But, like an alligator submerged except for its eyeballs and nostrils, there’s more below the surface of this story. And that’s where some weighty concerns lie.

To begin with, the alligators’ owner(s) might not have researched, or been able to handle, the requirements, natural behaviors and growth potential before acquiring what is a high-maintenance exotic species. Then, once released, the alligators faced certain death in Chicago’s cold winters. (In addition, the reptile expert who rescued the animals pointed out that people posed more of a threat to the on-the-loose gators than the other way around.)

Finally—and this is the big-picture problem—dumping unwanted non-native pets into the local river or lake or forest preserve or national park can wreak ecosystem havoc. And it has.

Burmese pythons, green anacondas and Nile monitors are among the large predatory reptiles that pet owners have intentionally or accidentally released into the Florida Everglades. Alligators, which came off the federal endangered species list 23 years ago, are now competing—and not necessarily successfully—for habitat and prey on their home turf with these giant, aggressive non-natives which, unchecked by any predators, are breeding and spreading.

Lionfish, native to the coral reefs of the Indo-Pacific, have spread with unprecedented speed throughout most of the Caribbean and up the eastern coast of the United States. Scientists believe the first few lionfish in the Atlantic escaped from a Florida home aquarium when a beachfront house was hit by Hurricane Andrew in 1992. Since then, however, ongoing releases of these beautiful but venomous fish by hobbyists mainly account for the species’ rapid expansion along the Atlantic coast, with sightings as far north as Long Island Sound. Voracious eaters, lionfish have savaged native reef fish populations through both direct predation and competition for food. They also pose a significant threat to fishermen and divers. Biologists believe that the widely established invasives might be controlled eventually but will never be eradicated from their unnatural range.

Snakeheads are a family of freshwater fishes from Africa and Asia that can breathe air, move across wet land, consume massive quantities of prey, grow to 3 feet long and produce thousands of young up to five times a year. Escaped or released snakeheads quickly became such an ecological threat that it is illegal to keep them as pets in all 50 states. But it’s a little late. They are permanently established in the Potomac River, and have been seen in waters from Maine to California (including one captured right here in Burnham Harbor in 2004) as well as in Hawaii.

Aggressively invasive non-native species—those that outcompete and out-reproduce the locals—have many avenues into our natural areas. Zebra and quagga mussels arrived in the Great Lakes in ocean freighters’ ballast water. Floods carried Asian bighead and silver carp out of their ponds on southern fish farms and into the Mississippi River and its tributaries such as the Illinois River. Their threat to the Great Lakes is an international concern. Sea lampreys got a pass into the upper Great Lakes when the Welland Canal opened, skirting Niagara Falls to complete the inland water route from the Atlantic Ocean. It took the lampreys a mere 20 years to wipe out the already overfished native lake trout in Lake Michigan. Common carp, a European relative of the bigheads, were intentionally introduced into the Great Lakes as a food fish—that nobody wanted to eat. Unfished, adaptable and prolific, they thrived, crowding out the natives and tearing up shoreline habitat for fishes and waterfowl alike in their search for food.

The list goes on and on. Today, more than 180 invasive non-native species of plants and animals call the Great Lakes home, and the number grows each year.

Alligators probably won’t be added to that list. Historically, the species hasn’t ranged north of Arkansas. But we can help to stem the tide of other non-native invasions through responsible pet ownership. And who doesn’t want to be a responsible pet owner? So, learn everything you can about the care of an unusual pet before acquiring one. Know that you can provide for its special dietary and environmental needs. And never release unwanted fishes, amphibians, reptiles, or any other pets into the wild. Never. If you no longer want an exotic animal, contact your veterinarian, the local pet store, or a hobbyist group such as the Chicago Herpetological Society to find it a new home. It’s one more way you can make a difference for the Great Lakes. In fact, make it your pledge to Keep the Lakes Great.

--posted by Karen Furnweger, web editor