Welcome to my zone 9a habitat garden near Houston, Texas.

Monday, July 8, 2013

The invasion of the decimators

(Cross-posted from Backyard Birder.)

There are many challenges facing the environment around the country, indeed around the world, these days, but among the most deadly and seemingly intractable of these are the invasives.

Invasives are plants or animals from someplace else in the world that have been brought to our shores, sometimes deliberately, sometimes by accident, and released or escaped here. Often these plants or animals find a hospitable habitat with none of the natural enemies or controls which they encountered in their native land. The predictable result is that their population explodes. They compete with native species and sometimes overcome them, even wiping them out.

In the island nation of New Zealand, for example, where non-native rats and stoats have become entrenched, they haveexterminated at least 19 bird species.    

In the United States, one of the most famous invasives is theHouse Sparrow, which was deliberately introduced in New York in the 19th century. It quickly spread and began to compete with native hole-nesting birds like Eastern Bluebirds and Tree Sparrows, contributing to a decline in these as well as other species before human intervention began to give the natives a fighting chance.

In the 20th and 21st centuries, with the globalization of the economy and the ease of tourism between countries, the rate of introduction of invasives exploded. No state in the country has suffered more from this phenomenon than Florida.

From walking catfish, Asian swamp eels, Cuban tree frogs, monkeys, iguanas, and, most famously, Burmese pythons, the state's ecology  is overrun by invasives. Indeed, the pythons have been so successful in the Everglades that they have virtually wiped out the small mammal population there. This, of course, has disastrous and long-term effects on the other predators in the area that normally depend on these mammals for food.

Even the alligators there have had trouble holding their own against the pythons. Bodies of the native reptiles have been found in the stomachs of big pythons that have been captured and killed.

As if all of this were not enough, Florida is now battling another invasive - giant African land snails, sometimes called GALS. These snails can get up to 8 inches long. Each snail contains both male and female reproductive organs and every mated snail lays about 1200 eggs a year. As of June 22, Florida state officials reported that they had captured and killed more than 124,000 of the snails in the area around Miami.

These snails pose a major threat to gardens and to farmers' crops because they will feed on and destroy at least 500 different types of plants. But it's not just plants that they gobble. They will also chew on plaster and stucco, thus causing damage to homes. And, one other thing: They also carry a parasitic nematode that can lead to meningitis in humans. Unbelievably, these critters were deliberately smuggled into the country by a religious cult which uses them in their "healing ritual."

Florida is battling its invasives with all available resources, but in all too many instances it seems to be losing the battle. There is always the chance that many of these species will be able to spread to other hospitable habitats, especially in adjoining states along the Gulf of Mexico. As the climate changes, becoming warmer, the possibility of some of the species being able to move into even more areas of  the country only increases, all of which could prove to be devastating for our native plants and animals. The decimation of species which Florida has experienced could become more widespread.

It is a nightmare scenario, one that desperately needs a solution but for which no real workable solution seems in sight.


  1. Yes, I am a member of many wildlife conservation groups and have read about the problem of invasives and how Florida is particularly inundated. This post mentions rising temperatures, however the rise in temperature has stopped for the past five years (scientists are looking at this stall in rising temperatures now)so that may no longer be a factor. Invasives remain a serious problem so thanks for alerting people.

    1. I refer you to Skeptical Science for an answer as to whether global warming has stopped in the last five years. In fact, it hasn't.


  2. The list seems endless. In Florida, Brazilian Pepper trees take over native habitat and lionfish are now decimating reef fish in the Keys. Closer to home, Bermuda grass takes over everything in its way and Bastard Cabbage crowds out native wildflowers.

    1. Too right, the list is endless! New ones seem to be added daily. As for Bermuda grass, my nemesis, I am engaged in daily hand to root combat with it.