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Tracking Missouri's Exotics

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Published on: Jan. 2, 2000

Last revision: Nov. 4, 2010

accidental, but it was probably intentional. After all, purple loosestrife is a beautiful flowering plant that has been used medicinally for many years.

The problem is that purple loosestrife spreads quickly and in a short time will completely dominate ponds, lake edges, stream banks and ditches in pastures, fields and roadsides, wiping out native plants in the process. The Conservation Department has been spraying purple loosestrife with herbicide annually since the 1980s. The process has to be repeated every year because seeds are left behind after spraying.

We are all potential vectors for the spread of exotics in Missouri. A child might bring home a frog or crayfish only to have his or her mother insist that the animal be released immediately. If the release point isn't the same as where the animal was captured, the release-especially if the critter is pregnant-might disrupt the habitat.

We can't completely guard against accidental introductions. Gypsy moths can hitch a ride on the web recliner we rested in outside our campsite in Michigan, for example, or a weed seed might stick to the lining of our hunting jacket in North Dakota and fall to the ground in the Bootheel.

The few things we can do, however, may make a huge difference in our quality of life and may prevent the disappearance of some of our treasured native species. Knowing how disruptive even a single introduction of a nonnative species to Missouri can be, we recommend these few simple precautions.

  • Inspect and clean equipment that travels from state to state. You may have a stowaway hidden on your boat or your trailer. Some creature or plant seed could even hitch a ride under your bicycle seat.
  • Either release leftover bait back where it came from or save it for another trip. If you bought your bait, killing leftover bait is probably the safest way to get rid of it.
  • Tell your child that critter they want to keep will be happiest and healthiest where it belongs and may cause big problems elsewhere.

 Take Them Home

  • Introduced species don't have to come from far away. The St. Francis River crayfish, for example, is indigenous to one, relatively small river drainage in the entire world. Not only is it extremely threatened by introductions of other crayfish species into its narrow habitat, but if you caught a St. Francis River crayfish and released it in another drainage it could cause problems in the new environment.
  • An organism may be native to a particular region, state, watershed, lake or pond. Anytime you take a creature from where it lives and release it somewhere else you may be contributing to irreversible damage to a natural system. In one case, a school principal suggested releasing crayfish she had brought back from Louisiana into a local stream, unaware of the threats the release would have on local crayfish.
  • Kids and adults love to learn about nature, but the common and seemingly harmless practice of collecting organisms for study, then releasing them anywhere other than where you collected them can have serious consequences. Think of animals living at a specific address. When you've learned all you can about them and want to release them, make sure you take them home.

Problem Introductions

Other exotic species in Missouri and their associated problems include:

  • House sparrows. These compete with other cavity nesters, such as bluebirds, and are a nuisance because they nest and roost in buildings.
  • Gypsy moths. Large populations of these voracious moths are moving across the country. They have completely defoliated forests in some northern and eastern states, and small pockets of them have already been found in Missouri.
  • Elm disease. This killer of native elms has changed the character of our forests and has defoliated city parks.
  • Asiatic clams. These "imported" clams are taking over Missouri streams, threatening to replace our rich variety of colorful native clams with a single species.

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