Nutria are large, semi-aquatic rodents whose potential impact on human activity and natural ecosystems is a subject of public interest. Understanding their biology and behaviors can clarify the dangers they pose and how to interact safely with them.
Understanding Nutria
Nutria are sizable rodents, weighing 15 to 20 pounds, with bodies around two feet long and tails adding another foot to a foot and a half. They have dark brown fur, large orange incisors, partially webbed hind feet, and long white whiskers. Native to South America, nutria were introduced to non-native areas like the United States in the late 1800s and early 1900s for fur farming. Many escaped or were released after the fur market declined in the 1940s. They thrive in aquatic habitats such as wetlands, marshes, and rivers. Nutria are primarily herbivorous, consuming roots, rhizomes, tubers, and stems, and can eat approximately 25% of their body weight in vegetation daily.
Threats to People and Animals
Nutria can pose threats to humans and domestic animals. While direct attacks are uncommon, they may bite if cornered, provoked, or if they perceive a threat to their young. Such bites can lead to infections. Nutria also carry and transmit diseases that affect humans and pets, including leptospirosis, salmonellosis, giardiasis, tuberculosis, and septicemia. Transmission occurs through contaminated water (often from feces and urine) or direct contact. They can also host parasites like nematodes, which may cause “nutria itch,” along with tapeworms, liver flukes, and blood flukes.
Impacts on Environment and Property
Nutria are an invasive species known for their destructive impact on the environment and property. Their extensive burrowing causes significant erosion of riverbanks, levees, and dikes. These burrows can also weaken structural foundations of roads, buildings, dams, and culverts, increasing the risk of flooding and infrastructure damage. Nutria’s voracious appetites contribute to widespread environmental degradation. They consume up to 25% of their body weight in vegetation daily, often destroying up to 10 times the amount they consume. This feeding damages agricultural crops like sugarcane, rice, corn, and various vegetables. Their grazing on native vegetation also degrades habitats, reduces biodiversity, and converts marshlands into open water environments.
Safe Encounters and Control
If encountering nutria, observe them from a distance. Avoid feeding them, as this encourages them to lose their natural wariness of humans. Keep pets on leashes in areas where nutria are present to prevent unwanted interactions. Property owners can deter nutria by removing food sources and installing fencing, typically at least four feet high with one foot buried underground. Wildlife management authorities employ broader control measures, including trapping (leghold and body-gripping), habitat modifications (vegetation removal and water level manipulation), shooting, or controlled use of toxicants like zinc phosphide. If nutria cause problems or appear sick, contact local animal control or wildlife agencies for professional assistance.