Western pond turtles raised at the Oregon Zoo were released into the Columbia River Gorge earlier this week. This is an encouraging benchmark along the way toward saving an endangered turtle species that in the not-too-distant past was teetering on the brink of extinction.
The Zoo has been reintroducing these endangered turtles throughout the summer, and this batch of nine was the last one for the year. Why does the population of these endangered turtles need to be supplemented with young turtles that have been head-started at the Zoo? While the turtles face numerous threats including habitat degradation and disease, the primary threat they face is the American bullfrog. This non-native/alien predator has devastated populations of the turtles and other small wildlife species in the west. As the Colorado Division of Wildlife restocked trout streams in the early 1900s, the bullfrogs invaded fish hatcheries and their larvae were accidently included with the fish stocks used for re-stocking. Young turtle hatchlings make for easy prey until they reach a certain size – about two ounces – when the bullfrogs can’t consume them. The head-starting program allows the turtles to grow year around and when they reach the target weight and the bullfrogs are no longer a threat, the turtles are released.
This year marks the 20th anniversary of the Western Pond Turtle Recovery Plan, started by the Woodland Park Zoo and Washington Department of Fish and Wildlife in 1991. The Oregon Zoo has been a collaborator since 2000. Twenty years ago, there were as few as 150 turtles left in the Columbia River Gorge – today, that number is more than 1,500.
Listed as an endangered species in Washington and a sensitive species in Oregon, the western pond turtle was once common from Baja California to the Puget Sound. To learn more about the western pond turtle, visit http://www.oregonzoo.org/Conservation/westernpondturtle.htm.
This is one example of a program that is helping an endangered species, suffering from the introduction of a non-native invasive species. Whether it is the snakehead fish (native of China) invading tributaries of the Chesapeake Bay or the giant salvinia plant (a native of Brazil) colonizing lakes in Texas, invasive species pose a growing threat to native species and ecosystems around the world. It’s good to hear about an ongoing success story that is saving a small species that might go unnoticed by many.