**Nutria** (*Myocastor coypus*), also known as the Coypu, is a large, semi-aquatic rodent native to South America that has been introduced to North America, Europe, Asia, and Africa. It is one of the world’s most damaging **invasive species**. The conflict is severe and multifaceted: they cause widespread destruction of coastal wetlands by consuming roots and rhizomes, leading to “eat-outs” and soil erosion, and they damage agricultural crops (especially rice, sugarcane, and corn) and critical infrastructure (levees, irrigation ditches) through extensive burrowing.
Taxonomy and Classification
Nutria belong to the class Mammalia, order Rodentia. They were originally introduced globally for the fur trade, and escaped or intentionally released animals established rapidly breeding populations in many suitable habitats. They are highly prolific, allowing for rapid population growth and environmental devastation.
Physical Description
Adult Nutria are large, 16 to 24 inches long (body) plus a 10 to 16 inch tail, weighing 12 to 20 pounds.
- **Appearance (Key ID):** Large, muskrat-like body; round tail that is sparsely haired; small eyes and ears. The most distinctive feature is the presence of bright, orange-red or yellow **oversized incisor teeth** that protrude prominently. They have webbed hind feet.
- **Damage Sign (Key ID):**
- **Burrows:** Large, visible burrows along riverbanks, levees, and ditch banks, leading to slumping and collapse.
- **”Eat-Outs”:** Large, circular areas in wetlands where all vegetation has been completely consumed to the root level.
- **Tracks:** Distinctive large paw prints (with three large toes and webbing) near water sources.
- **Conflict:** Severe environmental, agricultural, and infrastructural pest.
Distribution and Habitat
In North America, Nutria are concentrated heavily in the Gulf Coast states (Louisiana, Texas) and the Pacific Northwest, as well as along major river systems. Their habitat is any freshwater or brackish wetland, marsh, river, pond, or swamp.
Behavior and Conflict
The conflict is overwhelming destruction of natural and engineered environments.
- **Coastal Erosion:** By removing the binding root mats of wetland grasses, they destabilize the soil, making it susceptible to rapid erosion by waves and tides, accelerating coastal land loss.
- **Infrastructural Damage:** Extensive burrowing into levees and dams compromises flood control and irrigation systems, leading to breaches and costly repairs.
- **Disease Vector:** They can harbor and transmit diseases such as leptospirosis to pets and humans.
Management and Prevention
Control is aggressive, coordinated population reduction and exclusion.
- **Trapping:** Use various live traps (transfer cages) or lethal traps (conibear) placed along travel runs and burrow entrances. Trapping is the main method of control.
- **Targeted Hunting/Culling:** Large-scale, coordinated culling programs are often implemented by state and federal agencies to reduce populations in sensitive areas.
- Fencing (buried and woven wire) can protect small, high-value areas.
- Capsaicin-based repellents can sometimes protect specific high-value crops (e.g., bulbs) but must be frequently reapplied.
Conservation and Research
Nutria are managed as high-priority invasive, destructive pests. Research focuses on developing effective and species-specific control methods (e.g., reproductive inhibitors) and monitoring the recovery of wetland ecosystems following population reduction.