River otters are found throughout Illinois. Their presence represents a significant conservation achievement, transforming them from a nearly extirpated species to one now common in every county. This recovery highlights the effectiveness of dedicated wildlife management efforts.
A Remarkable Comeback
River otters were once abundant across Illinois waterways. However, their populations severely declined due to habitat loss, water pollution, and unregulated hunting and trapping. By 1989, fewer than 100 river otters remained, leading to their classification as a state endangered species.
The Illinois Department of Natural Resources (IDNR) initiated a recovery plan in the mid-1990s. Between 1994 and 1997, 346 river otters were relocated from Louisiana and released into central and southern Illinois watersheds. These reintroduction efforts were monitored to track adaptation and spread.
The reintroduction proved successful, with populations steadily increasing. By 1999, their status improved from endangered to threatened, and by 2004, river otters were removed from the state’s endangered species list entirely. The population continued to rebound, reaching an estimated 11,000 by 2009, and is now documented in all 102 Illinois counties.
Where They Live and What They Eat
River otters inhabit various aquatic environments, including rivers, streams, lakes, and wetlands. They prefer areas with clean water and ample food, often utilizing nearby timber and abandoned beaver dens for shelter. While otters do not dig their own burrows, they adapt to available cover along waterways.
Their diet primarily consists of aquatic animals, reflecting their role as top predators in freshwater ecosystems. Fish and crayfish are staple foods, but otters also consume frogs, salamanders, small turtles, aquatic insects, and earthworms. They have a high metabolism, requiring significant daily food consumption, often pulled onto land to eat.
Spotting River Otters
Spotting a river otter in the wild involves observing their physical characteristics and tell-tale signs. They have a long, streamlined body, short legs with webbed feet, and a thick, tapered tail that can make up about one-third of their total length. Their fur is typically dark brown to nearly black, with a lighter, often grayish or tan underside.
Evidence of their presence is often found along riverbanks and shorelines. Otter tracks are distinctive, showing five toes with visible claw marks and often some webbing, typically 2.5 to 3.5 inches wide for front feet. They create “slides” on muddy banks or snowy slopes. Their droppings, called scat or spraint, are often found in communal latrine sites near the water’s edge. Scat is dark and contains fish scales or crayfish parts.