Summer survey finds river otters continue to thrive on the Yampa River after successful reintroduction |

Summer survey finds river otters continue to thrive on the Yampa River after successful reintroduction

Scott Franz
Colorado Parks and Wildlife biologists and volunteers float the Yampa River in Dinosaur National Monument in July during a count of the river otter population there. The survey found evidence of otters in every 5 kilometer search area from Deerlodge Park to Echo Park, suggesting the population is in good shape after successful reintroductions.
Courtesy Photo

— The early 1900s weren’t a good time to be a river otter in the state of Colorado.

In 1906, the last known otter in the state was trapped on the lower Yampa River, and the species was declared extinct here.

Today, the state’s wildlife biologists are confirming it’s a whole different story.

A recent summer count of the river otter population on the Yampa River where it runs wild through the canyons in Dinosaur National Monument suggests the species is thriving in Northwest Colorado a little more than a decade after a reintroduction effort nearby in Utah.

Between 1989 and 1992, 67 river otters, mostly from Alaska, were released in the Green River in Utah.

The otters that can be seen today in the Yampa in this part of the state are descendants of these otters that made it all the way to Lake Catamount.

Otters also have been reintroduced in other parts of the state, including in Rocky Mountain National Park.

Thanks to the successful reintroductions, there are self-sustaining populations across the state today, and the otter’s state listing soon could be downgraded from “threatened” to a “species of concern.”

“It’s a really neat recovery story,” local Colorado Parks and Wildlife biologist Liza Rossi said Wednesday. “It’s a species that was completely extirpated from the state, and now we have them through many of Colorado’s Western Slope rivers.”

Before the otter’s listing can be downgraded and lead to things like the possibility of trapping the species in the future, the state’s wildlife agency needs to confirm the otter population sufficiently has recovered.

For five days in July, Rossi and a team of nine wildlife biologists and volunteers geared up and floated a long section of the Yampa through Dinosaur National Monument to do just that.

What they found was encouraging.

Rossi said in every 5-kilometer stretch of search area from Deerlodge Park to Echo Park deep in the heart of the Monument, the biologists found evidence that a river otter had been there.

Although the animals can be elusive and never actually were spotted by any of the biologists, the otters aren’t very good at covering their tracks.

For one, they leave a very distinguished slide mark where they slip into the river on their bellies.

“It looks like a track left by a tube or a sled,” Rossi said.

Their scat also is fishy and distinctive.

When they weren’t floating the river on rafts and duckies, the biologists took turns hiking along the riverbank searching for the evidence of otters.

When evidence was found, they’d document it and move on to the next 5-kilometer stretch.

“As far as we can tell, it does seem the reintroductions have been successful, and we do have self-sustaining populations based on our surveys,” Rossi said. “They do seem to be spreading and doing pretty well.”

To reach Scott Franz, call 970-871-4210, email or follow him on Twitter @ScottFranz10

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