild.-Help keep our lakes and watersheds clean welcoming places for Western Pond Turtles.-Be sure to teach others all about the amazing Western Pond Turtle!

Fascinating Facts

The shape of a turtle's carapace indicates how much time it normally spends in the water: individual's spending more time on land will have a more rounded carapace while those with a flat carapace often spend their time in the water.

Western Pond Turtles are the only turtles belonging to the genus "Actinemys."

Western Pond Turtles are normally quiet, but will produce a high-pitched crying sound when threatened.

Their latin name 'marmorata' refers to the marbled pattern of both the soft parts and shell of many Western Pond Turtles.

The external temperature around the egg during incubation can determine whether the turtle is born male or female!

References

Buskirk, J. 2002. "The western pond turtle, Emys marmorata" (On-line) Radiata: Journal of DGHT-AG Schildkroten English Edition, 11:3-30. Accesssed February 3, 2017 at www.pondturtle.com/Buskirk,%20James%20R.%202002.pdf

Nachman, J. 2008. "Emys marmorata" (On-line), Animal Diversity Web. Accessed February 3, 2017 at http://animaldiversity.org/accounts/Emys_marmorata/

U.S. Department Of The Interior. 1999. "Western Pond Turtle: Clemmys marmorata." California: Bureau Of Land Management. (On-line) Accessed February 3, 2017 at http://www.blm.gov/ca/pdfs/cdd_pdfs/clemmys1.pdf

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9777 Golf Links Road Oakland, CA 94605