Part 2: surviving and dining in winter

One otter or two above? My otter friends produced an unusual portrait for me one day while they were running around an icy pond. 😊 It looked as if they had brought an extremely long family member with them!

Continued observation showed, of course, that the resident otters (Lontra canadensis) were all of normal stature. During much of the time that I was able to watch them, the temperatures were very low for North Carolina. In our central area of the state, temperatures in January 2025 were the 18th coldest ever recorded, averaging 36.6°F (2.6°C°F). Some days had significantly low temperatures, such as 17°F (-8.3°C) on 23 January.

That weather meant that the local ponds were partly or mostly frozen and had very icy waters indeed. In this and my next blog, I’ll share with you what I observed and learned about how river otters function in such cold conditions.

Their unique metabolism has several features that collectively enable them to survive in extreme cold.

• Their very thick, water-repellent fur covers a dense undercoat that traps air. This fur is 10 times denser than that of the bobcat or red fox, with 585 hairs per square mm.
• The trapped air acts as a buffer against the cold.
• A thin blubber layer underneath their skin provides a second thermal barrier. (It also gives them extra energy when there is limited food availability.)
• Shivering increases their internal body temperature.
• Their high basal metabolism increases when they are actively swimming and diving, which also generates heat and helps them maintain a steady body temperature.
• Their high metabolic rate enables them to pass food through their digestive system in about 60 minutes.

I was sometimes amazed at how quickly they caught one fish after another and now understand how they could process so much food in a short time. Their 36 teeth, including 4 long canines, obviously help them process the food they capture.

The otters also have corporal features that make their food hunting efficient:

• Their ears and eyes are high on their heads, enabling them to swim more easily at the water’s surface.
• They can swim both forwards and backwards, as well as tread water while surveying their surroundings.
• They are near-sighted, which may improve their underwater vision.
• Their whiskers are very sensitive, enabling them to more easily capture prey on dark nights or in murky waters.
• Their ears close under water.
• Their feet have five webbed toes as well as non-retractable claws.
• Their traction on slippery surfaces is increased through heel pads on their hind feet.

The otter family that I observed on several occasions was very adept at catching fish. The NC Wildlife Organization notes that they sometimes collaborate in hunting by herding fish.

The pond otters whom I was watching had certain spots that they kept open in the ice, often diving down and coming up with another fish each time. In this video (click here) you can see one enjoying a meal.

Since I know very little about freshwater fish, I posted a couple photos on a fish identification page to find out just what the otters were eating. Group members debated a bit but then came up with these IDs.

Otters with bluegill sunfish (Lepomis macrochirus)

Otter with a large largemouth bass (Micropterus nigricans)

Biologists say that otters prefer to go after slow-moving fish, including catfish, carp, bass, suckers, and sunfish. Some of the fishing enthusiasts shared about what they had seen otters eat. (Then two men made negative comments and insulted the group moderator, so I removed the photos and left the group so as not to foment more dissension among that group’s adherents.) Here are some of their comments:

• Otters are such cool animals! Have seen a couple groups while fishing/hunting this year in NC!
• They’ll eat most any fish. Where I live they have cleaned out nearly all the fish in the ponds near the river. My old pond was teeming with fish when I owned it and now it holds a fraction of the fish it once did.
• Ours eat a lot of eels. Ophelia/Smith Point, Virginia.
• Here in New Hampshire I saw them eating what appeared to be fallfish last year.
• I used to see otters pull rainbow trout out of the river when I lived in Idaho.
• I hate otter and kill em every chance I get within season…I have had them drag 40 pound catfish out of my ponds and eat them…

It always saddens me when people develop a hatred for an animal (with the possible exceptions of ticks, mosquitoes and chiggers). In any case, I love the otters and will share with you how I saw them play in the next blog.