The Napa River and its attendant waterways sound out their songs all year long. Within the folds of each waterbody, the landscape is host to ecological areas containing a wide diversity of life. Included in the lengthy list of flora and fauna is the North American river otter.
I joined a Zoom webinar presented by Megan Isadore, director and co-founder of the River Otter Ecology Project, who explained, “The mission of River Otter Ecology Project (ROEP) is to engage the public in supporting conservation and restoration by linking river otter recovery to the health of our watersheds through education, research, and community science.”
During the webinar, I discovered that the river otters now thriving in and amongst Napa County’s three watersheds are only one of 13 otter species in the world. The otters here are considered to be one of the largest members of the Mustelidae family which includes skunks, badgers, minks and more.
River otters, which may live up to 15 years in the wild, nearly disappeared from the Bay Area due to trapping, hunting and water pollution originating from diminished wetland habitats and increasing land development. Trappers loved their dense fur which was designed by nature to insulate otters from cold conditions on land and water.
When the Clean Water Act was enacted in 1972 and the lands were managed proactively, river otters began making a comeback. Today river otters are the only otter species not on the threatened species list.
Other otter species suffer from air and water pollution as well as trafficking. River otters are semi-aquatic, meaning they can thrive both on land and water.
Since they are carnivores, they feast upon amphibians, fish, grebes, gulls, coots and shellfish. They are voracious eaters since hunting in cold water consumes a high amount of calories. River otters munch on fish in both ocean or freshwaters.
Otters, found in North America and Canada, grow to 3-4 feet in length and weigh in at up to 25 pounds. Their cousins, the sea otters who live in seawater, can weigh up to 65 pounds.
Another difference between the two species is that sea otters sleep in seawater while river otters snooze on land, preferably that with grasses or other vegetation in which to take refuge; or they may sleep in an underground hideaway.
According to Megan Isadore, data collected from the River Otter Ecology Project from 2012 to present times has shown 300-600 otter sightings per year, many of which originate in Napa County. Unfortunately, many otters are killed or injured by cars as they attempt to cross the road from one waterway to another. All otters studied had rodenticide in their systems.
What happens to Napa’s river otters during the cold months of winter? Isadore said, “River otters are well-adapted to cold; their range goes as far north as Alaska. Their thick fur acts almost as a dry suit, keeping them warm while they hunt for food in the water. Life is more difficult for otters residing in very snowy and icy places, but they manage. Here in the Bay Area, they have no worries at all about cold; they are out hunting and swimming all of the time.”
Conversely, in the dry summer months when some of the creeks and wetlands dry up, Napa’s river otters travel to better habitats, where they pursue other rivers, creeks or lakes. This provides them with freshwater opportunities replete with ready supplies of prey and allows them the use of the clean water to groom themselves and quaff their thirst.
Often, they are moving from one natal den to another where they raise their pups. Of course, all of this moving around to improve habitat choice increases the chance of being hit by a car. Some areas, like San Jose are working to prevent otter mortality by installing culverts for ease of travel. This ‘habitat connectivity’ around water sources is vital for the survival of their young.
That’s where the Otter Spotter citizen science program comes in handy. Reports from the public inform scientists and wildlife groups as to where otters thrive, as well as where they may be in peril. Due to the public’s involvement, the River Otter Ecology Project has reviewed thousands of otter sightings which has allowed them to change the river otter range map for California.
Otter Spotters submit photos from their phones by sending the photos to riverotterecology.org and clicking on their Otter Spotter icon. The website is laden with interesting videos of these charismatic critters like the one where a river otter scares a bald eagle at Jenner and otters in Abbott’s Lagoon at Pt. Reyes Seashore have their cache of coots eaten by coyotes.
The River Otter Ecology Project’s Otter Spotter citizen science program invites the public to report otter sightings so that otters may be mapped for both the public, and to assist agencies like the California Department of Fish and Wildlife, state and national parks along with wildlife groups.
Who knows? You may decide to become an Otter Spotter who enjoys nature while contributing to science.
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