“Florida’s Invasive Invasion” is a perfect example of the second leading cause of what many scientists describe as the sixth mass extinction. According to the Center for Biological Diversity, the current rate of extinction is 1,000 times greater than the long-term historical pace. Additionally, the same organization suggests that we could lose 30 – 50% of earth’s current species by the mid-twenty-first century.
There is little doubt that the direct impact of man is the leading cause of that massive extinction rate. Deforestation is the most frequently referenced example of man’s immediate effect on it. Likewise, the enormous growth of the world’s population and demand for more urban development and forestry conversion into farmland is understandable. Perhaps less understandable is the unquenchable desire to exploit and profit from the reckless use of the world’s natural resources.
Another major cause of the current mass extinction, according to most scientists, is the displacement of invasive species. Over the world’s history, isolated ecosystems developed in a manner that worked cooperatively. Even though aggressive species continuously prey and live upon others, a natural balance seems to grow eventually. However, when one species is taken from one environment and recklessly placed into another, the established balance is disrupted.
Tropical South America and Latin America provide the United States with many agriculture imports. A large number of those imports are initially transported and unloaded in South Florida along with the invasive species that hitch rides. Additionally, many tropical pets escape or are released and find the tropical climate kind to their existence. Consequently, escaped invasive species find south Florida compatible with their needs where they quickly establish populations. This scenario has become a reoccurring story, which merits the title of this post, “Florida’s Invasive Invasion.”
Invasive Examples from Earlier Times and Other Places:
Unfortunately, globalization has facilitated the transportation of some exotic species into new ecosystems where they were disruptive and destructive. The Brown Tree Snake is a perfect example. During the final years of World War II, the increased military action in the pacific accidentally transported the snake from Australia/Indonesia to Guam. Unrestricted by natural predators and restraints, the Brown Tree Snake sowed havoc on the native bird and lizard population to the point that today they are both practically nonexistent.
Secondly, Spanish explorers introduced domestic hogs into America during the 1500s as a source of feed. Unfortunately, many of them eventually escaped and proved readily adaptable to wildlife. During the 1900s some well-intended sportsmen introduced the Eurasian Wild Boar into some regions of the United States for hunting purposes. Sadly, the wild boars proved to be a somewhat proficient escape artist and quickly added their genetic composition to the feral population that has been growing since the 1500s.
The hybrid strain of domestic, feral hogs and wild boar has proven to be a surprisingly resilient, fertile, aggressive, and a destructive addition to the native wildlife of America. Do note that the coverage of the feral hog population range was described as American and not just that of the United States. The reason is that the virulent population quickly stretched from the southern United States northward to Canada. Along the way, the hog population laid waste to numerous farm crops. Along with the farm crops, they destroyed large populations of snakes, lizards, salamanders, and turtles. Today the damage and cost control at the tusks of the hybrid swine are estimated to be around $1.5 billion annually.
Florida’s Invasive Invasion:
There is no better example of an invasive Invasion than the state of Florida. The Florida peninsula extends southward between the waters of the western Atlantic and the Eastern Gulf of Mexico into the tropical waters of the Caribbean Sea. Many exotic species find their way to South Florida by way of cargo ships, or sometimes as pets that owners have released. Many of the alien newcomers find themselves restricted to south Florida due to the geographical limits of the tropical climate. However, some find that despite having originated in a tropical environment that they can easily adjust to the temperate environment north of their initial location.
The impact of these invasive representatives differs significantly. Some seem to fit into the new environment with minimal disruptions. Others disrupt the natural balance that has found equilibrium over the previous centuries and millenniums. Unfortunately, there are a few that present a direct danger to the human race.
The following examples of invasive species represent only a few of the hundreds of alien forms of wildlife that has found their way into the United States by through Florida. However, they are representative of a group that presents a diversified impact that ranges from totally benign to environmentally disruptive to potentially dangerous to humans. Regardless of their effect, their numbers clearly illustrate that Florida’s invasive invasion can be a threat to native wildlife. Moreover, they can present a danger to human safety.
The Mediterranean House Gecko:
The Mediterranean House Gecko (Hemidactylus turcicus) first appeared in Key West early in the twentieth century perhaps aboard cargo ships or via the pet trade. Since then, they have slowly marched northward and across the southern United States. They appear to be a benign newcomer, but as they migrate northward with warming climate, the story remains unwritten.
As per the attached photograph, the lizards are primarily nocturnal, feed on insects near night-lights and are highly resistant to insecticides. Assisting their migration trends, they are quite fertile and fast breeders. If they do bite, it is ineffective, and they are not venomous.
The Cuban Tree Frog:
The Cuban treefrog, (Osteopilus septentrionalis) probably arrived in south Florida early in the twentieth century via cargo ships from Cuba and other Caribbean islands. Since their initial appearance, they have migrated to the northern parts of the state. Though they do feed on insects, they are cannibalistic and have been known to prey on several smaller native tree frogs. They can be gray, green, or brown and do have the ability to change colors. They have sticky toe pads that accommodate their climbing characteristics, and they frequently appear around night-lights. Their skin presents a slimy texture upon touch, which gives eye and nasal irritation upon contact. The population of native tree frogs has been reported to decline in their presence, and they are known to enter homes frequently.
