Western pond turtles
-Actinemys marmorata
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| Western Pond Turtle at Pierce Lake |
Western pond turtles have nearly disappeared from Washington,
largely due to predation by nonnative bullfrogs (Rana catesbeiana). Working collaboratively with Seattle's Woodland
Park Zoo, Washington Department of Fish and Wildlife (WDFW)
the U.S. Fish and Wildlife Servicea (USFWS), and the Oregon Zoo "head-starts" newly hatched turtles gathered from wild sites.
The turtles are nurtured at both zoos for about 10 months until they grow large enough to avoid being eaten by the non-native bullfrogs and large mouth bass.
Turtles have a naturally slow rate of development, female pond turtles take 10 or more years to reach reproductive age. Continued disturbance along with their slow development rate has made it so that very few hatchlings make it to adulthood.
Western Pond Turtles use both land and water. This species uses the terrestrial habitat for nesting, over wintering, basking, and even during the hottest part of the summer turtles will retreat to land. Pond turtles use the aquatic habitat for feeding, breeding, and sometimes basking. Due to their extensive use of both land and water environments these turtles are especially susceptible to habitat degradation. Alteration of waterways, including damming and water diversion, and draining of wetlands for development, and roadways have drastically altered and decimated much of the Western Pond Turtles habitat. All of the alterations to habitat have resulted in populations of Western pond turtles being concentrated into a few locations. These turtles were already in trouble due to habitat degradation and disease, but bullfrogs are still their biggest threat. This non-native frog now thrives throughout the west, driving pond turtles and a host of other small, vulnerable aquatic species to the brink of extinction.
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| Non-native bullfrog at Pierce Lake |
Each year, since the head-starting project was launched in 1990, recovery workers take to the field under the supervision of pond turtle expert Kate Slavens with the Washington Department of Fish and Wildlife to count, trap, mark and fit transmitters on adult female Western pond turtles. The female turtles are monitored every two hours during the nesting season (between June-July) in order to identify nest sites. These vase shaped nests are dug by the female in dry densely packed soil. The female urinates on the soil to soften dirt. The female deposits 2-11 eggs and then covers the nest with mud (a mix of dirt and urine) and vegetation. Once the female completes the lestand leaves the area, researchers protect the nest with a wire "exclosure" (a cage that help prevent predators from eating the eggs.) The eggs are allowed to incubate naturally; the researchers return in the fall and collect the hatchlings which are about the size of a quarter when hatchlings are taken to the zoo facilities. The zoo provides a safe environment, free from predators with ample lights and food to help turtles grow for a longer time than they would in the wild. The lighting and warm temperatures tricks the hatchlings into thinking its summer so they continue to eat and grow, rather then becoming dormant like they would in the wild during this period. After about 10 months, when the juvenile turtles have grown large enough to avoid being eaten by most predators, they are returned to the wild in areas designated by the Western Pond Turtle Recovery Plan.
The Western Pond Turtle Recovery Plan requires that at least 5 populations be established in both the Puget Sound and Colombia River Gorge areas. With each population consisting of at least 200 pond turtles with no more than 70% adults, in an area that is protected from development and free of major disturbances. Suitable habitat will allow for natural recruitment of juveniles into the population, creating a self sustaining population. The establishment of these 5 populations will allow the Western Pond Turtle to be downlisted from Endangered to Threatened in the state of Washington.
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| Hatching turtle |
The newest releases in July of 2008, bring the total number of head-started turtles to around 1400! Scientists tracking the released turtles estimate that 95 percent of the turtles released back to sites in the Columbia Gorge have survived. Some of the juvenile turtles are equipped with radio transmitters before release so biologists can track juveniles and learn more about post-release dispersal (how they spread out in the environment,) habitat use, during both the active and hibernation periods, and, ultimately, their survival rate.
The pond turtle, which can live up to 70 years in the wild, takes about 10 years to reach sexual maturity. The 1st head-started turtles released in 1991 in the Columbia Gorge are now reproducing and laying eggs in the wild! In the past few years, this cooperative effort has brought the pond turtles' numbers in Washington up from a low of 150 in 1990 to nearly roughly 1,400 today. Currently listed as an Endangered Species in Washington and a Sensitive Species in Oregon, the Western pond turtle was once common from Baja California to Puget Sound. With efforts put forth by the Washington Department of Fish and Wildlife to improve habitat and control non-native predators, in collaboration with head-starting at the Woodland Park Zoo in Seattle, the Oregon Zoo, and starting in 2008 the Oakland and San Francisco Zoos in California, hopefully the Western pond turtle will again be a common sight throughout its original range.
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| Pierce Lake |
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Turtle Release |
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