Exotic Animal, Plant Species a Concern

By Tom Palmer
tom.palmer@theledger.com

Iwas heartened to read recently that the National Park Service is training beagles to track down Burmese pythons that are breeding in Everglades National Park.

The park covers 1.5 million acres, but at least they're doing more than many other land managers.

Much of the publicity about exotic species centers on plants because there are so many more of them, and they can alter the landscape unless they're controlled.

We know that because in some parts of Florida the landscape has already been altered when these plants weren't controlled.

Exotic animals can alter ecosystems in other ways.

The brown tree snake, which has single-handedly eliminated most of the native bird species on Guam, is every ecologist's nightmare invader.

An average Burmese python is 16 feet long. It can live 20 years. It eats small mammals, birds and other reptiles.

Like most of the 102 species of exotic animals found to have bred in the wild in Florida, these giant constrictors are the jetsam of the pet trade.

Pet stores market these and other creatures to people who have no idea how large the animals will become or what's involved in caring for them. Many disenchanted pet owners simply release the animals into the wild.

Meanwhile, there's the problem of the Nile monitor lizard.

This is another pet store horror story.

Like the Burmese python, the Nile monitor lizard is carnivorous.

Unlike the Burmese python, so far there is absolutely no eradication effort under way for these African predators.

Nile monitor lizards have not grabbed anyone's dog or cat yet, as far as anyone knows, though a biologist did find a pet goldfish in a dead lizard's stomach.

Some preliminary data from the examination of the stomachs of the lizards that have been caught reveals they have been keeping some of the other exotics under control, notably Cuban tree frogs and brown anoles, but some unidentified bird feathers in those lizards' stomachs are cause for concern.

These 7-foot lizards are, for the moment, found primarily in Cape Coral near Fort Myers. They live near fresh water. There's no evidence they are moving up the Caloosahatchee River to Lake Okeechobee yet, but the possibility makes some people nervous.

These lizards are elusive, with no natural controls and no one's sure how large a range they eventually could occupy.

The problem with Burmese pythons and Nile monitor lizards isn't just that they're large and carnivorous and thus potentially dangerous. Another problem is that they compete with native wildlife for food. If the exotics' numbers and range continue to increase, they could crowd out native species.

The two examples I mentioned above are just the land animals.

As in the plant world, there are exotic aquatic animals as well.

State wildlife officials have collected 86 species of exotic freshwater fish, 34 of which have bred. They range from tilapia, which are caught commercially, to armored catfish.

There are 31 exotic marine species as well.

Many of the exotic fish and shellfish came via aquaculture, releases of ship ballast water and multicultural food markets, according to state wildlife officials.

The cumulative effect is causing what some experts are terming "invasional meltdown."

By the way, it is illegal, though only a misdemeanor, to release any exotic animal into the wild. But as a practical matter, the regulation is difficult to enforce.

In the meantime, if you're traveling into the wilds in South Florida, watch where you step, make sure the vines you grab really are vines and keep your pet on a very short leash.

Tom Palmer can be reached at tom.palmer@theledger.com or 863-802-7535.