Exotics Out Compete – The Nutria Risk to Wetlands

 

swamp rat
Nutria. Myocastor Coypus. Sleek of fur, orange of tooth.

South Louisiana, the Gulf Coast, the jewel-like Atchafalaya region, and agricultural land roundabouts all have a cute but troublesome visitor. Nutria (species Mycastor coypusof the kingdom, Animalia; the phylum, Chordata; the class Mammalia; the order rodentia and the suborder, Hystricognathi; family, Myocastoridae; and, of course, genus Myocastor) is a native of South America. This huge rat’s native area is from the center of Bolivia, to the south end of Brazil, and further on to Tierra del Fuego – the land of fire.

Nutria (species Mycastor coypusof the kingdom, Animalia; the phylum, Chordata; the class Mammalia; the order rodentia and the suborder, Hystricognathi; family, Myocastoridae; and, of course, genus Myocastor) is a native of South America. . .

 

Either intentionally or accidentally, decades ago nutria from ranches and fur farms, back in the first part of the twentieth century, escaped or were set free. Now, the lushly-coated, orange-toothed vegetarian rats exist in troublesome numbers outside their “normal” habitat, with large populations also living in Asia, Europe, and elsewhere in North America.

Much of this text derives from material my partner and I gathered over the years, including notes for a paper decades ago for a conference in Venice, Italy – just when global warming was first becoming an issue. We prepared the Conference work and were going to deliver it pro bona, and had secured funding for travel – but that fell through and we had to cancel. Over the years we did a couple more pieces from various perspectives.

Now it’s time to revisit it, up-date some material, especially reflecting a few comments kindly offered by Catherine Normand, a biologist with the Louisiana Department of Fish and Wildlife. We are lucky here in Louisiana, to have such dutiful professionals working on our behalf. She points out that “ …myocastor derives from the Latin words for mouse beaver …” the rest of that string, Kingdom, phylum, class, order “… is just letting the reader know where they are on the evolutionary tree.” And the thing is not, properly speaking – she tactfully explains– a rat, but a rodent. However, nutria have been called “rats” half in fun, half very much not, for a long time. I’ll probablly continue the bad habbit.

Nutria waddle along the Atchafalaya River Basins wetlands, rife as they are with tasty vegetation.  The furry critters gambol about the place’s moss-softened banks, and they gaze back from their little groups of two or three gregarious creatures to visitors touring the waterways, vivid orange teeth catching the sunlight.  Any swamp ramble in the Basin is likely to bring travelers in contact with these deceptively cute pests.  While seeming to make innocent, dewy, sweet eyes, they actually do enormous damage to coastal areas, primarily Terrebonne Parish.  In these infested areas the effect has been to accelerate coastal erosion, especially if salt-water penetration has acted to weaken storm savaged vegetation networks.

Nutria and America’s Wilderness Treasure

The Atchafalaya Basin occupies much of South Central Louisiana, is bordered by enormous levees (among the largest man-made objects in the New World), and is ringed by historic communities. A scenic semi-wilderness area with a number of habitat zones, The Basin includes sloughs, copses, hardwood forests, cypress swamps, marshes, streams, seasonal ponds, open water, bayous, and related features.

The Basin includes sloughs, copses, hardwood forests, cypress swamps, marshes, streams, seasonal ponds, open water, bayous, and related features. . .

 

An estimated 300 species of migratory or resident birds use the Basin’s lavish resources at one time or other, including a range of diving and wading birds; egrets and herons are commonplace. The extraordinary roseate spoonbills, ibises, and anahingas are not rare. Eagles, ospreys, and both swallow-tailed and Mississippi kites can, from time to time, be seen gliding across a luminous sky.