The Green Iguana:
The Green Iguana (Iguana iguana) like many Floridian invasives migrated to Florida via the pet trade and cargo ships. They are large (up to 5.5 feet in length) and light green in color. They are also vegetarian, which makes them a nonexistent threat to Florida wildlife. Not surprisingly though, their largely vegetarian diet also includes several scarce plants in the south Florida area. Consequently, invasive species continue to demonstrate that they can be a threat to native wildlife and plants. Fortunately, they are not cold tolerant and their northward migration, even considering global warming, will be limited.
The Cane Toad:
The Cane Toad (Rhinella marina) was indigenous to northern South America and Latin America. However, because of a voracious appetite and their penchant for eating cane beetles that inhabit sugar cane fields, they have been intentionally relocated to areas that farm sugar cane. The cane toad wears the crown of being the largest member of the toad species with the larger females reaching lengths of better than five inches from snot to tail. The biggest problem that the toads present is the fact that they possess a significant toxin in the skin glands located immediately behind their eyes. The poison will readily kill small mammals that make oral contact. The cane toad has maintained its location in south Florida without too much northward migration.
The Burmese Python:
The Burmese python (Python bivittatus), imported into the United States via the pet trade, was first sighted in the Everglades area during 1980. After the turn of the twentieth century reproducing populations were reported in the same areas. Due to their large size (20 plus feet in length) and stealth habits, they are apex predators. Sadly the small mammalian populations in areas where they have established populations have been reduced from 80 to 100 percent. Their potential for migration is somewhat of a controversy. They do not tolerate cold weather well, but some scientists suggest that they have the potential to extend well beyond their current range. Additionally, global warming could extend that potential range.
The Lion Fish:
Perhaps there is no better example of the potentially intrusive and destructive nature of invasive species than the beautiful but caustic Lionfish (Genus Pterois). Released into native waters by aquarium owners, tired of the responsibility, the Lionfish proved to be a severe threat to the tropical water environment of the southeastern United States. While most of the smaller coral fish species are vegetarian, the Lionfish is carnivorous. This characteristic has joined hands with a devastating trend of ocean acidification to create havoc on the reef systems of the Caribbean and surrounding waters. The snapper and grouper population, already under attack from overfishing, found their fingerling population devastated by the voracious Lionfish appetite. The same fate fell on other reef friendly fish populations.
There is little doubt that one of the most dangerous animals in the world is the minute mosquito. Of course, the mosquito threat is due to the deadly mosquito-borne diseases that they transmit. The repercussions of these diseases account for millions of worldwide deaths annually. In 2015 malaria alone accounted for over 430,000 deaths. The detail that makes these statistics relevant is the fact that two of the more recent invasive species to find a home in the United States are mosquitos. More specifically, they are the Aedes, Anopheles, and Culex varieties of mosquitos. Fortunately, these well-established mosquito populations do not pose an epidemic threat at this point. The diseases associated with these mosquitos include Chikungunya, Zika virus, Dengue, West Nile virus, Malaria, and Yellow fever.
The invasive mosquitoes do demonstrate that species indigenous to tropical climates might adapt to and present a threat to more temperate regions. Many of the noted mosquito varieties quickly adapted to more temperate climates in the United States. Today many of these mosquitoes inhabit much of the southern one half of the United States.
The invasive species briefly described above represent some of the more commonly known examples, but they represent only a drop in the complete bucket of Florida’s invasive invasion.
For a while the more temperate climate of North Florida isolated it from South Florida’s invasive invasion.
Time always moves forward though, and recently the House Gecko and the Cuban Tree Frog ventured into the more temperate northern regions of the state. Not many people care about the House Gecko or the Cuban Tree Frog, but they represents a trend that warrants attention. If the Gecko and the Cuban Tree Frog venture northward, who will follow? Will the alien species threaten native species further north? How much further will the invasive mosquitoes venture? One thing should definitely not be forgotten: invasive species are the secondly leading cause of the sixth mass extinction.
Now if you happen to be interested in the topic of extinction, the Sixth Extinction by Elizabeth Kolbert should be a major read consideration. It will carry your understanding of this topic much further.
Thank you much for your time and attention
Content: This post was written by Michael Agner. Unless stated otherwise all unreferenced data can be found on the online Wikipedia Website.
Photographs: All of the post photographs have been altered in size to fit the post location. The use of any photograph taken by another photographer implies no endorsement for the context in which they are used. The author took all of the above pictures, or they are in the public domain, or they are legally reproduced under a Creative Commons license available as linked below:
Author and license under which they were reproduced:
Brown Tree Snake by Pavel Kirillov, Creative Commons License #2; Burmese Python by US Fish & Wildlife, Creative Commons License #2; Lion Fish by Alexander
Note: The use of any material in the public domain or under a Creative Commons License does not imply an endorsement of or for the material in which they are used.