Costly Turf Wars in the Wild Kingdom
/Originally published in 2014. Amended 2018.
Florida wildlife and habitats were something to behold for my family from Pennsylvania when we arrived here in the 1970s. Exotic animals and plants we had only seen in books or on television dominated the landscape. It took no time for my brothers and me to develop skills for getting our hands on any wild thing that crawled, swam, slithered or flew, and lizards were abundant most anywhere on dry land.
Also known as the Carolina anole, it’s the lizard we saw most in the 70s. As a native species, they’re meant to inhabit Florida and other states including the Carolinas. These animals also play important roles in the grand scheme by keeping insect populations in check. They also provide valuable sustenance for predators including birds and larger reptiles such as snakes and North American alligators.
Over the years, we encountered less of them around Florida, and looking back, like a pot of boiling water, they gradually vanished. While on assignment in Beaufort, North Carolina in 2013, my brother Brooks and I crossed paths with them again. The interaction caused us to reminisce about their rarity in our adopted home state of Florida compared to a few decades prior.
It was a few months later while observing a reptilian mating ritual outside my home when I recalled that conversation in North Carolina. This display of rough sex in the wild by the now invasive brown anole lizard species reminded me of the precarious balancing act playing out within Florida and around the United States. Hard fought and costly turf wars are being waged on multiple fronts in the wild kingdom. Battles between even the smallest of creatures are part of a much larger conflict taking place.
Brown anoles were first observed in the Florida Keys in 1887. Their arrival in cargo shipments through major seaports in South Florida during the 1940s helped set up their territory in most urban areas south of Gainesville by 1980. This timeline confirms my observations of abundant green anole populations in the 1970s and their subsequent decline.
MOTHER NATURE PLAYS REFEREE
The adult male browns have a competitive superiority over the same food sources the greens rely upon. They also eat green anole eggs and their vulnerable young. The more aggressive and dominating brown displaced greens forcing them to adapt from their primary ground territory to an elevated existence in the branches of bushes and trees. This dramatic reduction in their native range and resulting drops in population caused the powers of natural selection and the mechanism of evolution to kick in. Green anoles adapted their hunting methods and diet to shift from slower moving ground dwellers like beetles and roaches to more agile flying insects.
Evolved green anole foot. Photo: Yoel Stuart
Compelling physical changes to the anatomy of green anoles were also documented in a study conducted by Yoel Stuart. A postdoctoral biologist at the University of Texas, Stuart says their feet are now bigger and stickier. In 2014, his published findings with a handful of other researchers state this evolution took place in just 20 generations of the lizard or about 15 human years. The study states greens forced to live in trees and bushes feature a larger pad on their fourth toe compared to their ground-dwelling relatives not affected by invasive browns. This toe pad also exhibits more scales and thousands of microscopic hairs that enable it to better cling to surfaces; a feature that enhances climbing and clinging ability.
But they’re just lizards. Who cares? What’s the big deal? Brown anoles are part of a much bigger problem and they have plenty of company. Over 500 non-native fish and wildlife species and 1180 non-native, exotic or alien plant species are documented in the Sunshine State, according to the Florida Fish and Wildlife Conservation Commission (FWC). ‘Non-native’, ‘alien’ or ‘exotic’ are interchangeable terms describing species that may or may not become ‘invasive’ or ‘naturalized’, once presented to an environment. If that sounds confusing, it is. Let’s break it down the real problem.
INVASIVE SPECIES DEFINED
Contrary to a popular belief in some circles including most news and media outlets, non-native, alien and exotic species don’t always qualify as invasive; a term used far too loosely given important distinctions. The United States Department of Agriculture (USDA) defines an invasive species this way.
An invasive species is one that is:
1) non-native (or alien) to the ecosystem under consideration and
2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health.
Invasive species can be plants, animals, and other organisms (e.g., microbes). Human actions are the primary means of invasive species introductions.
Some non-native species arrived in Florida by natural range expansions. For example, cattle egrets, a bird species, native to Africa and Asia, flew across the Atlantic Ocean in the 1950s. The FWC classifies these species as not native to a location but that have adapted and established a stable or expanding population. They deem these ‘naturalized’. The coyote and red fox migrated to Florida through natural range expansions from other states so they also fall into this category. Brown anole lizards were introduced via human activity and are harmful to the native green anole and so are a legitimate invasive.
Other human-introduced invasive examples include the Cuban tree frog. Arriving in 1931 through cargo packing materials, it spread to Florida’s natural habitats by the 1970s. It is an effective predator of native tree frogs. Burmese pythons became invasive headliners after their prolific expansion throughout the Everglades. As a large, efficient and resilient predator, it has wreaked havoc on many native species populations. Birds and other reptiles including turtles, alligators, and their eggs have become a staple of the python’s diet. According to the United States Department of Agriculture, feral swine are descendants of escaped or released pigs. Also known as; wild boar, wild hog, razorback, piney woods rooter, and Russian or Eurasian boar, they are a dangerous, destructive, invasive species.
Burmese python consuming a North American alligator in the Florida Everglades. Photo: OJATRO.com
In virtually every case of destructive invasive wildlife, human intervention is the cause through error, carelessness or the unintended consequence of modern travel and transportation methods. The fact is, some animals have no business being here. Campaigns to eradicate or at least control those species’ advance while avoiding further intrusion from others must continue. If my opinion doesn’t make the case, consider the following statement by U.S. Fish and Wildlife Service.
“The negative consequences of invasive species are far-reaching, costing the United States billions of dollars in damages every year. Compounding the problem is that these harmful invaders spread at astonishing rates. Invasive species cost the United States more than $120 billion in damages every year.”
Thanks for reading. {sp}
