River otters are identified as a furbearer species and are the largest member of the weasel family (Mustelid) in the northeastern United States. Adult otters weigh between 11 and 30 pounds and are roughly 3 to 4 feet long.
They have long slender bodies with short legs and webbed toes. Their thick tails and dark brown water-repellent coat enable them to be excellent swimmers and to catch their meals. Otters are carnivores and primarily eat fish, but will also eat snakes, turtles, frogs, crayfish, birds, and small mammals.
Every year, river otters birth one litter with an average litter size being 2-3 babies. Baby otters, also referred to as kits, are born blind and toothless. When they reach three months of age, they leave the den, can hunt, and are completely independent at 6 months old. At 7 to 8 months old, the kits leave their den and are ready to explore Massachusetts.
Instead of building their own homes, river otters live in abandoned beaver lodges, other burrows, and tall grass. Adults typically live alone or with one other otter. They often socialize in groups and utilize a variety of sounds, such as chirps and grunts, to communicate with one another.
River Otters in Massachusetts
By the 1970s, the otter population had significantly decreased, and they were even extinct in a few states due to overharvesting their fur. Since then, pollution control, wetland conservation, the increasing beaver population, and reintroduction programs have drastically increased the population. Today, river otters are found throughout Massachusetts in rivers, lakes, and coastal habitats. They remain active year-round and can be best spotted at dawn or dusk because they are primarily nocturnal. Otters can be seen playing and sliding down snowy or mud-covered hills when they are not in their aquatic habitats.
Otters have very few predators and are most vulnerable to being caught by animals and humans when they are on land. Since otters are a furbearer species, residents are allowed to trap otters for their fur from November 1st to December 15th. These devices to catch otters can catch any animal, wild or domestic, who walks or swims into them, causing intense suffering and death. The MSPCA opposes legislation that would expand trapping in Massachusetts.
Possible Conflicts
There are very few negative interactions with River Otters. However, they may take advantage of ponds with a high population of fish, such as stocked backyard ponds and hatcheries. Additionally, they may den under houses and structures near water. If you are experiencing any issues with otters, contact MassWildlife.
Fun Facts:
- They have delayed implantation where they hold onto the fertilized egg for 10 to 11 months after breeding
- They can hold their breath for up to eight minutes
- An otter’s tail represents 30-40% of their total length
Sources and More Information
MassWildlife – Learn About River Otters
MassAudubon – Blue Hills Trailside Museum
MassAudubon – River Otters
In the Headlines
New Bedford Guide, Winter brings many opportunities to spot Massachusetts’ otters, January 2, 2022.
How To Coexist With Falmouth’s Otters. The Enterprise Falmouth. Geist, G. April 5, 2024.
