GOLDS: Turtles lost and found in B.C. wetlands
Wetlands are one of my favourite places to enjoy nature. Sadly, at least 75% of the wetlands that once existed in the lower Fraser Valley have disappeared. Their demise has been mainly due to drainage for agriculture and development. Although we have belatedly developed a keen appreciation for salmon streams, wetlands continue to be viewed by most people as more of a nuisance than sites of high habitat value.
It should come as no surprise, then, that some of the species most at risk in B.C. are ones that rely on wetlands. One of these is the western pond turtle, last seen in B.C. in 1959. Now officially extirpated from B.C., it is still found in the U.S.A. Once this pond turtle shared some of its habitat in B.C. with the endangered western painted turtle, a species, I was delighted to recently learn, that is still found locally in small numbers.
If you enjoy walking in places such as DeBoville Slough, Colony Farm or Burnaby Lake during spring and summer, you may have glimpsed one or two of these turtles basking on floating logs in the sunshine. Females, which are larger than males, can reach almost dinner-plate size.
They derive their name from the bright red and yellow markings on their lower plate, called a plastron. These markings can be hard to see when turtles are observed in a natural setting.
There are actually three subspecies of painted turtles in Canada. It is only the western subspecies found on the south coast of B.C. and the inner coast of Vancouver Island that is considered to be endangered. In B.C.’s Interior, a different subspecies is slightly less at risk but remains a species of special concern.
Painted turtles emerge from hibernation sites in the muddy bottoms of ponds in spring and start to bask on logs in wetlands once water temperatures reach about 10 C. Mating occurs underwater and nesting can begin in late May or June.
To lay their eggs, females leave the water at dusk and laboriously move up to 150 m across land in search of suitable nesting sites, which typically have bare, loose soil. There, they dig a nest and lay eggs, which hatch in late summer or early fall. The hatchlings stay within the nest to over-winter and, if they survive the cold temperatures of winter, they emerge the next spring and move to wetlands, where they feed and grow.
Young turtles are carnivorous and will eat tadpoles and aquatic insects. As they grow older, they shift to a vegetarian diet.
Female turtles lay their first eggs at about 12 to 15 years of age. Females are typically larger than males and need to bask in the sun to gain the energy they need for egg-laying.
The only other turtles with which western painted turtles might be confused are the red-eared sliders, which are naturally found only in the southeastern U.S.A. but were once sold across the continent as “dime-store turtles.” Some turtle owners abandoned their pets by releasing them into wetlands, where some have persisted.
Mild weather in this part of B.C. allows the adult red-eared sliders to survive but our winters are believed to be too cold to permit the survival of their hatchlings. Since both painted turtles and red-eared sliders can live for 30 to 50 years or more, the red-eared sliders sometimes seen in local wetlands are probably aging survivors released many years ago. As they get very old, some sliders lose the characteristic red mark on the side of their neck. Thus, when viewing turtles from a distance, it is difficult to discern if they are red-eared sliders or western painted turtles.
Recently, biologists, working as part of the South Coast Western Painted Turtle Recovery Project, funded by the federal government and other partners, have been conducting turtle surveys in the Tri-Cities. The biologists are pleased to report several sites — including DeBoville Slough, Como Lake, Lost Lake, Colony Farm Regional Park, Lafarge Lake and Minnekhada Regional Park — currently support a few western painted turtles.
These turtles were also formerly identified at Burnaby Lake Regional Park, where a successful nesting program, monitored with the help of volunteers, has been in place for a couple of years. The Friends of DeBoville Slough, Burke Mountain Naturalists and the city of Coquitlam are currently investigating the possibility of creating suitable nesting sites and improving basking habitat at DeBoville Slough. Nest sites must be chosen carefully and are vulnerable to predation by animals such as raccoons, otters, dogs and coyotes.
Now that we know we have endangered turtles inhabiting several of our wetlands, people need to be careful to not disturb them. Dogs should be kept leashed in such areas, out of wetlands and not allowed to dig in potential turtle nesting sites.
• More information is available at here. The Western Painted Turtle Recovery Team can be contacted by emailing firstname.lastname@example.org.
Elaine Golds is a Port Moody environmentalist who is vice-president of Burke Mountain Naturalists, chair of the Colony Farm Park Association and past president of the PoMo Ecological Society.