are swimming rodents similar to beavers and muskrats with long, thin tails.
These rodents have not been sited in Pennsylvania but a risk of invasion
is possible from neighboring states.
Nutria inhabit fresh and brackish marshes, rivers, bayous, farm ponds, freshwater impoundments, drainage canals, swamps and various other types of wetlands.
Although now found in more than 15 U.S. states, their native range includes Argentina,
Chile, Bolivia, Uruguay, Paraguay and southern Brazil.
Nutria may weigh up to 9 kg (20 lb), but on average weigh between 5.5
to 7 kg (12-15 lb), with males slightly larger than females. They have
dense, grayish underfur overlaid by long glossy guard hairs that vary
in color from dark brown to yellowish brown. Their large front teeth are
yellow-orange to orange-red on the outer surface. The forepaws have four
well-developed clawed toes and one non-functional toe. The hind feet have
five clawed toes: four webbed and one that hangs free.
Nutria were intentionally brought to America for fur ranching. During
World War II fur prices collapsed and many ranchers lost interest and
released animals into wild marshes where they quickly became established.
Nutria are now reported in every Maryland Eastern Shore county and are
found from Bombay Hook National Wildlife Refuge in Delaware through the
Delmarva Peninsula to Virginia's Eastern Shore. They have also been reported
on the western shore of Maryland in the Potomac and Patuxent Rivers and
in Virginia as far south as the Northern Neck near the Rappahanock River.
highly prolific and breed all year. Litters average four to five young;
however, nutria can have up to thirteen young per litter and may have
three litters per year. Young are born fully furred and active. They can
swim and eat vegetation shortly thereafter, still feeding on mother’s
milk for up to eight weeks. Within five days of life, nutria can survive
away from the mother.
As an example
of their proliferation: in 1938, 20 individual nutria were introduced
into Louisiana and within 20 years, the nutria population exceed 20 million
animals. By 1962, the nutria had replaced the native muskrat as the leading
furbearer in Louisiana.
2010 Distribution of Nutria
Nutria feed primarily on marsh vegetation that extends above the waterline.
They are opportunistic feeders with an extremely varied diet. They consume
about 25 percent of their body weight daily. Nutria use their beaver-sized
incisors and powerful forefeet to dig under the marsh surface to feed
directly on the root mat, leaving the marsh pitted with holes and deep swim canals. Areas
devoid of vegetation are called "eat outs" and the swim canals
are called "runs."
easily convert productive grassy marsh into unproductive open water by
attacking the very structure that holds the marsh together, the vegetative
root mat. Once the nutria chew through the mat and expose the mud, tidal
currents and wave action lead to erosion. The marsh surface sinks and
the vegetation is lost to flooding. Areas destroyed by nutria become permanent,
open water ponds.
to destroying areas of marshland, they compete for habitat and food with
native muskrat species and carry a parasite that causes marsh itch in
Louisiana has instituted a Nutria Control Program (along with promotion
of nutria meat as a high protein low fat food source). “The Coastwide
Nutria Control Program” consists of an economic incentive payment
of $4 per nutria tail delivered by registered participants to collection
centers established in coastal Louisiana. The goal of the Program is to
encourage the harvest of up to 400,000 nutria annually from coastal Louisiana.
To read more, view the Pennsylvania Sea Grant Nutria fact sheet.
FOR MORE INFORMATION ON NUTRIA