Observing Seals in Monomoy National Wildlife Refuge

seal swimming monomoy island cape cod Monomoy National Wildlife Refuge encompasses more than 7,000 acres of sand dunes, salt marshes, and sandy beaches in Chatham. Every year, tens of thousands of seals visit the refuge to find mates and have pups. During mating season, you can find these seals sunbathing on the beaches of Monomoy Point and, especially, on the sandbars of South Monomoy Island.

Two seal species, the harbor seal and the gray seal, live in the water around Cape Cod. From a distance, it’s often difficult to distinguish these two species from each other, but there are some significant physical differences between them.

Harbor seal Gray seal
  • Up to six feet in length
  • Weigh up to 245 pounds
  • Close-set nostrils that form a “V”
  • Gray body with uniform spots
  • Up to ten feet in length
  • Weigh upwards of 750 pounds
  • Wide-set nostrils that form a “W”
  • Gray body with a white belly and random spots

For these seals, the mating season lasts from September to March eachmonomy islands year. In September and October, a very large number of seals “haul out” at Monomoy National Wildlife Refuge. As many as 50,000 seals visit the Cape at this time, with most of them heading for the secluded beaches of Monomoy Point and the sandbars of Monomoy Island. While a large seal population is good news for seal watchers, it also strains local fish populations and attracts sharks.

There are several ways to view the massive seal haulouts in and around Monomoy National Wildlife Refuge:

  • You can view the seal haulouts on the sand bar along the left side of the harbor inlet from Chatham Light (37 Main Street) at low tide. Just make sure you bring binoculars!
  • You can usually see seals from the observation deck at Chatham Fish Pier (45 Barcliff Avenue).
  • On the Monomoy Nature Trail, you can get closest to the seals hauling out on the refuge’s many beaches.
  • A private boat or a chartered boat tour will take you to the massive seal haulouts on North and South Monomoy Island. The Monomoy Island Ferry operates between the islands and the refuge headquarters from May to October.

Keep in mind that the Marine Mammal Protection Act protects seals from human harassment. To comply with the law, avoid doing anything that provokes a reaction from the seals when you see them, since anything that alters the natural behavior of the seals is technically harassment. To stay on the safe side, Monomoy National Wildlife Refuge recommends remaining at least 150 feet away from the seals at all times.

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