Illinois Department of Natural Resources
August 2017
August 1, 2017

The Comeback of the Chicagoland Otters

By Dan Fiorenza, Chris Anchor

Photos by Michael R. Jeffords.

Once a declining species in Illinois, increasing populations of North American river otter (Lutra canadensis) in the Chicagoland region has been a true success story of the consistent conservation strategies carried out by the Forest Preserve District of Cook County.

River otters were almost extirpated from Illinois in the early 1900s due to overharvesting and degradation of vital habitat by early settlers. Despite stricter regulations placed on harvesting river otters during the mid-1900s, the continual decline of habitat and water quality in the region contributed to the diminishing river otter population in northern Illinois. In 1989 river otters were placed on the Illinois endangered species list and were a top priority for conservation agencies to protect.

Boosted by extensive habitat restoration efforts by the Forest Preserve District of Cook County and downstate reintroductions by Illinois Department of Natural Resources, river otters are now becoming a common species in the Chicagoland region and are occasionally sighted in local waters. River otters have made such a tremendous comeback that they were delisted in 2004, and, after almost 100 years, the Illinois river otter trapping season was reopened during 2012-2013.

An otter standing on top of a fallen log.

During the fall of 1991, the first sighting of a river otter occurred in the Chicago region which sparked the interest of conservation professionals to monitor otters’ use of the region and observe whether or not they were beginning to return to the area. It was the fall of 2002 when river otters became a more common presence in the region and clear signs of activity were starting to be observed. The Forest Preserve District of Cook County then launched a long-term surveillance program to monitor the presence of river otters and to research how their behavior responds to the dense urban environment.

In 2008, the Forest Preserve District of Cook County began working with USDA-Wildlife Services in order to expand their monitoring efforts and increase the number of staff-hours spent in the field searching for otter sign (e.g., latrine sites, slides, dens). Using trail cameras, visual observations, trapping and radio telemetry, several individual otters and some breeding populations have been located in the region.

In the fall of 2015, wildlife specialists from USDA-Wildlife Services successfully captured a male river otter, which was returned to the wild after being implanted with a radio transmitter by Brookfield Zoo veterinarians to help monitor its movements. Efforts by Wildlife Services and other cooperators in tracking river otters with radio transmitters has provided significant knowledge on how otters are able to mobilize across different urban landscapes as well as challenges they may face.

The growing river otter population in northern Illinois is an incredible opportunity for wildlife viewers and trappers. River otters can be observed in the Calumet, Des Plaines and Chicago rivers at various times during the year. Ongoing conservation efforts by the Forest Preserve District of Cook County and Wildlife Services will ensure that these populations of river otters will remain for public and ecological benefits in the future.

Dan Fiorenza is a Wildlife Specialist with the USDA-APHIS-Wildlife Services and based in Orland Park. Chris Anchor is a Senior Wildlife Biologist with the Forest Preserve District of Cook County and based in Elgin.

An otter resting on a log submerged in water.