Ondatra

Ondatra is a genus of semiaquatic rodents in the family Cricetidae, subfamily Arvicolinae. The best known member is the muskrat, Ondatra zibethicus, which is the only living species currently placed in the genus. The genus also includes several extinct species described from fossil remains.

Native to North America, the muskrat has been introduced to parts of Europe and Asia for fur farming and has established wild populations in many wetlands. It inhabits freshwater environments such as marshes, swamps, ponds, and slow-moving streams, especially areas with abundant emergent vegetation. They often construct lodges or burrows along banks near water.

Muskrats are medium-sized, with dense fur, a laterally flattened tail, and strong hind feet adapted for swimming. They are primarily nocturnal or crepuscular and are active year-round in temperate regions. They build shelters, forage for food, and travel underwater using their nostrils and ears that close underwater.

The diet is mainly aquatic vegetation, including cattails, reeds, and water lilies, supplemented by roots and tubers. They may opportunistically eat invertebrates. Through their feeding and dam-building, muskrats influence wetland plant communities and animal habitats.

Breeding occurs from spring into late summer in warmer areas. Litter sizes commonly range around 6–8, with several litters possible per year under favorable conditions. Gestation lasts about 28–30 days. IUCN lists the muskrat as Least Concern due to its wide distribution and large populations, though local declines occur from habitat loss and trapping.