The Western pond turtle is a medium-sized turtle native to the western coast of the United States and Mexico. They are usually dark brown or dull olive in color, with or without darker reticulations or streaking. The plastron is yellowish, sometimes with dark blotches in the centers of the scutes. 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 light or pale yellow throat.
Western pond turtles are found in the western coast of the United States and Mexico, ranging from western Washington state to northern Baja California. They live in marshes, streams, rivers, ponds, and lakes.
Western pond turtles are generally solitary semi-aquatic creatures. They spend most of their lives in water, however, they require terrestrial habitats for nesting. These turtles favor habitats with large numbers of emergent logs or boulders, where they aggregate to bask. They also bask on top of aquatic vegetation. Since many ponds can dry up during summer and fall months along the west coast, especially during times of drought, 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. In some areas, Western pond turtles brumate (hibernation-like state) during the winter months. During brumation, they will burrow into the mud above or below the water and remain inactive until it gets warm again. Western pond turtles are diurnal and usually hunt late in the day. They are very shy and when sense danger will dive into the water. In order to protect themselves, they quickly hide their head and legs into their hard shell.
Western pond turtles are omnivorous. Most of the 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.
Little is known about the reproductive behavior of Western pond turtles. They breed in the spring and sometimes in the fall. Females produce 5-13 eggs per clutch. They may travel some distance from water for egg-laying, moving as much as 0.8 km (1/2 mile) away. 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 (2 in). 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. The eggs will incubate for 90-130 days. Hatchlings are well-developed and independent at birth. They usually overwinter in the nest because the nest is the safest place for them to shelter while they await the return of warm weather. Hatchlings grow slowly in the wild and become reproductively mature between 10 and 12 years of age.
Western pond turtles face many threats including habitat destruction due to urbanization, disease, fire, flooding, and droughts. These turtles have a very slow reproduction and although they live up to 50 years, they reproduce slowly. It takes around 10 years for females to become reproductively mature and when mature, they lay only 5-13 eggs a year. So the loss of only a few adults can also influence the rapid decline of the Western pond turtle populations.
The IUCN Red List and other sources don’t provide the number of the Western pond turtle total population size. Currently, this species is classified as Vulnerable (Vu) on the IUCN Red List.
Due to feeding upon various invertebrates and insects, Western pond turtles control the numbers of these species’ populations throughout the area of their habitat.