The value of the Atchafalaya has been recognized. More than two decades ago, back 1996, Governor Mike Foster directed the State Department of Natural Resources in Louisiana to be the Lead Agency with its federal partner, the U.S. Army Corps of Engineers in the fully integrated Atchafalaya Basin Program.  Then Executive Director Sandra Thompson Decoteau lead the Program in an efforts to ensure traditional uses of the Basin, to conserve old-growth forests, to undertake water management projects, and to construct recreational facilities.

myocastor coypus
Nutria, setting off toward near-by vegetation

Today, according to Wikipedia, it’s “the Atchafalaya National Heritage Area … a federally designated National Heritage Area encompassing parts of fourteen parishes along the Atchafalaya River … The heritage area extends the length of the Atchafalaya Basin from the area of Ferriday in the north to the river’s mouth beyond Morgan City. The National Heritage Area is divided into four regions: Upper, Between 2 Rivers, Bayou Teche Corridor and the Coastal Zone. The designation provides a framework for the promotion and interpretation of the area’s cultural and historic character, and the preservation of the natural and built environment. . . .” The long, hard road to get this beautiful habitat designated a Heritage Area had little effect on the lives of resident rodent.

  . . .  a federally designated National Heritage Area encompassing parts of fourteen parishes along the Atchafalaya River  . . .  

 

Because nutria are present in the Basin, artificially introduced outside their natural habitat (but in a habitat which ably supports them) they, too, are exotics.  No one knows just how many nutria populate the Basin, and because the visual impact in a swamp is hard to measure, the damage done within the Basin is hard to measure.  Jeff Marx, of Louisiana’s Department of Wildlife and Fisheries, speculates that nutria chew on floating marsh, what Cajuns call “flotant,” and can damage cypress saplings.

A Day at Lake Martin

Mocastor coypus is big, often bigger than a good sized house cat, with short legs, small eyes situated high on their heads, rear feet are much larger then the fore ones, with four of the five rear digits joined by webbing. Front digits are free, making it easier, no doubt, to rip tasty vegetation from the soil and present the succulent root to the creature’s broad, chisel-like orange teeth. It’s the rat’s enthusiasm for roots, and the resulting death of the entire plant, which creates the problem associated with a bloom of the animal’s numbers.

Pretty opportunistic, and often feeding in the water, the critters will eat a wide range of vegetation: bark, stems, and leaves.  At Lake Martin, part of the enormous Atchafalaya River Basin in central Louisiana, we watch several nutria forage one day. They were not inhibited by our presence, and we stood less than 30 inches from one as it wallowed and squeezed through tightly packed aquatic vegetation. The animal began to worry a large, tall bushy weed. It pushed it, it pulled it, it scraped mud from its base, and it apparently yanked on the stalk near the water line. While it gnashed with its very obviously orange front teeth, the teeth did not seem useful for pulling. As has been reported by other observers, the lozenge shaped rat seemed single-mindedly focused on the root of the plant. Within about four minutes, much of that fibrous, tuber looking matter was showing above the roiled water.

 . . . we watch several nutria forage one day. They were not inhibited by our presence, and we stood less than 30 inches from one as it wallowed and squeezed through tightly packed aquatic vegetation. . .

 

According to expert Guillermo D’Elia, at the University of Michigan, “The pelage,” fur or pelt to lay folks, “consists of two kinds of hair, soft dense underfur, and long coarse guard hairs that vary from yellowish brown to reddish brown. The underfur is dark gray, and it is denser on the abdomen. The chin is covered by white hairs, and the tail is scantily haired.”  Females sport nipples on their backs, because, being in the water much of the time, junior could hardly make proper use of them along her belly.

INTERLUDE

RETURN TO: Nutria, Exotics Out Compete

Nutria often seem cavalier about being watched, and, in addition, they are wont to use floating objects, debris, or logs as feeding platforms. As a result, they are frequently seen by chance travelers calmly gazing about or gnawing on some toothsome bit of vegetation. Dr. Catherine Normand, with the Louisiana Department of Wildlife and Fisheries described the curious life cycle of these rodents, “two things that are incredibly fascinating about their reproductive biology,” she noted,  “and make them a huge problem is first, after a female gestates her litter for 130 days, the kids are born with eyes and ears open and teeth fully grown! This kind of young are called precocial because they are born so well developed and can eat vegetation not long after being born. In comparison, chickens hatch precocial young that are fully feathered and don’t rely on their parents to feed them, but songbirds hatch altricial young that are naked, blind, and can’t take care of themselves so must be fed. Young nutria do still rely on their mothers for about 6 weeks, as she nurses them for supplemental nutrition that they can’t get from the vegetation, teaches them how to survive and avoid predators.”

