In the 20th Century, we preserved the land. In the 21st, let’s restore it.

In the News

November 12, 2015

Forest Preserves of Cook County, Chicago Zoological Society study habits of urban river otter

A century after near-extinction from the State of Illinois and decades after reintroduction, an urban river otter has found its way into the southern region of the Forest Preserves of Cook County, calling an isolated pond within the preserves home.

The Forest Preserves of Cook County and the Chicago Zoological Society (CZS), which operates Brookfield Zoo, have since collaborated to study the otter’s behavior. CZS veterinarians surgically implanted a transmitter in the otter, allowing wildlife biologists to track how the animal moves and learn how far the otter travels from its home base, while hopefully leading researchers to other otters in the area.

“We’re very excited to be able to work with the wildlife biologists from the Forest Preserves of Cook County on this project,” said Michael Adkesson, DVM, Dipl. ACZM, vice president of clinical medicine for the Chicago Zoological Society. “This project is just one of many ways that the Society collaborates with the County to act locally for the conservation of wildlife and nature.”

“We currently have otters in all of the watersheds in Cook County, but at very low numbers. 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 Chris Anchor, senior wildlife biologist for the Forest Preserves of Cook County.

According to Anchor, river otters are an alpha predator in the local wetland system, and rely on the health and well-being of the entire system beneath them. 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.

“We are several years into an otter study. Urban otters, as with most urban wildlife, behave completely different than animals in a rural environment. There are many questions we do not understand about the ecology and natural history of otters that we’re hoping to answer through the use of telemetry,” said Anchor.

Within the implanted transmitter is a coiled antennae that emits signals. Using a directional antennae to pick up the signals, a process called triangulation, researchers are able to locate the otter to better study the animal and its habits, habitats and travel routes.

“The habitats of Cook County are diverse and in close relation to one another. By tracking the otter’s movement, we are learning how it’s using right of ways through neighborhoods and commercial property – this is all new information we’re receiving,” said Anchor.

For more information on the Forest Preserves of Cook County, visit To learn more about the Chicago Zoological Society, visit

Sondra Katzen
Chicago Zoological Society