Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 32, Number 2;   February, 2005

The Western Pond Turtle

by Cat Murphy

Western Pond turtles are a medium-sized, dull colored turtle native to the Pacific Northwest. Originally ranging from Northern California to the Puget Sound in Washington, it appears this turtle species is now rare or even extinct in certain areas in Puget Sound and the Willamette Valley. Few turtles have been spotted around the areas where they used to be abundant. Possible threats to the Western Pond turtle's survival include invasive species, predation on eggs and hatchlings, disease, drought, and habitat destruction due to human construction.

The Western Pond turtle (Clemmys marmorata), also called the Pacific Terrapin, is rather drab in coloration; usually dark brown or olive, to blend in with its habitat. The plastron is typically yellowish and some turtles show .dark blotches. Reaching a size of between four and nine inches long, they have a wide shell in the middle, with smooth scaling. Male and female are usually easy to differentiate between, as the species is sexually dimorphic. The throat of the male Western Pond turtle is light or yellow in coloration, whereas the throat of the female is brown with dark spotting. Males also have a more concave plastron compared to the females, whose plastron is more convex.

These turtles prefer environments with abundant basking platforms, such as logs or boulders sticking out of the water. They can be found in many aquatic areas, especially areas with lots of water-borne vegetation for them to hide amongst. Western Pond turtles have been found in a variety of habitats, including small streams, ponds (typical to their name), slow rivers, and lakes.

Basking is an important part of the Western Pond turtle's survival, as it provides thermoregulation for an animal that cannot form its own warmth. During basking, a game of "king of the mountain" is often played, and the turtles push each other around for the best basking location. These turtles are very alert, and have excellent eyesight and hearing, which makes them extremely hard to observe in the wild. Usually if they are alerted to danger, every turtle will immediately plunge into the water and dive to the bottom, to wait until the danger passes. However; if one waits quietly and patiently, one might get a glimpse as one or more pop to the surface to survey that the danger is gone.

Western Pond turtles feed primarily on insects, amphibian eggs, and various aquatic plants, such as algae, lily-pods, and cattail roots. Being omnivorous, they have been observed feeding on crayfish, fish, tadpoles, frogs, water-borne carrion, and have been caught on baited hooks by fishermen on occasion.

Little is written about the mating habits of the Western Pond turtle, but it is known that females lay between five and thirteen eggs once a year (typically, 4-5 eggs). Some females will produce two clutches a year, but this is rare. The eggs are deposited in a land location, often up to three hundred feet from the source of water. Nest sites are usually located in a sunny, sandy area, oddly, facing southward. After the eggs are laid, the female covers the nest in sand and vegetation to hide the nest from predators.

The eggs hatch in seventy to one hundred and ten days. In more northern areas of pond turtle habitats, hatchlings will often spend their first winter in the nest. It is speculated that the winter rains may be necessary to free the babies from the soil, but this is not proven. The following spring, young turtles dig their way out of the nest, and make an often long journey to the nearest body of water to start their lives. Unfortunately, most hatchlings will not make it to adulthood, but those who do have the possibility of a long life of thirty or more years.

Sources cited:
St. John, Alan. Reptiles of the Northwest, Lone Pine, 2002.
Seattle Audubon Society. Reptiles of Washington & Oregon, SAS, 1995.
Society for NW Vertebrate Biology. Northwest Fauna, Number 3, 1954.