Since the dawn of time the transmigration of species has been constant. Whether drifting on ocean currents, floating on winds across vast distances, or being assisted by various other means, organisms large and small have found ways to pioneer new areas. Nature is never static. Any one moment in natural history is just that, a moment, never to be repeated again. It's a vibrantly dynamic system.
Humans have certainly aided and abetted a vast array of organisms in their movements. Since the earliest people walked the earth we've stirred the pot, so to speak. Something as simple as unwittingly carrying a seed stuck in a sandal might introduce a plant to a whole new environment. Trade in the early days brought exotic plants and animals to a widening world; a world sometimes receptive to its new guest, sometimes hostile.
Once we began sailing the seas things sped up considerably. Diseases, once confined to certain areas of the known world, were now unleashed on populations of peoples with little defense. Exotic plants and animals were introduced to all corners of the world. Islands, those isolated and biologically insulated spots of land, were irreversibly affected by such critters as domestic swine, goats and rats which quickly (and in most cases, permanently) established themselves in their new environment.
Enter the railroad, the automobile, and the airplane. Today the introduction of exotic species happens overnight in all corners of the reachable globe, even right at home. The first example of spotted knapweed (an NDSU publication calls it "an aggressive, introduced weed species that rapidly invades pasture, rangeland and fallow land and causes a serious decline in forage and crop production") in Cass County was found along railroad tracks in West Fargo. It's not hard to imagine a single seed hopping a ride on a rail car in Montana before finally being blown off here.
Sometimes we even mix things up on purpose. Results run the gamut from success to abject failure. European starlings and house sparrows were intentionally brought over from the Old World. Both species quickly expanded, thrived on their new continent, and continue to meddle with our native array of avifauna. The common carp was another idea gone bad. First introduced to America in 1831 as a food fish, this Eurasian species has become the bane of nearly every freshwater system in the country.
Leafy spurge was thought to have arrived here in sacks of grass seed in the early 19th century. It is one of the major noxious weed species in many states, including North Dakota. In an ironic twist, we've come to biologically combat leafy spurge with yet another exotic complex of species - flea beetles. And so it goes.
Targets for hunters and fisherman have long been on the introduction menu as a means to enliven the sports. Rainbow trout, muskie, and Chinook salmon are a few examples of apparent success with exotics in North Dakota. All offer a fishing experience unlike another.
The history of bighorn sheep in North Dakota serves up another dish of irony. Lewis and Clark encountered the animal in 1804. Years later the animal - dubbed "Audubon's" bighorn sheep - was extirpated leaving a gaping hole in our native landscape. "California" bighorn sheep (from British Columbia) were reintroduced to the Badlands in 1956 where its success is evident today. Originally it was thought the two subspecies were distinct, leaving us with an arguably "exotic" introduction. Recent evidence, however, belies that belief. It's very likely both are merely populations of the nominal Rocky Mountain bighorn sheep.
The ring-necked pheasant might be the poster child for successful game introduction. The Asian bird was released in America beginning in the middle of the 19th century. Where it has thrived, an entire hunting culture has grown up around it. It could reasonably be argued that certain counties in North Dakota rely on the bird for a large percentage of their taxable income.
We will continue to witness new organisms colonize places where they hadn't been - some intentional, some not. We'll struggle with some (swine flu, Norway rat, Eurasian milfoil) and enjoy the benefits of others (gray partridge, sugar beet, Black Hills spruce). For those longing for the "way it used to be," forget it. The biological landscape is a continually moving target. Our grandchildren will very likely deal with species we've never even heard of.
Corliss is a West Fargo resident, avid birder, and ND Game and Fish volunteer instructor. He serves as a corporate pilot for Forum Communications. Corliss maintains an outdoors blog at areavoices.com/kcorliss. firstname.lastname@example.org.