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In the never-ending debate over the impact of non-native species, there are invaders many of us have come to accept and even revere (the ringneck pheasant, Huns, chukars) and there are invaders that are almost universally reviled (the snakehead, kudzu, zebra mussels, Texas Longhorn fans).

But according to this interesting piece in Slate maybe invasive species, both “good” and “bad” really aren’t such a big deal, after all.

From the story:
_Tamarisk, a Eurasian shrub, is your classic invasive species–designated one of America’s “least wanted” plants by the National Parks Service. In recent decades, it has spread along Southwestern riverbanks, replacing native trees such as willows and cottonwoods…Measures to thwart them include burning, herbicides, and “tammy whacking” (physical removal sometimes done by freelance volunteers). A few years ago, the USDA let loose thousands of leaf-eating Asian beetles in order to sic them on tamarisks, which die from the defoliation…But these efforts to oust the intruder have encountered a glitch. It turns out that a charismatic endangered bird–the southwestern willow flycatcher–is known to nest in the offending shrubs. Last March, the Center for Biological Diversity sued the government, charging that indiscriminately killing tamarisks jeopardizes the flycatcher

These controversies highlight a broader debate within “invasion biology,” a field that emerged in the 1980s. Some scientists–such as Matthew Chew, Dov Sax , and Mark Davis–are challenging what they consider old prejudices about “alien” species. They point out the inevitability of change and the positive roles that non-natives can play in ecosystems, while describing eradication projects as often wasteful and even counterproductive._

It’s certainly a provocative point of view. At what point do “invaders” become so established that they’re essentially native? Take pheasants for example. You’d be hard-pressed to find a more popular gamebird than the ringneck pheasant. Millions of hunters pursue it. Dozens of states spend millions more managing for it. It has its own conservation group. It literally supports an entire industry. Huns? Introduced. Chukars? Introduced. Brown trout? Introduced. And beloved, all of them. The list goes on and on. The argument could certainly be made that there really isn’t such a thing as a completely “native” ecosystem at all any more and as such arguments for them are superfluous.

So is the potential loss of native species worth the potential gains of the newcomers? For example, would you support programs to boost dwindling native gamebird species like lesser prairie chickens even at the expense of more popular non-natives like pheasants? What are your favorite “invasive” species, and if given the chance would you trade them for a native?

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