Looking for the Lost River Otters of the Southwest

No one has seen a Southwestern river otter in the wild for more than three decades, but Paul Polechla refuses to give up on this animal

  • Paul Tolme
  • Jun 01, 2003

THE SETTING SUN blazes orange on the hills of southern Colorado’s high desert as Paul Polechla sloshes along the banks of the San Juan River. The biologist has spent more than 12 hours crossing wide mud flats, whacking through willow thickets and wading tricky currents to search for tracks and scat. He has found the prints of coyotes, mule deer, wild horses, raccoons and beavers—but he is not searching for these creatures. He is looking for the lost river otters of the desert Southwest.

Some believe that trappers eradicated the Southwestern river otter during the last century. There have been no confirmed sightings of this river otter subspecies in more than 30 years. But Polechla (poe-LECK-la) refuses to consign Lontra canadensis sonora, which once ruled the region’s roaring waterways, to the dustbin of extinction.

"The million-dollar question is this," Polechla says after darkness ends his search for the day. "Are there any surviving pockets of Southwestern river otters out there? I believe there could be. We still have a lot of wild country in the Southwest."

For inspiration, Polechla need look no farther than a display case beside his desk at the University of New Mexico’s Museum of Southwestern Biology. There, stuffed and mounted, is one of only three known specimens of the Southwestern, or Sonoran, river otter. A state wildlife officer caught this one—whose skeleton is in the Smithsonian—on the Gila River in 1953. It is the last documented Southwestern river otter caught in New Mexico.

That’s not to say there are no otters in the Southwest. Beginning in the 1970s, various states in the region began releasing otters trapped in other parts of the country, and some of these reintroduced otters have established local populations. This makes the search for native otters more complex, for it would be nearly impossible to differentiate these newcomers from original Sonoran otters by their tracks or even on sight. Even more confounding is the possibility that reintroduced otters could have mated with any remaining indigenous otters, diluting the original genetic line. All of this has caused Polechla to urge a moratorium on any more otter relocations in the Southwest, including one being considered for the Grand Canyon, until all the region’s rivers are surveyed.

"Southwestern river otters represent genetic diversity, and that diversity should be preserved at all costs," says Polechla. "It’s a make-it-or-break-it situation for these guys, and we ought to proceed carefully."

Photo: © ART WOLFE

OTTER KIND: The Southwestern, or Sonoran, is one of seven North American river otter subspecies. Other subspecies are common in many places, such as the Skagit River in Washington, where these animals peer out from a log.

Southwestern otters were among the largest of the seven generally recognized subspecies of North American river otters, Lontra canadensis. The species once thrived in lakes, rivers and marshes across the continent. While estimates on its numbers before the arrival of Europeans are difficult to come by, the river otter probably inhabited every river drainage from Maine to California.

River otters weigh about 20 pounds and can measure four feet in length including their long tails, which are used for steering and propulsion. Unlike their cousins the sea otters, which spend most of their time in water, river otters spend half their time on land and use rivers to hunt and travel. On land, otters are clumsy, but in the water they move with the grace of dancers. Long whiskers help them find prey in murky water, and river otters can hold their breath for five minutes. They often live near beavers and inhabit abandoned beaver lodges. After river otters mate, a fertilized egg remains in the female’s uterus for 10 months before gestation begins. In the spring, females give birth to as many as five "kits" or "pups," which are taught by their mother to fish and swim before going their own way at age one.

But it is the otters’ humorous antics—sliding down muddy or snowy riverbanks, for example—that makes them most memorable. "Once you’ve seen river otters in the wild, you never forget it," says Carol Peterson of the River Otter Alliance, a conservation group in Englewood, Colorado. "They are the clowns of the animal world, and they are incredibly bright."

American Indians revered these animals and European settlers marveled at river otters’ abundance, naming several places after the creatures—from Otter Mountain in Colorado to Bayou de Loutre (French for otter) in Louisiana. But trappers keen for the animal’s lush fur systematically wiped out otter populations as the frontier moved west. Habitat loss and water pollution pushed river otters closer to the brink. Nowhere was the decimation of river otters more complete than in the arid Southwest, with its scarce wetlands and harsh environment. By the middle of the last century, river otters were believed eliminated from Colorado, Utah, New Mexico and Arizona.

In the 1970s, many states declared otters threatened or endangered and outlawed trapping, which allowed some populations to return. And several states began reintroducing the species to its former habitats. In 1976, Colorado became the first state to release relocated river otters. Minnesota, Arizona, Missouri, Oklahoma, Pennsylvania and 15 other states followed, and to date more than 4,000 river otters have been released.

When the first reintroductions were conducted, states often obtained otters from places with thriving populations, such as Alaska, Louisiana and Canada. But some reintroductions were carried out before rivers were checked for remaining native populations. Northern Arizona University researcher Joseph Shannon says this may have been the case on the Verde River in Arizona, where out-of-state otters were released in the 1980s. After the "reintroduction," reports began trickling in that otters had inhabited the Verde all along.

Colorado has been a leader in the effort to restore otter populations since its first reintroduction along the South Platte River in 1976. Although that effort failed, the state followed up with four more releases from the late 1970s through 1991, using otters from across the continent. A reintroduction in Rocky Mountain National Park at the headwaters of the Colorado River has been particularly successful, as annual otter counts have documented a stable population. In addition, reintroduced otters have gained a foothold on the Dolores, Gunnison and Green Rivers. In the spring of 2002, Colorado hired Polechla to survey the San Juan, Piedra and Los Pinos Rivers, in the southwestern part of the state, to see if otters reintroduced to the Piedra had established a breeding population.

