by Emma Hurley, Scientific Technician …
NORTHERN WESTERN POND TURTLE Actinemys warmorata
Winter, spring and into summer, field projects have been getting our technicians out and about all over the watershed. From the large volume main-stem to tiny tributaries high up in the watershed we have been running into beautiful Western Pond Turtles left and right!
The native turtle on the Gualala River is the Northern Western Pond Turtle (also known as the Pacific Pond Turtle). They are small to medium-sized (3.5 – 8.5 inches in shell length) and are drab colored brown/blackish/olive green with spots on the head and legs and a pattern of lines or spots radiating from the centers of the scutes (plates on the shell). Their shell, or carapace, is a low dome and not keeled.
They are diurnal, and while they are aquatic, they can wander from the water edge in search of food or to lay eggs. We commonly found them walking along dirt roads 200-500′ from the river during breeding and egg-laying season- April to May. They spend much of the sunny part of the day basking above the water on rocks and logs. They are mostly active from around February, when temperatures start to warm up, to November.
Very CRAZY fun-fact: pond turtles hibernate underwater for several months in the winter. During summer droughts when water runs low they will bury themselves in soft bottom mud.
Pond turtles do not sexually mature until eight to ten years old and lay 2-11 eggs between April- August. Females climb onto land to dig a nest. Some females lay two clutches in a year while others lay eggs every other year
CONSERVATION: The Western Pond Turtle is in decline in around 75 – 80% of its range.
Western Pond Turtles were harvested for food from the 1800s- 1930s. They were eaten locally and sold to markets in San Francisco. This was a major threat to the species until the trade slacked off by the 1940s.
Large scale wetland drainage projects in the Great Valley destroyed numerous wetlands and lakes and altered rivers in the early 1900s. This reduced and destroyed huge tracks of turtle habitat. As development in California continues, wetlands throughout the state continue to disappear and adds to the decline.
Finally the introduction of three non-native species to many rivers and wetlands inhabited by the Western Pond Turtle has been another cause of their decline. The Red-eared Slider and the Painted Turtle are two invasive turtles that have been very successful at surviving and multiplying over the range of the Western Pond Turtles. They out-compete the pond turtle and take away food and habitat resources. Both produce double the number of young than the Pond turtle. These species are common pets, and were most likely introduced to California wilds by being released by their owners. Since the Western Pond Turtle is the only native freshwater turtle in its historic range, it did not develop the ability to successfully compete for resources with other species of turtles.
The American Bullfrog is another invasive species that has spread throughout the state and is a known predator of Western Pond Turtles. They eat hatchling turtles.
There is an abundance of Wester Pond Turtle on the Gualala River, though they can be hard to spot. They will silently slip into the water when they hear vibrations. The best bet for spotting them is to approach partially submerged basking logs in sunny locations from the riverbank. Or do as we do at the Watershed Council, and slip into the water with a snorkel!