Oryzomys couesi, Coues's rice rat, is a semiaquatic rodent occurring from southernmost Texas south to northwestern Colombia. It is usually found in wet habitats, such as marshes, but also lives in drier forests and shrublands. It is a medium-sized to large nocturnal rat with coarse fur, usually brownish to reddish above and whitish below, although there is much geographic variation in size, proportions, color, and skull features. An excellent swimmer and diver, it builds nests of vegetation suspended among reeds. Its diet includes seeds and insects. It probably breeds year-round, and females give birth to about four young after a pregnancy of 21 to 28 days. This species may be infected by parasites and hantaviruses. It was first described in 1877, and related forms were eventually merged into a single species. This rat is common, and even locally considered a pest species, but some populations are threatened. (This article is part of a featured topic: Oryzomys.)