Based on 1,264 research-grade iNaturalist observations in Massachusetts, Grey Seal is most often recorded in August; in Massachusetts it behaves like a summer visitor / breeder. It ranks #12 among mammals recorded in the state in our data.
Halichoerus grypus
Grey Seal in Massachusetts by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also seen in Massachusetts in August
Eastern Cottontail
White-tailed Deer
Eastern Gray Squirrel
Eastern Chipmunk
Humpback Whale
Common Raccoon
Groundhog
Coyote
Places to look in Massachusetts
Botanical GardenArnold Arboretum
Botanical GardenBoston Public Garden
Botanical GardenBerkshire Botanical Garden
State ParkHalibut Point State Park
State ParkHammond Pond Reservation
State ParkTolland State Forest
FAQ
When does Grey Seal appear in Massachusetts?
Mainly June–November, with the most records in August.
How common is Grey Seal in Massachusetts?
It ranks #12 by number of iNaturalist observations among mammals in Massachusetts (1,264 records in our sample).