Something is happening to the muskrats of Pennsylvania, and the rest of the northeastern U.S. The species has been in a downward spiral since the mid-1990s.
And biologists with wildlife agencies throughout the region aren't certain about what's happening to the small, aquatic rodents.
"It's a real puzzle in the Northeast," said
Matthew Lovallo, furbearer biologist with the Pennsylvania
Game Commission, who just returned from regional meetings
among biologists.
"It's the No. 1 concern among furbearer managers in the Northeast right now."
Harvest numbers are the most reliable measure of population trends, and, in Pennsylvania, those have dropped from about a half-million annually to just 120,000 last year.
In some areas, like Prince Edward Island, recruitment of new generations of muskrats into the population, which in good times could involve as many as four litters per year, has dropped by as much as 50 percent.
"There are lots of theories out there [about the reason for the decline] and I can't really point to one as better than another," Lovallo said.
Among the theories is the possibility that the cleaner water resulting from the Conservation Reserve Enhancement Program, which takes marginal farmland out of production and into preservation, is just too clean for the muskrats.
That cleaner water may be providing less vegetative growth of the type that muskrats eat. Invasive plant species could be contributing to the problem.
Biologists in Pennsylvania hope to explore that theory in upcoming research projects that will gather information from field research and from trappers.
