Monday, November 29, 2021

Invaders Among Us

River otters (seen here), raccoons, possum, deer and other animals are on the python menu. In some areas of South Florida populations are down as much as 90%! PHOTOS BY BOB MCCONVILLE

River otters (seen here), raccoons, possum, deer and other animals are on the python menu. In some areas of South Florida populations are down as much as 90%! PHOTOS BY BOB MCCONVILLE

Bob McConville
Master Naturalist

Let’s take a short trip back in time. Florida has stabilized from thousands of years of climatic turmoil. Sea levels have risen close to what we know in the present day, and the weather has settled as well. It is the year 3,000 B.C. and we are native to this land. We do not farm, but depend on the land and the sea to provide our food. It is plentiful.

Fish, rays, mollusks, turtles and much more sea life fulfill our dietary needs, with just a small dependence on land animals as well. As we enjoy our families and our simple life, we marvel at the number of birds around us. Herons and egrets nearly darken the skies as they take flight. Animal life is abundant in the Marco Island area.

Somehow, magically, we natives of the land are transported 5,000 years to the present day. Almost immediately shock is experienced! Where are the birds?

Just a few dot the sky! Where are the fish that we used to eat and why are there so few? What are these strange plants and animals among us!

Other humans have changed our lands. They have brought with them species of animals and fish not native to our region. There has been a change, and not necessarily for the better.

Not all of these so called “exotic” species present a threat to the naturally occurring fish and animals in our area, but many do. More than 500 wildlife and fish nonnative species have been observed in our state.

Exotic species are those living outside of captivity, but did not historically occur in Florida. Many are “introduced,” which means they have been brought here by humans. Some of the more common ones, like armadillos, certain foxes and coyotes not only came in with humans, but they expanded their natural range as the need for food and individual territories became necessary.

Some of these have not had an ecological impact on native fish and animals, but some definitely have. Let’s take a look at some of the more common ones.

With a native range of India, the Malay Peninsula, lower China and some East Indies islands, the Burmese python is one of the largest snakes in the world. They have been seen in Everglades National Park since the 1980’s. It is thought that many were house pets that grew too large and were released in South Florida. It is also thought that a python breeding facility destroyed by Hurricane Andrew in the early 1990’s is also responsible for the introduction of these monsters. Just recently, one was caught in Shark Valley, along U.S. 41 and west of Miami that measured 16 feet 4 inches, the second largest Burmese to be seen in South Florida. They prey on a variety of mammals and birds and they

Burmese pythons are here to stay. This non-native snake has established a presence in southern Florida.

Burmese pythons are here to stay. This non-native snake has established a presence in southern Florida.

are consuming a large amount of our native species. Areas with an increase in python population are seeing a decrease in raccoons, possum, herons and egrets by 90%.

As food supply diminishes, it is likely that this species will move westward. Two pythons have been seen on Marco Island and, just last December, one measuring 16 feet was caught on the Isle of Capri. Several marsh rabbits were equipped with radio transmitting collars and, after a short period of time, many transmitters were located…inside of several pythons!

Tegus are native to South America. Likely escaped pets, or intentionally released into the wild, these lizards can reach 4 feet in length. Found primarily in Miami-Dade County, they have also been seen in Lee County.

Their diet includes eggs, insects, fruits and vegetables, and they will also be attracted to dog food and cat food. They look very much like a large salamander or lizard, but their extremely sharp teeth can be very harmful.

One of the largest dangers to our native fish, and also to our habitat, is the lionfish. Although it is unknown how they first arrived in Florida waters, the initial sighting was in 1985 on the east coast near Dania Beach. In the last 30 years these invaders have spread like wildfire!

They eat our native fish, and that reduction in population can have profound effects on our reef structure. Many area fish play important ecological roles that keep algae in check on the reefs. If these fish disappear, the algae can grow. If the algae grows too fast and too much, our reef structure could be subject to negative change.

Lionfish can reach maturity in less than 1 year. The females release masses of 12,000 to 15,000 eggs and can create two such masses at one time. They can spawn every 4 days in warmer climate. Since the initial sighting in 1985, Lionfish are now being located as far north as Rhode Island, all along the Gulf Coast as far west as Texas, and south into the Venezuelan coast.

There is a well-known portrait depicting an actor as an American Indian named Iron Eyes Cody. This portrait shows this man crying in the “Keep America Beautiful” public service ads in the early 1970’s.

As an area native in 3,000 B.C. there would be no reason to cry. Transported to present day, we might all shed a tear when we realize how humans have changed this environment. It is not all bad, but some events cannot be undone. Sadly, I weep for our future.



Bob is the owner of Stepping Stone Ecotours and a Naturalist on board The Dolphin Explorer, a dolphin survey program. He is a member of the Society for Ethical Ecotourism. Bob loves his wife very much!




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