North American River Otter  Lutra canadensis

Otters are the only truly amphibious members of the weasel family.  The otter’s streamlined body is covered by tightly packed underfur and long, water-repellent guard hairs. The snout and elbow joints are speckled with stiff whiskers called vibrissae.  These vibrissae are a very important tool for capturing prey, because they detect turbulence in the water, and act as a “fish finder”.  The otter’s ears and nostrils seal themselves off during underwater endeavors, making vibrissae an essential tool.

Otters feed on items that are readily available for capture.  A common misconception about otters is that they pursue fast-swimming game fish.  Typically, otters will feed on slower fish such as carp and shad.  Otters have several hunting sessions in a day, swimming and feeding for an hour or more before hauling out to rest on the bank.  Otters have a very rapid metabolism and a meal will pass through their digestive tract in just a few hours.  This gives them boundless energy, but also forces them to eat frequently.

A captive otter has been described as playful, but is more likely guilty of having too much “time on his hands”.  Eliminating the element of chasing prey, an otter’s time spent resting increases.  Otters in the wild will occasionally be seen “playing” (tunneling through snowdrifts, or sliding down muddy banks), but it is more common in juveniles than adults.  This play enforces social bonds, and heightens fighting and hunting skills.

Until recently, River Otters were classified as threatened.  In Illinois, a major factor in their decline was development of riverbanks for commercial and residential uses.  This development removed important riverside habitat for otters, but also polluted many of the major waterways.   Pollution is detrimental to otter hunting strategies, as it relies mainly on sight.  When water is murky, otters cannot see their prey to catch it.  With river clean-up projects and River Otter re-introduction programs, their populations are rising.