River otters were once endangered in Illinois, but now they’re thriving across the state thanks to a successful reintroduction effort in the 1990s.
Pay close enough attention for long enough, and you just might see the critters in Chicago. The Forest Preserve District of Cook County’s habitat restoration efforts and the Illinois Department of Natural Resources’ reintroductions of the river otter mean they are no longer on the state’s endangered species list, according to the Outdoor Illinois Journal.
Over the past few years, biologists have even captured a few of the mammals here in Cook County through the Urban River Otter Research Project, through which scientists hope to learn how otters are adapting to the urbanization that once drove them out.
Chris Anchor, one of the scientists working on the project, told WBEZ’S Reset he recently saw an otter near Union Station.
“I was pulling jury duty one day and I took the train in and got off at Union Station,” he said. “As I’m crossing the river with thousands of other workers that morning, I went down in the river near where an otter was grooming itself, with a pile of carp skulls next to it. Oh my goodness. I looked around and no one else was aware of its presence and it was just absolutely amazing that the animal was where it was at. It was just there, minding its business.”
Back in 1989, scientists estimated there were only about 100 otters left in Illinois, mostly because of habitat loss and, to a lesser extent, exploitation of trapping of the animals. Now, there are more than 20,000 otters in the state.
They’re so prevalent downstate that they’re actually causing some problems, especially for folks with private ponds, Anchor said.
“A family of otters can move in and pretty much wipe out all the fish in a night or two,” he explained. “And I imagine it can be pretty frustrating to a homeowner to look out one day and see all the fish lined up on the shoreline with their bodies removed.”
Zach Hahn, a graduate student at The Ohio State University — one of the Urban River Otter Research Project’s partners — said researchers are currently working on figuring out where the otters are in the state.
A few otters were under surveillance when the COVID-19 pandemic hit, which disrupted operations, Hahn explained. Researchers lost contact with the otters or simply failed to spot them again.
“So now we’re just in the process of trying to find out where they’re hanging out again and we use trail cameras for that,” Hahn told Reset. “We’re also using a rather new — not new to the study of otters but new to the Chicago area — a wildlife reporting survey. We created the otter sighting reports and the link is available on our Facebook page.”
Researchers with the Urban River Otter Research Project have captured seven of the animals so far, using care to not hurt them in the process.
Once the otters are captured, the scientists work with the Brookfield Zoo to surgically implant transmitters into the marine mammals — which Hahn said is necessary because otters do not have necks, so scientists can’t put collars around them the way they would with deer or coyotes.
In 2015, local researchers helped trap the first otter at the Sand Ridge Nature Center in South Holland. The otter had roamed dozens of miles to visit different groups of female otters. Anchor described the experience and said researchers “really don’t know” yet if that case was normal for river otters in general.
“That first animal was a young male and rather typical, if you look in the literature for predators in general, the young males tend to forge out on their own,” Anchor said. “They’re looking for an occupied territory and receptive females. Once he realized he had no females at Sand Ridge, he dumped into the Grand Calumet and then into the Des Plaines River and then he went west all the way to [the village of] Lemont, and then ultimately down by Romeoville. And he lived until the transmitter died, visiting two different groups of females out in that area.”
The new work from the Urban River Otter Research Project will build on previous studies like the one Anchor described, as well as a separate, Urban Coyote Research Project. The coyote project focused on researching the animals’ behavior in urban environments so humans could learn to better co-exist with them.
“As is typical with most wildlife when it gets into an urban setting, their behavior patterns and strategies to survive many times change dramatically,” Anchor said. “Even with the small group of animals that we’ve already handled, we found out some things that we had no idea about.”
Anchor described examples of otters moving through backyards and neighborhoods to travel between ponds.
Scientists say the fact that otters are returning to the Chicago River suggests that the water quality is improving — which is good news not just for wildlife, but for people as well.
Before legislature passed in the late ‘60s and early ‘70s, the water quality was “exceptionally poor” in the Chicago area, Anchor said. He described growing up near the Des Plaines River, which at the time had only two to four species of fish and hosted a layer of muck at the bottom.
Since the passage of the Clean Air and Clean Water acts and the removal of head dams, the Des Plaines River now has more than 40 species of fish. Anchor said the layers at the bottom have completely disappeared, replaced by sand, gravel and rubble.
“We’ve dramatically improved not only the water quality, but the habitat of the river itself,” Anchor said. “It’s actually a river now.”
If you’re eager to spot an otter in the Chicago area, Hahn recommends trekking through the forest preserves, which are a haven for wildlife. Otter tracks are distinctive: Look for five-digit footprints (dogs only have four toes) with wide pads that differentiate them from those left by raccoons. Finally, otters like to slide, so keep your eyes peeled for their slick paths straight into the water.
“It’s a great underdog story that what once drove otters out of the Chicagoland area — they’re kind of figuring out ways to overcome it and make it their own,” Hahn said.