State of Montana Website Montana State Parks Website



  • Myocastor coypus
  • A large rodent from South America; grows to 15-20 lbs, 25 inches in length
  • Originally introduced for fur farms
  • Degradation of habitat, destruction to agricultural crops and damage to infrastructure is well documented in areas where nutria have become established
  • Feeding habits make them extremely destructive to marsh vegetation
  • Eat up to 25% of their body weight per day
  • Populations grow rapidly, reproduce frequently (2-3 times annually) and mature early (4 to 6 months old)