by Whit Gibbons

June 6, 2004

How would you like to find out that a 15-foot-long Burmese python was a permanent resident in your neighborhood? Add to this report that someone has found a clutch of 50 recently hatched python eggs, which means that pythons are breeding and that the juveniles have dispersed into the area. This exact scene has not been documented yet in suburban areas of south Florida, but the possibility exists. A recent book (The Exotic Amphibians and Reptiles of Florida, 2004, Krieger Publishing Company, Malabar, FL) by Walter E. Meshaka, Jr., Brian P. Butterfield, and J. Brian Hauge gives cause for the human residents of Florida to address the issue of introduced species of herpetofauna that have now become their new neighbors in the state.

The book provides an account of 40 species of reptiles and amphibians that are now believed to be established residents in the state. In other words, they have breeding populations that will continue to persist, often to the detriment of native species. Most of the exotic reptiles that now thrive in Florida are lizards and include species from Asia, Africa, India, and tropical America. Introduced species often do well in a new region because their population sizes are no longer controlled by natural predators. One of the ways that exotic species can eliminate native species is by outcompeting them for food, or in many cases just be eating them. For example, the Knight anole from Cuba will eat other lizards and reaches twice the size of most native lizard species.

Many of the exotic reptiles in Florida have been introduced as a consequence of the pet trade. Pet snakes are notorious for escaping from cages, even from professional herpetologists, and then getting out of a building. Pet trade facilities can be damaged or destroyed by high winds or trees, resulting in the escape of animals. For example, the book notes that the brown mabuya skink, a lizard from Southeast Asia, became noticeably more abundant around Coconut Grove in Dade County after Hurricane Andrew. But some releases have been intentional. For example, in 1985 people living around a golf course in Ft. Myers released Jamaican giant anoles, which now have an established colony.

One of the paradoxes of the invasive plant and animal problem is that intuitively a person might think that adding new species increases biodiversity. If biodiversity is a good thing, why would it not be good to add more species to the ones already present in a region? One of the simple explanations is that when an introduced species becomes dominant in an area, native species can decline in numbers and eventually disappear.

Although the animal pet trade is the ultimate source of most introduced exotic species, the majority of the specimens themselves are released into the environment by pet owners who are ordinary citizens. Getting a baby python that is only a couple of feet long may seem like a good idea until you notice that you have to feed it a full-grown chicken every couple of weeks. The size differential would be like getting a red setter puppy and realizing a few months later that it was the size of a cow. Not much smarter, but a lot bigger.

According to the book, the largest Burmese python found wild in Florida so far was less than 8 feet long, slightly smaller than the largest indigo snakes native to Florida. But these pythons are known to reach a length of 20 feet, which is more than twice the size of any snake native to the United States. With a warm climate and the availability of plenty of food, pythons should do well in south Florida. Young pythons will eat rats, mice, and small birds, and larger ones will fare well on possums, raccoons, dogs, cats, and larger birds. Burmese pythons can swim, climb trees, and creep through thick underbrush, so they should find plenty to eat. We may soon hear Floridians complaining that a resident species other than native alligators is eating pets and is perceived as a threat to children. Ironically, in contrast to alligators, which lived in the state long before people, pythons were brought to Florida by the people themselves.

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