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swamp rat

20 september 2017

Theodore Manno describes his own book Swamp Rat as "indefatigably researched," based on "every available primary research document involving nutria" (xvi, xv). Yet in a list of states with substantial nutria populations (13), he omits Texas! There may be some technicality about the list that I'm missing, or it may be a simple oversight. Elsewhere in Swamp Rat, Manno discusses Texan nutria in several places.

Not that I've ever seen nutria here. They are nocturnal and aquatic; I am terrestrial and I go to bed early. I also live far from the rain-ravaged Gulf Coast. But friends who live near water, even here in Dallas/Ft. Worth, report gardens gnawed by nutria. One of the most aggressive (at least in ecological terms) and successful of Texan invasive species, nutria have (Manno argues) reshaped the environment of the American South.

By the turn of the 21st century, "nutria were devouring Louisiana," says Manno (115). Striking new maps that show much of the state lost to the ocean are partly the work of nutria. By eating away the vegetation that holds wetlands in place, they return the Gulf Coast steadily to the sea. Climate change doesn't help: while raising the levels of sea and storm surge, it opens new territory northwards for the hungry, horny little critters. Nutria now infest coastal regions as far up as Delmarva (153-54), habitats that used to be too cold for them to winter over in.

At heart, nutria are neither rats nor ravening beasts. In their native South America, they are called coypu, and they destroy neither gardens nor wetlands. In this they would appear to be the obverse of beavers, who are busy but not destructive in North America, while laying waste to large tracts in South America. In each case, an industrious rodent, evolved to exploit but not destroy its home environment, has pillaged its new home.

Some theorize, says Manno, that alligators could have checked the rise of the nutria, if people hadn't spent so much of the 20th century trying to eradicate alligators. It stands to reason that the removal of a large predator would mean heady times for a prey species. But there's little factual support for this theory. Scientists know far less than one might think about the large dynamics of how animals share ecosystems: right down to whether alligators have much of a taste for nutria at all.

Attempts to foster that taste among humans have also failed to gain traction. Manno reprints a couple of gourmet nutria recipes, such as ragondin à l'orange, into which you probably prefer to substitute chicken, even if you could find some nutria to include.

Swamp Rat is at times padded (losing sight of its title animal for pages at a time while Manno talks about the history of the fur trade, or the geology of the Americas). In the last few sections, the book slips from academic prose into personal anecdote, becoming my bête noire, the interview-driven book. But I think that Manno's claims for his book hold true: it's the last word on nutria in the American south. However, the little guys are hardly going to keep still in the terms that Manno has framed for them.

Manno, Theodore G. Swamp Rat: The story of Dixie's nutria invasion. Jackson: University Press of Mississippi, 2017.