(This is the second in a series on Invasive Species in Virginia)
By Ron Messina/DWR
It’s a typical summer afternoon on the Upper Chickahominy River. There’s a scattering of small fishing boats, and tons of wildlife everywhere you look—frogs, geese, turtles, and ducks. A bald eagle soars away, over the tall pine trees. Massive cypresses, anchored in place with their numerous knees, line both sides of the river’s edge, completing the feel of a bayou. It’s peaceful, serene. You would never know anything could be wrong with this picture. But an animal called nutria (Myocastor coypus) threatens the very existence of this marsh.
Just what are nutria, and why are they so dangerous to this river?
Nutria are large, invasive, semiaquatic rodents. Covered with fur, rat-tailed, and web-footed, they’re similar in appearance to the native muskrat, although much bigger and far more destructive. With their large orange, beaver-like teeth, nutria will eat just about every plant that grows in a marsh. Once established, they are capable of mowing down and digging every available acre of beautiful wetland landscapes, thus turning them into bare patches of mud that then become eroded to open water over time.
Nutria are native to South America, but were introduced into Louisiana and several other states by commercial fur farmers beginning in the late 1800s. Eventually, many of the fur farms went bust and the nutria escaped or were released into the wild.
Nutria crossed into Virginia from North Carolina, slowly creeping their way along the eastern coastal rivers and wetlands. It took them 50 years to expand their range north of the James River, but the Chickahominy is currently the northernmost river system they’ve entered in Virginia.
That’s why it’s so important to stop them before they become established in the Chickahominy River and before they have a chance to wreck the pristine habitat. The Chickahominy is just a steppingstone or gateway to all the rivers north and west.
Ultimately, what makes nutria so bad is that they outcompete native wildlife by destroying their habitat. They dig up and eat the root systems in the emergent vegetation, and plant systems aren’t able to recover. They destroy what’s holding those soils together. When you have big rain events, you get erosion, and we end up losing our marshes and all the wildlife that depend on them.
Nutria are prolific breeders, reaching sexual maturity in four to six months and breeding year-round in most of their range. They produce up to three litters each year of four to five young, a reproduction rate that left unmanaged can quickly lead to thousands upon thousands.
In the wild, nutria rarely live longer than three years. Most adult nutria weigh between 15 to 30 lbs.
Nutria can eat 25 percent of their body weight in vegetation in a day, and they feed year-round. They dig up the roots of plants to eat, destabilizing the soil.
They are indeed an invasive species.