Philadelphia County, which is simply the city itself, logs more muskrat records than any other in Pennsylvania: 100 of the state’s 732. Allegheny County, around Pittsburgh, comes next with 84. Muskrats do well in urban creeks, tidal river edges, and park ponds, but a ranking led by the two biggest cities mostly shows where the cameras are. Every one of those 732 records comes from iNaturalist.
Beyond the cities, the named places lean northwest. Moraine State Park, built around a reservoir in Butler County, has the most, ahead of Presque Isle State Park, a sand peninsula curling into Lake Erie with marshy ponds behind its beaches. Pymatuning State Park on the Ohio line also appears, and Erie, Butler, and Venango counties all make the top dozen. Centre and Cumberland counties hold the next-largest totals after the two cities, valleys of farm streams and limestone springs in the middle of the state, and Big Spring Creek turns up as a named site there.
Records jump in March and peak in April at 154, then taper through summer and stay low from September through January, with December the quietest month. NatureServe ranks the muskrat S4, apparently secure, in Pennsylvania, one step below the top tier, and it’s native across the state.
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