The Recovery of the Northern River Otter

River otters (Lontra canadensis), known for their long torpedo-shaped body, secretive nature and acrobatic and powerful swimming, have been returned to many major water basins in Colorado because of successful reintroduction efforts by Colorado Parks and Wildlife. 

River otters were found throughout Colorado’s waterways in the 1800s. In the early 20^th century, the commercial demand for their pelts as well as poor water quality led to their disappearance from Colorado. The last confirmed River Otter sighting occurred in 1907.

Protecting All Wildlife

In 1973, the state-directed the Division of Wildlife through the Wildlife Commission to begin protecting all nongame as well as threatened or endangered wildlife. This regulatory shift from managing game species only to nongame, threatened and endangered wildlife was a turning point in resource conservation in Colorado. This enormous responsibility led to the protection and management of numerous species throughout the state, including the Canadian lynx, black-footed ferret, boreal toad, cutthroat trout, and lesser prairie chicken to name a few.

By law, the Parks and Wildlife Commission was tasked with managing “species or subspecies of wildlife indigenous to this state which may be found to be endangered within the state should be accorded protection in order to maintain or enhance their numbers to the extent possible.” Following this policy, the River Otter was designated as a state endangered species in 1975 and a plan was put in place to return the native River Otter to the state. 

Reintroduction

Reintroduction occurred from 1976-1991, as a total of 122 river otters were distributed across the Gunnison River, Upper Colorado River, Dolores and San Miguel Rivers, Piedra-San Juan-Navajo-Pine Rivers and their tributaries, as well as the Yampa and Green Rivers.

Today, river otters have been identified in almost every major basin in Colorado – not including the Arkansas – and in 2002 were down-listed from a state endangered to a state threatened species. River otters are not a federally protected species. 

River otters thrive in long, contiguous stretches of rivers and riparian areas with high prey biomass – crayfish, frogs, and fish – good water quality and dense bank cover. 

To survey otters just before high spring runoff flows, CPW biologists float rivers throughout our state looking for signs of river otter including tracks, scat, slides, dens, prey remains, and scent mounds. These elusive creatures are uncommonly seen, yet the rare sighting is memorable.

River Otters on the Rio Grande

Loree Harvey, a Colorado River Watch volunteer, high school teacher, and contract biologist for the Bureau of Land Management (BLM), recounted her first sighting of a river otter on the Rio Grande river gorge in 2016.

“On a routine monthly water sample, myself and one of my former River Watch students and current BLM co-worker, were collecting our sample at State (Lobatos) Bridge, the last bridge that crosses the Rio Grande before the river flows into New Mexico,” she said. “The ice on the river was thick and extensive, but there were a few open holes where water could be obtained.  As we approached an opening in the ice, we noticed a lot of reddish urine stains in the snow, tarry-looking scat, plus some fresh, smoothed-out drag marks in the vicinity. Looking at the scat more closely, it was packed with crayfish and macroinvertebrate parts, and my first musings of ‘coyote?’ and ‘raccoon?’ were morphing into maybe, just maybe…river otter?

“Rumors of river otters on the Rio Grande had been surfacing in recent years, but no one had produced conclusive evidence. The excitement of this possibility caused us to pause on water collection, and we both withdrew from the opening and silently waited several feet away. It was a long shot that we would actually see an animal appear out of that hole in the ice, but not more than five minutes after becoming silent and standing still, the whiskery face of a river otter popped out of the hole, and the animal hauled itself out onto the ice.”

To the delight of Harvey, the otter remained unaware of their presence and began rolling around on the crusty surface, grooming and drying off by basking in the sun.  

“He didn’t see or smell us, and we stood stock still and just lived in that moment, enjoying the graceful movements of this amazing animal,” she said. “After a time, it slid back into the water, and Tayler and I quietly gushed about the incredible scene we had just witnessed.”

Have you seen a river otter?

Please report any river otters sighting on the Colorado Parks and Wildlife website.

Colorado Parks and Wildlife is Celebrating its 125th Anniversary
Colorado Parks and Wildlife is celebrating its 125th Anniversary to honor the legacy of our agency and the talented staff who make fulfilling CPW’s important mission possible. For more stories like this, please visit the Colorado Parks and Wildlife’s 125th Anniversary web page!

Story contributions by Loree Harvey (Monte Vista High School Teacher; CPW River Watch Volunteer 2009-Present), Eric Odell (Species Conservation Program Manager 2006-Present), Megan McConville (Water Quality Specialist; River Watch Program Manager 2019-Present)