Then, in addition the biologist pointed out,  “Within 24 hours of giving birth, females go back into estrus and so are receptive to getting pregnant again. So after a young female nutria gives birth for the first time, for the rest of her life she will likely always have both a litter in utero gestating and a litter on the ground!” No wonder the little critters seem to have such a sanguine view of the world!

Chiefly a lowland animal, likely to live in a swamp, marsh, sluggish stream, or torpid lake, Dr. D’Elia writes that nutria have been found up to, “1,190 meters in the Andes.” They are semi-aquatic and mostly active at night, meaning that they lollygag about preening, playing, swimming, grooming, foraging, and eating. The generally care-free aroma which wafts from these mammals is enhanced by their collegial and gregarious nature.  They travel in groups up to a dozen or so, mostly of females with offspring and a single large male. Residing in burrows, often in crude vegetation built nests, they don’t travel far from that site.

The Economic Costs and Benefits of Nutria

No doubt nutria were, in the past, important in subsistence economies, being easy to catch and supplying protein and raw materials.  The general economic importance of fur in human history is staggering. For example, much of the incentive to travel far from Colonial hubs in the New World, and risk all the frontier dangers including confrontation with very effective Indian resistance, was based on pelt trading. The big rat seems to have become commercially important in the 19thcentury. In Louisiana, 1,000,000 pelts or so were harvested during the 1986-87 season. Radical changes in the use of fur in fashion have since fundamentally changed harvest incentives, however. The market, that is to say, determines much of the activity around harvesting nutria.

Indiana Jones Hat
Luxury Hats: Fur Felt Is used in the Production of Quality Head Wear

According to authorities, the nutria was first imported into this countrywith an eye toward developing a profitable fur industry. The businessmen involved believed that there would be a great demand for the luxurious, thick fur in the future, and they thought that the nature of the creature would help guarantee prolific production. Modern-day trappers in the Atchafalaya Basin, such as June Borel (may she rest in peace) of Catahoula and Carl Templet of Pierre Part, could remember when setting traps was as common as putting out crawfish nets.

. . . the rodents have “relations” in undisturbed bliss, surrounded, at first, by roots galore. As a result, their population has soared . . .

 

Presumably, when the hoped for market did not present itself, would-be fur ranchers began releasing the beasts into the American wilds. Names are said, denials are made, and the rodents continue nibbling on roots with the beatific composure and attitude of the just—very unlike the wicked creatures they are.  Meanwhile, the rodents have “relations” in undisturbed bliss, surrounded, at first, by roots galore. As a result, their population has soared. This overpopulation has resulted in nutria consuming most of the available vegetation in some areas of the marshes, causing great damage. Well, maybe they haven’t eaten most of all it, but they sure chow down on a great deal of it. And they have expanded their distribution, taking their capacious desire for rootstock and reproduction with them.

Nutria: Equal Opportunity Pest

While Louisiana has been especially hard hit, nutria have also caused trouble elsewhere in the United States. In their article, “The Effect of Nutria (Myocastor coypus) on Marsh Loss in the Lower Eastern Shore of Maryland: an Exclosure Study,” Michael Haramis & Robert Colona, explain circumstances on the East Coast.  The scientists write that nutria were introduced there in the 1940’s “to bolster Maryland’s Eastern Shore fur industry.” The nutria (Myocastor coypus) has been implicated in the loss of emergent marsh, especially that dominated by Olney 3-square (Scirpus olneyi) along the Blackwater River in Dorchester County. They support the accepted natural history by pointing out that, “Marsh loss was detectable in this region from photographs as early as the 1950s and has accelerated to the present.”

