Northwestern Pond Turtle
Northwestern Pond Turtle
Other Names: Western Pond Turtle; Northern Pacific Pond Turtle
The Northwestern Pond Turtle is a small-medium sized turtle that reaches a maximum length of 25 cm, although most individuals are smaller than this. They have a smooth, broad carapace that is olive, dark brown, or black, with some light spotting or lines that radiate out from a central point on each . The is pale yellow with irregular dark blotching. The skin is drab grey, sometimes with dull yellow patterning on the neck and chin. Hatchlings are very small (2-3cm), and resemble adults but with a heavily keeled carapace and a large dark blotch in the centre of the plastron.
Listen to the Indigenous words for “turtle” here!
The Northwestern Pond Turtle is similar in size to the Western Painted Turtle and the Red-eared Slider, but can be easily distinguished by its comparatively drab colouration. The Northwestern Pond Turtle does not have yellow stripes on the head, neck, or limbs. Some older Red-eared Slider individuals may also have subtle colouration, but the rear section of the shell is lightly serrated.
Credit: Dave Feliz
Northwestern Pond Turtles
Credit: Leigh Anne Isaac
Western Painted Turtle
Credit: Chris Yarzab
The Northwestern Pond Turtle is considered to be extirpated in Canada, but is still found in the United States west of the Cascade-Sierra crest in Oregon, California, and Baja California in Mexico, with isolated populations reported in Washington and western Nevada. The last report of the Northwestern Pond Turtle in British Columbia was in the 1960s, though it is thought to have had a limited distribution in British Columbia. Biologists are divided on whether Northwestern Pond Turtles were present prior to settlement and have since disappeared, or if they were introduced after settlement.
The Northwestern Pond Turtle hibernates in the winter in mud at the bottoms of ponds and marshes, or in nearby woodlands. They inhabit a variety of aquatic habitats including rivers, streams, lakes, ponds, and wetlands. Deep pools with submerged logs, undercut banks, emergent vegetation, and abundant basking sites are important microhabitat features. Northwestern Pond Turtles also spend a substantial amount of time in surrounding forest habitats. Both males and females spend time on land, but terrestrial habitats are particularly important for nesting females which prefer sandy or gravelly soils along shorelines or other open-canopy habitats with plenty of sun exposure.
Mating occurs in the spring, and females nest shortly after in early summer. Females can lay multiple clutches where they will excavate a cavity in soft soils near water and lay 3-11 eggs in each nest. The sex of hatchlings is dependent on incubation temperature, with warmer temperatures producing more females, and cooler temperatures producing more males. In more northern populations female do not reach sexual maturity until 10-12 years old. The lifespan of Northwestern Pond Turtles in the wild is unknown, but they are likely capable of living over 50 years.
Northwestern Pond Turtles are omnivorous, feeding mostly around sunrise on plants, algae, invertebrates, fish, frogs, snakes, and carrion. Females tend to be more herbivorous, while males are typically more carnivorous. Northwestern Pond Turtles will only swallow their food underwater, as they have difficulty swallowing dry food.
Biological survey records from the 1860s note that Northwestern Pond Turtles were once common in almost every lake and pond in southern British Columbia. Some biologists feel that this species never naturally existed in the province and may have been misidentified in these surveys. Others believe that the report accurately describes Northwestern Pond Turtles, suggesting something has caused the turtles to disappear. In many places in North America, Pond Turtles were common in marketplaces, fetching $3-5 per dozen, leading to overexploitation. Since that time, the species has declined drastically throughout its range. The remaining populations are threatened by continued loss of wetland habitats, disease, and predation of hatchlings by introduced predators like Bullfrogs. It is very likely that over-harvest and urban development in the Lower Mainland has led to the disappearance of this species in British Columbia.
In parts of the United States, Northwestern Pond Turtles are being captive bred for release into the wild to supplement populations. If this strategy proves successful it may be a promising method for reintroduction to British Columbia. Researchers feel that urban aquatic environments may be suitable habitat for reintroduced Northwestern Pond Turtles if managed properly.
Did You Know?
Unlike the Western Painted Turtle, the Northwestern Pond Turtle is very territorial over their basking sites. Large turtles will often be aggressive towards younger, smaller turtles, forcing them to give up prime basking sites, especially when basking sites are limited. Aggressive turtles will open their mouths, showing off the bright pink and yellow inside – a warning that they are about to ram and push each other, or even bite.
Northwestern Pond Turtles seem to be drought tolerant, as they have been reported to estivate (stop eating and reduce their activity) in the mud of any surviving pools of water during particularly hot and dry periods.