April 2026 Newsletter

From the Contact Station Bonus!

Otterly Delightful

Image of River Otter along slough bank by Charlie Rutkowski

River Otters are ever the opportunists when it comes to lunch. Mostly, they like fish; slow movers of the 4-to-6-inch variety like this carp in the mouth of this lucky otter. We have had reports of otters viciously going after small ducks in the canal along the road to the hunt gate. Not a pretty sight; there was no hope for the duck in the video I saw. They will also consume crabs, mussels, crayfish, amphibians, injured or molting ducks or geese, eggs from birds and fish, and small mammals. Interestingly, they digest and metabolize food very quickly, and it passes through their intestines within an hour! Otters can smell concentrations of fish and will follow a scent trail to an upstream pond to feed. 

Otters have dens for extreme weather shelter and birthing. They line them with small sticks and shredded vegetation. They might be in log jams, hollow logs or abandoned lodges and bank dens made by nutria or beaver. On our refuge, they have used some old beaver tunnels along Campbell Slough in the closed section of the refuge. That is not surprising as they are rather wary critters and would look for a more remote area than the human-busy River S for denning.  Entries are well hidden, often far enough below the water surface to prevent them from being seen.

River Otter family by Charlie Rutkowski

River otters are active year-round and are constantly on the move. No wonder we have so much trouble re-finding them. They have a regular circuit which they cover in one to four weeks. Males can travel 150 miles within a particular watershed and its tributaries in a year. A family may range 10 to 25 miles in a season. Females with young in a den will not be so mobile, but a family can still range 10 to 25 miles in a season. They are active day and night but tend to be more nocturnal when closer to areas with people.

River Otter postprandial snooze by Susan Setterberg

Because otters have delayed implantation, their gestation ranges from 285 to 375 days. After breeding, the fertilized egg does not immediately attach to the uterine wall. Two to four pups are born sometime between March and May. The pups begin playing at four weeks old and learn to swim around seven weeks old. By eight to ten weeks, they are exploring beyond their den and eating solid food. The basic social group for otters is a female and her offspring. Males, other than during breeding times, usually lead solitary lives. An adult male averages 4 feet in length with the tail and weighs 20 to 28 pounds. The females are smaller. Pups leave their family structure in late fall and wander to establish their own territories.

Besides feeding, they spend a lot of time in group play. Along the banks of our sloughs, they will mark their territory by scratching, rubbing, and rolling on the ground. Drying their fur and grooming also consumes some of their time. Then there is the occasional nap.

Time to move on; if the winds be fair: It is that time of year, and we have been seeing the movement of waterfowl and cranes as they turn north toward their summer breeding grounds. In mid-March, while a volunteer group was gathered on Bachelor Island to do our twice-monthly goose count, Biologist Alex was remarking that he had been watching swans, geese, and cranes moving north most of the morning. We were wondering if anything would be left to count. We heard both Trumpeter and Tundra. Alex also remarked that the forecast said there would be a change in wind direction out of the north during the day. I had noted the temperature when I arrived at 50 degrees. During our conversation, we started seeing swans coming south low over our heads. In a short period of time, the temperature had dropped to 45 degrees, and everyone outside was zipping up their jackets. A couple of hours later, while doing the goose count on River S, it was clear the swans had thought better of leaving the area, had circled back, and were resting and eating in very large numbers in Ruddy Lake and Rest Lake. Interesting to experience nature in action firsthand.



Finally: Knowing that we are seeing the migration of Sandhill Cranes moving north, here is an interesting triptych by Charlie Rutkowski of sequential images of a crane preparing to take off and finding air. Question: How many pairs will stay this year to nest? Can we hope for three again?

Sandhill Crane triptych by Charlie Rutkowski



-Susan Setterberg, Ridgefield National Wildlife Refuge Contact Station Volunteer