western pond turtle

Appearance

The dorsal color 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 shell is 11–21 cm in length. The dorsal shell 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; that is, males have a light or pale yellow throat.

Distribution

Western pond turtles originally ranged from northern Baja California, Mexico, north to the Puget Sound region of Washington. As of 2007, they have become rare or absent in the Puget Sound area. They have a disjunct distribution in most of the Northwest, and some isolated populations exist in southern Washington. Pond Turtles are now rare in the Willamette Valley north of Eugene, Oregon, but abundance increases south of that city where temperatures are higher. They may be locally common in some streams, rivers and ponds in southern Oregon. A few records are reported east of the Cascade Mountains, but these may have been based on introduced individuals. They range up to 305 m in Washington, and to about 915 m in Oregon.

Behavior

Western pond turtles occur in both permanent and intermittent waters, including marshes, streams, rivers, ponds, and lakes. They favor habitats with large numbers of emergent logs or boulders, where they aggregate to bask. They also bask on top of aquatic vegetation or position themselves just below the surface where water temperatures are elevated. Individuals display aggressive behavior toward one another while sunning. Western pond turtles will rapidly dive off basking sites when approached by humans, even at distances of over 50 m. 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.

Western pond turtles seek refuge in deep water, under submerged logs and rocks, in beaver burrows and lodges, and by "swimming" into deep silt. They are extremely difficult to detect under these conditions. Turtles can be encouraged to use artificial basking substrate, or rafts, which allows for easy detection of the species in complex habitats.

Habitat

Western pond turtles occur in both permanent and intermittent waters, including marshes, streams, rivers, ponds, and lakes. They favor habitats with large numbers of emergent logs or boulders, where they aggregate to bask. They also bask on top of aquatic vegetation or position themselves just below the surface where water temperatures are elevated. Individuals display aggressive behavior toward one another while sunning. Western pond turtles will rapidly dive off basking sites when approached by humans, even at distances of over 50 m. 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.

Western pond turtles seek refuge in deep water, under submerged logs and rocks, in beaver burrows and lodges, and by "swimming" into deep silt. They are extremely difficult to detect under these conditions. Turtles can be encouraged to use artificial basking substrate, or rafts, which allows for easy detection of the species in complex habitats.

Reproduction

Females produce 5-13 eggs per clutch. 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 away from and up to 90 m above the nearest source of water, but most nests are with 90 m 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 5 cm . 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.

Food

Western pond turtles are omnivorous and most of their animal diet includes insects, crayfish and other aquatic invertebrates. Fishes, tadpoles, and frogs are eaten occasionally, and carrion is eaten when available. Plant foods include filamentous algae, lily pads, tule and cattail roots.