"Snakes serve a very important role in the ecosystem," he said. "Snakes are designed to control pest populations and they eat a lot of frogs, turtles [and] fish." Reptiles and amphibians, Lewis added, are "very sensitive to disturbance, and can be used as indicators of environmental change." Snake mortality has become a concern at the Mingo refuge because many are run over by vehicles, whether intentionally or not, during their spring and fall migration periods. The concern has grown to the point officials have begun a study to determine just how snake populations in the refuge are being affected.
Cost-share grant
The U.S. Fish and Wildlife Service, which operates the Mingo refuge, has teamed with the Missouri Department of Conservation, Missouri State University, the Mingo Swamp Friends and others on a challenge cost-share grant to study snake movement and mortality at Mingo. "We're concerned about the number of snakes being run over, and the whole idea behind the study is to minimize mortality," Lewis said. "We want to know, 'Are pregnant females being impacted more than males?'"If they are, he said, that could potentially harm the snake population, because the females produce the young. Lewis also said biologists want to find out what exactly triggers snake migrations.
The western cottonmouth, a venomous species native to the area, was chosen as the test subject "because we knew we had a healthy population," Lewis said. In early April, Lewis and Missouri State University herpetologist Dr. Brian Green captured five males and five females at their hibernaculum, or winter hibernation location, along the rocky bluffs on the refuge's western boundary. After the snakes were transported to a safe location, Green sedated eight of them and surgically implanted a flexible radio transmitter inside their bodies, near their tails. The remaining two were sent to the university later for the procedure. The transmitters will allow officials to use radio telemetry to track the snakes' movements over the course of the next year. Officials also plan to capture and implant transmitters in five cottonmouths during the summer at the adjacent Duck Creek Conservation Area to include in their study.
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