A caller recently asked about animals she had seen swimming in Sonoma Creek. She lives on the creek and had seen several animals that appeared to be mammals, looked like and seemed playful like seals, though she was quite certain that seals wouldn't be found in the middle of the valley.

Once in a while I find that I have learned something for my years of exploration here. What was clear to me was that the caller was seeing river otter.

Last fall I was visiting one of our creek restoration project sites in the early afternoon and I had the chance to see river otter in action. In a large pond upstream from the site, a head abruptly emerged from around a bend and swam toward me. Full of energy, it rolled through the water almost like a long reptile, undulating over and under the surface. Within a few seconds, another and another head joined the first. I watched in casual amazement, attempting to appear unsurprised to the biologist who had joined me on this visit. Though I had seen an otter while kayaking, it wasn't until there were a full five at play, rising, even leaping up out of the water right in front of me that I knew these were otter.

Otter belong to the family mustelkidea which also includes the weasel, skunk, mink and marten. Our otter are Canadian Otter (Lutra canedensis), a species of river otter which are distributed widely in the US, though Sonoma Valley is at the southern limit of their range. I expect this is mostly due to lack of available water and food further south. River otter are different from sea otter. Sea otter will not be found outside of the ocean conditions they are distinctly suited for, especially kelp, and river otters are adapted to and clearly prefer fresh water habitat and food. River otter eat fish, frogs and even small birds and rodents and will fish several miles of creek or can travel even further overland each day in search of food.

Otters have an interesting life cycle and perhaps even more interesting behavior. Life for an otter begins in a hollowed out log or stream bank, or a borrowed den of some other animal. The male leaves just before the young are born in April or May, and the female spends the next eight months caring for them. The male usually returns though, after the young otters are about half grown. Like many mammals, the young are born blind, but not so typically, they are born with a full fur coat. Developing slowly, at about ten to twelve weeks the one to four young will venture outside and the mother will teach them to swim and to hunt. At about four months the young are weaned and soon after the male returns to help raise them. Otter can live fifteen years and larger males can weigh up to twenty five pounds.

Otters are great swimmers, and not very shy about this fact. With a long tapered tail, webbed toes, and ears and nostrils that are valved, an otter can move very rapidly through the water and can hold its breath for several minutes. Otter skin is sleek and appears almost black, especially in dim light. It is not surprising that at first glance a river otter in the water might be mistaken for a seal. Their most famous behavior, one I had the opportunity to witness first hand, is their playfulness. In most texts that describe the river otter, there are colorful descriptions of river otter "slides," places where the otters wear a furrow in a stream bank or snow bank up to a foot or more wide and many feet long. Not only will an otter slide in this track, but will push off along the way to gain speed. They also play tag, wrestle and "roll in the grass," literally, sometimes leaving a musk scent mark in the twisted grass.

As they are not terribly shy, it is quite possible that with a little patience and some luck you too will see river otter in Sonoma Creek someday. Though you may have to wait somewhat longer to see a seal there.