Cook County Otter Outfitted for Spy Mission

North American river otter recovery in the Chicagoland area took a surprising leap forward this fall with the capture and release of an otter in southwest Cook County. A few decades ago, Illinois’ river otters were almost extirpated and listed as “state endangered”. State reintroduction efforts in the 1990s significantly improved their numbers, but evidence of otters thriving in the urban interface of Cook County was slim-to-none.

Chris Anchor, senior biologist with the Forest Preserve District of Cook County (FPDCC), enlisted USDA Wildlife Services (WS) to monitor for otter presence in the county. After years of surveying waterways for tracks and scat, promising signs were spotted this May in an isolated spot. WS trail cameras confirmed an animal’s presence, and trapping efforts began. Finally, after many thwarted attempts, WS staff captured the elusive otter using a modified foothold trap.

At FPDCC’s affiliate Brookfield Zoo, veterinary staff surgically implanted a radio-transmitter in the otter. The small device will allow biologists to track the otter to determine its movements throughout the area, den locations, foraging habits, and possibly interactions with other otters. Technicians from WS, FPDCC, and the Max McGraw Wildlife Foundation are collaborating to track the otter.

“We’re trying to understand what their challenges are, and to see if there is anything we can do to promote their population within Cook County,” explained Anchor.

Otter population recovery is almost impossible without the proper habitat – clean waterways with healthy and diverse fish populations. Considerable efforts have gone into the preservation and restoration of native landscapes within the county. This otter presents an undeniable sign that the Forest Preserve District of Cook County has made great strides in protecting and improving its diverse ecosystems and enabling the presence of sensitive species that rely on wild and clean habitats on the 69,000 acres it manages.

A native Illinois species, river otter were common until unregulated harvest and habitat loss led to declining populations in the late 1800s. In 1929 the otter trapping season was eliminated, with limited effect, and otters were listed first as threatened (1977) and then as state endangered in 1989. With laws and conservation efforts to improve water quality, an Illinois Department of Natural Resources otter recovery effort began in 1994 with great success. Otter were delisted in 2004 and a trapping season was reinstated in 2012-13.

A North American river otter is released back into the southwest region of the Forest Preserves of Cook County. By understanding river otters’ habits, researchers will be able to better identify where to restore various open land to benefit the health of otters and the biodiversity of all wildlife and humans. Image Credit: Chicago Zoological Society. This released river otter will be tracked to gain a better understanding of the animal’s habits, habitats, and travel routes, which will help determine what the otter’s challenges face in an urban setting and what can be done to promote their population within Cook County. Image Credit: Jeff Nelson. Trail camera evidence confirmed the presence of the Forest Preserves District otter, which proved elusive for months. Image Credit: USDA Wildlife Services. The WS team that captured and will track the otter includes biologist John Hartmann and specialists Hannah O'Malley and Dan Fiorenza. Image Credit: Jeff Nelson

See more from Brookfield Zoo at Dr. Mike’s Video Blog: River Otter Study.  

Wildlife Services is a Strategic Partner of TWS.