Quality Fur Hats

As in the case of Louisiana and Texas, the little critters do not work alone to bring about this awful change. The factors are the same: changes in water levels and quality, effects of global warming, regional land subsidence, and the traditions of marsh burning. According to Haramis & Colona, this burn off is “a cultural tradition in the region now practiced on a broad scale by marsh managers.”

 . . . the little critters do not work alone to bring about this awful change. The factors are the same: changes in water levels and quality, effects of global warming, regional land subsidence, and the traditions of marsh burning . . .

 

From the air, the broad, vegetation-free paths these enormous rats create are clearly visible. Perhaps urged on by population density, though hardly notable ramblers, the rodents do travel from fairly wild areas into cultivated fields, doing terrific damage to dikes, ditches, and irrigation works there as well as destroying portions of crop. The penchant for roots these creatures exhibit represents an especially destructive trait, because it immediately kills the entire plant.

Making Fur Hats

Nutria have few, if any, natural enemies except for quite large carnivores—-pretty much this means alligators in these marshy areas—and human beings. Human beings, it should be clear, become predators based on an economic incentive. If a viable market for nutria products, flesh and fur, exists, the nutria population is subject to a controlling impact of commercial harvest.

When nutria were first brought to Louisiana, the original intent was to sell all parts of the prolific beast—that easy and fast replication itself being an asset, if the product was marketed. The fur is very high quality, and robust while still economical, the meat succulent and tasty (visions of nutria chili and nutria fricassee danced in the rancher’s head), and the residue had potential use in pet or livestock food. But several factors contrived to ruin this vision, and the businessmen lost interest and animals.

Louisiana has always had a strong relationship between residents and the outdoors. Changes in fashion, economic situations, and political feelings thus have an enormous impact on the state. Examples are easy to find, and they often have implications which reach far beyond the state.

fur coat
Fyodor Chaliapin, lined fur coat. Traditional use of fur – clothing.

Near the end of the 1800s, American women’s desire to don fancy hats decked with all manner of airy plumes and puffy feathers devastated aviaries in Louisiana and Florida. Once staggering flocks of egrets, roseate spoonbills and other beautiful feathered bipeds were eradicated, reduced to pounds of raw material packed carefully into crates and headed east on the new fangled rail system. The visibility of this frivolous slaughter, seemingly on every woman’s head on every city street, helped early activists pass wildlife regulatory apparatus.

The visibility of this frivolous slaughter, seemingly on every woman’s head on every city street, helped early activists pass wildlife regulatory apparatus . . .

 

On the other hand and ironically within a closely related commercial mechanism, the fashion world’s current clamor for expensive luxury goods made from exotic reptile skin helped support a multi-million dollar industry. Louisiana’s collect, hatch, and re-distribute program based on alligator eggs worked so well that the reptile is no longer on the endangered list.

The impulse to import nutria was based on the idea of harvesting the valuable pelt and perhaps the meat of the creature. And for a time, it worked.  In the 1960s and 1970s, over a million nutria were caught and sold, according to Jeff Marx of Wildlife and Fisheries. Now, as has been noted, the economic impact of the nutria is chiefly a negative one, with too many nutria disturbing the waterways, contributing to erosion of the coasts, and, in arable areas, meddling with the water control structures necessary for agriculture.

Louisiana’s Nutria Control Program

This overabundance of nutria, cute though they may be, precipitated Maryland’s government into suggesting a ten-year eradication program, based on recommendations outlined by British specialist L.M. Gosling, responsible for a similar nutria extermination plan in England. In the Maryland case, the suggestions of eradication in the early 1990s were met with plans to study the component of damage explicitly linked to nutria foraging activity.

