What comes to mind when you hear the word "alien"? Does your mind conjure up images of little green men or merciless invaders? For me it's actually the second image that comes to my mind. In most cases that is exactly what alien or invasive species are; they are merciless invaders. In almost every case, these plant, fungi, or animal species compete with or kill our natural species.
It isn't a problem only in our country. Invasive species are a global issue. In my yard alone, we commonly see at least 5 species; multiflora rose, Asiatic daylily, house sparrows, and European starlings. These few species are but the tip of the iceberg. The previously mentioned species are just a small sampling of the alien species out there. Some species make the news while others we don't hear of at all. Species that we've heard of include zebra mussels, pythons, Asiatic long-horn beetles, big-headed carp, and kudzu. Each plant or animal that enters a foreign place can carry with it, it's own problems.
An alien species often is an escapee or is released on purpose. Mute Swans were brought over to make our parks feel more like Europe. Sadly, these birds are aggressive and in some instances push native waterfowl away from prime nesting places. Kudzu was a plant that was introduced into the United States to help deal with erosion. It worked the plant took over and covers up other plants. Zebra mussels were accidently released from the ballast tanks of a ship. The nutria was being raised for its fur when a hurricane hit freeing these critters from their cages. The list could go on and on. They are a very serious environmental issue and in some cases they are an economical problem as well. I want to move to another subject. The subject that I want to hit on next is pets; released pets.
Released pets put into wild will eventually do two things. They will thrive for a season perhaps. If they can find a mate, they might even breed. Escaped or released pets can cause problems in the ecosystems. Pets like Burmese pythons and tarantulas now are living in Florida. There have been alligators removed from Indiana waterways. Want an idea of what invasive species are currently living in our great country?
Well, I don't have an answer for you on the exact numbers. I'm guessing it's well above 550 species total. In the Great lakes alone there are around 150? species. There are more than 50,000 species of invasive species. in our country. These numbers are growing every year. This growth only imperils more of our native species. Some of the invaders will be limited to the warmer states while others might be found in the other areas. Any way you look at it, invasive species create a disruption to our ecosystems. They also take our tax dollars to control them.
I mentioned earlier in this piece that invasive species compete aggressively for resources with our native species and that they can disrupt our native ecosystems. Consider the following if you will, the lionfish that I've mentioned in a previous post is living in the warm Atlantic ocean waters around Florida. These fish are not only predatory but they are also venomous. How do these invasive species become a problem? Well, these species enter an area where either they lack natural predators or have an abundance of plants in some cases they do both. An absence of predators and an abundant food supply leads to a population explosion. This explosion leads to all sorts of problems. Below is a link that talks about invasive species in North America.