Muskrats need slow, marshy water most Massachusetts mammals can do without, and Great Meadows National Wildlife Refuge’s Concord River wetlands carry the state’s strongest concentration of records. Walden Pond and the reservoirs threading through Blue Hills Reservation offer the same kind of quiet, vegetated shoreline this animal builds its lodges in.
Reports jump sharply in March and stay high through May, then fall off fast, dropping to a sixth of the spring peak by autumn. That early surge lines up with muskrats becoming more visible as they patch up winter-damaged lodges and start the year’s first litters, not with any change in how many actually live in a marsh.
Full species profile
