Muskrat populations declined sharply across North America over the last 50 years or so, and wildlife scientists have struggled to understand why. A Pennsylvania research team investigated whether pathogens, parasites, environmental contaminants and disease may be contributing to this decline.
Trappers saw steep declines in muskrat harvest throughout the animal’s native range, with decreases exceeding 50% in some states, according to David Walter, Penn State adjunct assistant professor of wildlife ecology in the College of Agricultural Sciences. In Pennsylvania, for example, according to the state Game Commission, the muskrat harvest declined from 720,000 in 1983 to 58,295 in 2010.
“Some of that decline can be attributed to a reduction in trapping activity, but clearly the muskrat population is significantly smaller than it used to be,” he said. “A number of theories to explain the widespread muskrat declines have been proposed, including habitat loss, predation, environmental contamination and diseases. In this study, we examine a number of those possibilities.”
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