Submerged otters undergo a slowed heart rate to conserve oxygen, but they can remain submerged for only about four minutes at a time. They feed primarily on small minnow-sized fish and crayfish, but also consume crabs, amphibians and a variety of other aquatic prey species. Otters are nocturnal but may occasionally be seen in daylight hours. Bands consisting of five to ten adult otters are occasionally observed, and two or more otters have been know to hunt cooperatively by herding fish. Dens are often bank burrows vacated by other animals, but my also be located in log jams, natural cavities or thick vegetation.
Dens are temporary except when raising young.
These charming creatures usually mate for life. Breeding in the spring, females exhibit a period of delayed implantation that lasts from 290 to 380 days. Add an active pregnancy of 60 to 63 days, and otter pups may be born more than a year after the female has been successfully bred. Pups are born fully furred, but are blind for the first five weeks. They are weaned in three months and remain with the mother for almost a year.