According to Catherine Normand, a biologist with the Louisiana Department of Wildlife and Fisheries, “the major reason Louisiana had to develop a management program instead of an eradication program is that eradication is not feasible in our area. The nutria in Maryland were on a couple of thousand acres of isolated wetlands whereas we have more than 3.5 million acres of suitable nutria habitat just along coastal Louisiana and our marshes are connected to marshes in Texas and Mississippi, both of whom also have nutria.” As a result of that, she explains, if the animals were whipped out in one area, it would soon re-invest the depopulated habitat with new resident rodents.  Other differences and technical stumbling blocks to eradication exist, for example “Maryland’s area where the nutria were located was easily accessible by vehicle or boat. Not only are roads through coastal Louisiana relatively scant, but our flotant marsh (which literally means floating) is not easily accessible.”

As Normand points out, it’s not possible to use either boats for vehicles in this terrain, since it can’t support such weight yet is generally covered with vegetation. As she says, “the best way to reach those areas are with airboats, but those are not only expensive to own and maintain, but they are dangerous and can do a fair job of tearing up the marsh too if there is too much airboat traffic.” As a further complication a good deal of coastal Louisiana is private property, subject to landowner control, “it is they who get to decide what types of boats are allowed on their properties and insurance to allow airboats is really expensive. Finally, Maryland’s climate is not conducive for year-round survival for nutria because of their harsh winters where we have relatively mild winters. Even here, when we have a couple of weeks of freeze like we did last year, lots of nutria get frostbite and lose their tails, toes, and/or feet! But many more nutria survive our winters than could survive Maryland’s winters.” In the end, the space is vast, and the weather not bad enough.

At the turn of the twenty-first century, Louisiana opted to devote resources to a control program, to regulate nutria numbers, rather than attempt to eradicate the mammals. In the trapping season spanning November 2002-March 2003, Louisiana used federal funds to initiate a Nutria Control Program.  Doug Robinson, an Environmental Consultant with Coastal Environments of Baton Rouge (which had the contract to manage the program), made his way into the field every week to collect nutria tails from local trappers and to record the number and location of caught nutria.  The program set up six stations along the coastline, in public places easily accessible to trappers.

Before they could qualify, each trapper had to officially register with the program, obtain a valid trapping license, and provide documentation that they were trapping with the landowner’s permission.  Trappers were allowed to turn in tails no less than eight long, to discourage the trapping of baby nutria.  Trappers could either use traditional traps, or, if using shotguns, kill the nutria with steel pellets only.  Hunters were forbidden to use lead in shotguns so that other wildlife—particularly the Bald Eagle—that might feed on the dead nutria would not be poisoned.  Each trapper also had to follow specific guidelines for disposing of the body. Once the hunter/trapper qualified, he was paid $4.00 per tail (now $5).  Hunters averaged about 20,000 nutria per week, and some took home an income of $60,000 for four months of work.  According to Doug Robinson, most of the captured nutria came from the area starting at the mouth of the Atchafalaya River eastward to Cocodrie.

Some trappers sell only the tails; others skinned the nutria to sell its meat and fur.  One trapper we interviewed early in the program made an extra $7000 by selling fur. Not surprisingly, the market for nutria meat was still quite small, though there was hope it would grow . . . 

 

The Nutria Control Program was targeted to last five years, with the goal of collecting at least 400,000 tails per year.  Officials were even talking about the program lasting for 25 years–it’s still going.  In 2004 the program came very close to its goal by collecting 308,160 tails; year in and year out, the struggle continues – by 2017 state biologists monitoring the situation identified just short of 20,000 acres damaged by the critters. Some trappers sell only the tails; others skinned the nutria to sell its meat and fur.  One trapper we interviewed early in the program made an extra $7000 by selling fur. Not surprisingly, the market for nutria meat was still quite small, though there was hope it would grow.  Between seasons, the Department of Wildlife and Fisheries documents the impact of the trapping program, as well as areas of excessive damage done by the critters. For a number of reasons, these figures evidence subtle variations.

Trappers throughout South Louisiana may continue to turn to the natural environment in part to support a traditional way of life.  Many trappers learned the procedure from fathers and grandfathers. The Nutria Control Program offers a sort of stipend. With that and making use of as much of the carcass as possible, trappers can earn a reasonable, traditional living while helping to save the Louisiana marshlands.

 

Leave a Reply

Your email address will not be published. Required fields are marked *