Polechla is a lumbering man with wide eyes and a sincere manner. He signs off e-mails, "I otter be going." Asked what intrigues him about river otters, he replies: "Their curiosity. They are investigators. They turn over rocks and swim under log piles. They have to explore for their food, then they have to hunt it, subdue it and eat it, and that’s dangerous work, on top of being frustrating. Their curiosity brings out my curiosity."

Like a sleuth searching for clues, Polechla’s curiosity is on full display as he works his way along the San Juan River. Wearing fishing waders and a backpack filled with equipment, he scours the ground with his eyes, paying extra attention at oxbows, islands and beaver dens—likely otter hangouts.


DOWN TIME: Otters use rivers to travel and search for food, but they spend half their time on land. One of their favorite terrestrial pastimes is sliding down muddy or snowy embankments, like this otter in Montana. The animals’ thick fur—3,000 hairs per square inch—keeps them warm while sledding or swimming in chilly conditions. But their lush coats also made them prime targets for trappers, and helped lead to the decimation of Sonoran otters.

After finding no otter sign the first day, Polechla searches farther upstream the second day. While lower stretches of the river were muddy and turgid, the upper San Juan rages over boulders and through deep canyons of Ponderosa pine and Douglas fir. Suddenly, something catches Polechla’s eye, and he climbs down the 10-foot embankment to a strip of silt at river’s edge. There, below an inch of water, is a tiny footprint. An untrained observer would have walked past, oblivious, but to Polechla the otter sign is as obvious as a billboard.

A juvenile otter passed by recently—perhaps to eat its prey on the riverbank— and stepped in the mud with its right front foot. Polechla measures, sketches and photographs the track and writes its location. A quick search of the riverbank nearby reveals several scat piles of crayfish shells and fish bones—"probably carp or sucker," he says. Otters feast on these slow-moving bottom-feeders.

Since Colorado released no otters into the San Juan, Polechla speculates this juvenile journeyed upstream from the Piedra. He bags some of the scat for testing. (If he can get funding, Polechla plans to compare the DNA of the scat with a sample taken from the mounted specimen in his office.) The print and scat were the only otter sign he would find during the course of three days on the San Juan.

While they remain scarce in the Southwest, otters have rebounded in other parts of the country such as the Northeast, where sightings and road kills have become more frequent. "They are coming back," says New York biologist Dennis Money, who calls the species’ return "a tremendous success.’’

Money oversaw a recent reintroduction of 279 river otters from the Adirondack and Catskill Mountains to the Finger Lakes region of New York. Rochester Gas and Electric, for whom Money works, funded much of the project. Public schools also chipped in, including a kindergarten class that donated $35 in pennies. The relocated otters appear to be faring well, based on the number of public sightings.

Thanks in part to reintroductions such as this, river otters now inhabit nearly 90 percent of their historical range. Although there are no accurate nationwide counts, otter populations appear to be highest around the Gulf of Mexico, along the Atlantic coast, the Great Lakes and the Pacific coast. Ohio recently removed otters from its endangered species list. The animals are thought to live in every state except New Mexico, and 28 states now have trapping seasons.

But otters are still absent from many rivers in the Southwest, leading to proposals for more reintroductions. The highest-profile initiative involves the Grand Canyon, where the creatures have not been seen since the 1950s. Leading the charge to bring otters back to this national landmark is David Wegner, a consultant who previously worked in the canyon for the Interior Department.

"While the canyon would survive without river otters," Wegner says, otters are part of its "natural ecological heritage." Shannon of Northern Arizona University notes that fish populations are booming in parts of the Grand Canyon, and reintroducing otters would be a natural way to return a predator-prey balance.

While any reintroduction into the Grand Canyon is years away, Polechla nevertheless feels it is crucial to first survey more of the Southwest. If any Sonoran otters are found, they could be protected and perhaps reintroduced to rivers across the region. But Wegner and Shannon say that even if there are surviving Sonoran otters, their numbers are so low that finding enough to relocate would be unlikely.

Whatever the outcome of the Grand Canyon plan, Polechla plans to continue investigating riverbanks across the Southwest for years to come. As this article was going to press, Polechla was seeking funding for a search of New Mexico’s rivers, and participating in a survey of the upper Rio Grande River—an area that he believes could hold some Sonorans. "Otters are secretive, and unless you actively search you stand no chance of finding them," he says.

Asked why he holds out hope of finding Southwestern otters when most others believe they are gone, Polechla’s voice rises. "Scientists hypothesized that the black-footed ferret was extinct. Then a dog brought a freshly killed one to a ranch in Wyoming in 1981. Scientists said the jaguar was extirpated north of the Mexico border; then one was treed in the 1990s on the Arizona-New Mexico border. Scientists said the hairy-nosed otter was extinct until it was found at several sites in Southeast Asia in the 1990s."

"My point," he adds, "is that scientists were wrong in all these cases."

With that, Polechla marches around a bend in the San Juan, a man on a mission to answer the million-dollar question of the wild Southwest.

Colorado journalist Paul Tolme spent several days on the San Juan River with Paul Polechla last summer. To learn more about river otters, see www.eNature.com/riverotter .

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