Ecologists are studying elusive river otter in Lake County
When Andrew Rutter took a full-time wildlife ecologist position at the Lake County Forest Preserves in 2017, he expected his work studying river otter ecology would come to an end. That's not the case.
One of Rutter's roles here is to expand the monitoring program of semiaquatic mammals, which includes recovering North American river otters (Lontra canadensis), a species that's becoming more abundant in Lake County.
Rutter spent two years studying river otter ecology while earning his graduate degree in southern Illinois, where the mammal is relatively abundant. I asked him some questions about this elusive animal.
Q: Tell us a bit about how river otters became endangered?
A: Because river otters were (and still are) sought after for their fur, river otter populations experienced rapid declines before state agencies began regulating their harvest. Many other species experienced declines for similar reasons throughout the 19th and early 20th centuries, as well. Habitat loss in the form of destruction and degradation of wetlands and streams likely also played a role in their decline.
Q: How and why have river otters rebounded since the 1990s?
A: The Illinois Department of Natural Resources started a translocation and reintroduction program into Illinois. Wetland and stream protection and restoration programs have resulted in higher quality habitat for the reestablished populations.
Q: How does human activity or land development affect otters?
A: That's one of the questions my collaborative project with the Southern Illinois University Cooperative Wildlife Research Laboratory hopes to shed light on.
River otters were once considered a "canary in the coal mine" of sorts; it was thought that they could only inhabit the most pristine aquatic habitats. However, river otter populations are persisting in degraded urban areas, where it was once thought they could not.
We want to understand how these animals are adapting to this stressful urban environment, as well as potentially benefiting from our restoration efforts. Humans still represent a major threat to river otters through both habitat destruction, and by direct mortality via trapping and vehicle collisions.
Q: How do you monitor otters and other semiaquatic mammals in the preserves?
A: My collaborative project with SIU is focused on randomized sign surveys. Devin Hoffer, my graduate student collaborator, and his field technicians search for scat (droppings), tracks and feeding signs of otters and other semiaquatic mammals along shorelines.
Additionally, our staff, wildlife monitoring technicians and volunteer river stewards enter pictures of any unique scat or tracks they find into our Mobile Ecologist Web Application (mECO) for the ecologists to review.
Q: You studied otters in southern Illinois. Were you expecting them in Lake County?
A: We radio-tracked river otters in southern Illinois to some pretty heavily degraded areas. While I wasn't expecting to find them in Lake County initially, I wasn't surprised when they started turning up more frequently.
They're also an elusive animal. It takes experience to accurately identify signs they leave on the landscape.
Q: Where can river otters be found in Lake County?
A: I get this question fairly frequently. River otters are carnivores, and prefer remote aquatic habitats with ample prey resources. They have to stay fairly mobile to access the food they need.
The otters we tracked in southern Illinois averaged home ranges of about 10 square miles. Wetlands, rivers, streams, ponds and lakes all provide good river otter habitat. They dig underground dens close to the water's edge, burrowing out multiple tunnel openings to enter and exit. Female river otters deliver litters of one to six young in these burrows.
Q: What are some key signs of an otter's presence?
A: River otters leave very distinctive scat in strategic locations as a "calling card" to communicate with other otters in the area. The scat, or "spraint," is an amorphous blob of fish scales and crayfish parts that has a characteristic musky odor. When you've smelled enough of it, as I have during my research, you'll recognize it immediately, and you can sometimes smell it before you see it.
Q: What do otters look like?
A: River otters are the largest member of the weasel family (Mustelidae). They weigh between 10 and 30 pounds and are about 3 to 4.5 feet long. They actually look like an oversized ferret. We jokingly referred to them as "furry cat snakes" in graduate school.
While they are agile swimmers, on land they have kind of an awkward lope. Imagine if you gave a Slinky fur and legs and saw it bounding down a shoreline.
Q: Are there other local animals that look similar?
A: Mink are a semiaquatic cousin of the river otter. They're fairly common in Lake County and live in similar habitats. However, an adult mink is typically less than half the size of an adult river otter. When swimming, beavers and muskrats can also be mistaken for river otters.
Q: Why do they say otters are social animals? What are common otter behaviors?
A: Otters are unique among members of the weasel family in that they readily form social groups. While family groups are typical, both related and unrelated otters will band together to increase their ability to catch aquatic prey.
They can also be quite playful. Researchers are just starting to unveil the complexities of their social interactions.
Q: What do otters eat?
A: Fish and crayfish are their primary food sources, but they are opportunistic carnivores. They will also eat small mammals, reptiles, amphibians and birds when they can catch them. I've even heard of them raiding chicken coops.
Q: Why is it important that we understand river otter populations in Lake County?
A: As top carnivores, river otters play a unique ecological role. Simply having them on the landscape can have far-reaching impacts on other species in the food web. Their unique habitat requirements make their presence on the landscape a great litmus test for the quality of our restoration efforts.
To me, river otters, and wild carnivores in general, represent true wildness in an area experiencing profound habitat reduction and degradation. Understanding why they are here should be a top priority if we are to be devoted to ecological conservation.
Q: What might we expect in the future for Lake County river otters?
A: Hopefully we will see persistence of the current population, as well as increasing numbers. We are working steadily with other conservation organizations to do what we can to preserve aquatic habitat and increase restoration efforts in Lake County, but we can only do so much to combat urban sprawl and its associated negative impacts to aquatic habitats.
Q: Can citizens take any local actions to protect river otters?
A: Supporting conservation initiatives put forth by our agency, IDNR, Citizens for Conservation, U.S. Fish and Wildlife Service, and The Nature Conservancy can go a long way. Every acre of aquatic habitat preserved is one less acre that can potentially become developed and one more acre of potential habitat for river otters. Improving the quality of aquatic habitats on your own property can also play a big role.
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Andrew Rutter
Wildlife Ecologist Andrew Rutter grew up camping, hunting, fishing and trapping, activities that sparked his interest in wildlife and the outdoors. After earning a biology degree at Emporia State University in Kansas, he took a seasonal internship with Southern Illinois University working on behalf of the Lake County Forest Preserves as an ecological field technician.
Then he earned a master's degree in forestry with the Southern Illinois University Cooperative Wildlife Research Laboratory, studying river otter ecology.
"Learning about biology and ecology made me realize how diverse and interesting the field is," Rutter said.
A little more than three years ago, Rutter started his career at the Lake County Forest Preserves to help manage a long-term wildlife monitoring program and various wildlife research projects.
• Kim Mikus is a communications specialist for the Lake County Forest Preserves. She writes a bimonthly column about various aspects of the preserves. Contact her with ideas or questions at kmikuscroke@LCFPD.org. Connect with the Lake County Forest Preserves on social media @LCFPD.