The River otter's numbers in Illinois have been steadily declining since the early 1800s. Some reasons for their decline have been unregulated trapping, loss of habitat, and polluted waterways.
River otters were abundant in Illinois up until the 1800's. However, by the 1940s they were considered to be extirpated (no longer found in the area) in Illinois. Since the 1940s the otters have made a small comeback and have been sighted in 33 Illinois counties. They are most abundant along the Mississippi River and along the Cache River System.
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