Why Is South Florida Overrun with Green Iguanas?

Green iguanas can really thrive in ecosystems where they don't belong -- and that can be a real problem. Learn more about these large reptiles in today's episode of BrainStuff, based on this article: https://animals.howstuffworks.com/animal-facts/iguana.htm

Learn more about your ad-choices at https://www.iheartpodcastnetwork.com

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of I Heart Radio,
Hey brain Stuff, Lauren Bogabam. Here, something perhaps even weirder
than usual is happening in Florida. I grew up there,
so I can make that joke. In case you hadn't heard.
Iguanas are all but overrunning the Sunshine State, and we're

(00:22):
talking about big lizards. They're thriving there because of South
Florida's subtropical climate and the lack of natural predators, while
there are lots of non native saurians trudging through the
area more like the forked tongued denial monitor. The creature
we're specifically alluding to here is the green iguana, taxonomical
name Iguana iguana. It ranks among the largest lizards in

(00:44):
the Western Hemisphere. Adult females can be five feet that's
one and a half meters in length, while the biggest
males may reach an impressive seven feet or two meters
long from nose to tail tip. An average weight is
around fifteen pounds or four and a half kilos, though
heavier specimens weighing seventeen pounds or seven and a half
kilos or more have been documented, and despite its proportions,

(01:07):
The species has long been a staple in the exotic
pet trade and unfortunately a victim of abandonment when they
get too big. That's helped these critters spread far beyond
their natural range, causing property damage and competition with native wildlife.
By and large, green iguanas are herbivores. They may eat
insects or dead meat on occasion, but it's fruits and

(01:30):
leaves that make up the bulk of their diet. Though too,
green iguanas vegetation isn't just a food source. This is
a tree loving animal that, given its druthers, spends most
of its time basking in forest canopies. Scaling branches comes
easily to the lizards. With their long fingers and hooked claws.
These guys are first rate climbers. Of course, you don't

(01:54):
spend a lifetime in the treetops without taking the occasional spill.
Green iguanas have been known to withstand fift foot that's
fifteen meter falls and walk away uninjured. This species is
also perfectly at home in the water. I'm much like alligators.
The animals swim by undulating their tails from side to side.
Frightened iguana might also choose to seek refuge below the

(02:16):
surface if a predator is lurking about. We are not
used to thinking of non avian reptiles as sociable, but
yet the green iguana is somewhat gregarious. Hatchlings are born
in underground nests, sometimes in the vicinity of crocodilians. Baby
iguanas stick together, forming social groups with their siblings for
mutual protection. Such units can last for months, during which

(02:40):
time the young lizards groom one another and sleep side
by side or in piles iguana. Iguana is sexually dimorphic,
with females looking visibly different from their masculine counterparts. Both
sexes have dew laps, that's folds of loose skin that
dangle below the neck. These are proportionately larger in males

(03:01):
and an important communication tool. Come breeding season, a male
iguana will defend a huge territory and ideally mate with
a number of females, whom he'll guard for an extended period.
To scare off rivals, males aggressively bob their heads up
and down, dew laps flapping all the while. While we're here,

(03:21):
let's discuss coloration and not all green iguanas are literally
green They also come in shades of brown, blue, red,
and gray, and males often turn orange or bronze ish
when it's time to court potential mates. Today, the green
iguana remains one of the United states most popular reptilian pets,
but that doesn't mean they're easy to care for. Sharing

(03:43):
your life with an iguana can be deeply rewarding, but
you should know what you're getting into beforehand. Hatchlings will
be about eight inches that's twenty centimes long, and might
fare nicely in a tabletop terrarium, but experienced hobbyists recommend
that adult enclosures measure at least six ft high by
x feet wide and twelve feet long in meters that's

(04:03):
about two by two by three and a half. Before
it was artificially introduced to new environments, the green iguana
was restricted to Central and South America, along with a
smattering of islands in the Eastern Pacific and Caribbean. Back
in at least fifteen of the lizards suddenly appeared on
a Caribbean island with no pre existing green iguana population.

(04:25):
The scientists think the reptiles road floating mats of uprooted
vegetation that drifted out to sea in the wake of
Hurricanes Luis and Maryland. Presumably the raft bound castaways traveled
all the way from Guadaloupe, some two hundred miles or
three kilometers to the south. Unfortunately, when the local climate
is favorable, iguana iguana can thrive in places where it

(04:48):
doesn't belong. In nineteen sixty six, the first scientific report
on invasive iguanas in South Florida was published. It seems
likely that many individuals reached the Florida and Peninsula by
going away on boats and in shipping crates. America's booming
pet industry sure didn't help alone. More than one point

(05:08):
one four million iguanas were imported into the United States.
Although it's possible to buy captive bread specimens nowadays, a
wild cop babies are still being shipped to the US
and mass It's unclear how many free ranging green iguanas
are loose in South Florida. More than seven thousand iguana
sidings have been recorded by the University of Georgia's Early

(05:29):
Detection and Distribution Mapping system. Since most of those after,
a large percentage of the lizards now running about the
state probably descend from escaped or unwanted pets. Ecologists warned
that the herbivores are devouring important native plants, including a
coastal vine that the endangered Miami blue butterfly lava feed on.

(05:52):
Various flowers may also be at risk. A green iguanas
have been turning private gardens into buffets, and to add
insult to injury, the Szard's leave feces on patios, boat decks,
and other surfaces, and metaling iguanas are doing a number
on Florida's infrastructure too, and just one iguana caused a
ten minute power outage when it trespassed on a key

(06:13):
West Electrical facility in two thousand eighteen, and West Palm
Beach is facing one point eight million dollars in damages
incurred after tunneling iguanas messed up a local dam. In
twenty nineteen, the Florida Fish and Wildlife Conservation Commission made
headlines by encouraging homeowners to humanely kill green iguanas on
their property whenever possible. One doesn't need a license or

(06:37):
permit to hunt them on public lands. The several worried
citizens have also called for Floridians to eat more iguana meat,
which is a traditional protein in parts of the Caribbean.
Being cold blooded, iguanas have been unable to establish viable
populations in northern recesses of the state. Even down south,
the lizards occasionally fall victim to chili conditions. The animals

(07:00):
go into paralysis when the thermometer hits forty four degrees
fahrenheit or six point six celsius, which doesn't happen often
in South Florida but did in January another cold snap
in killed off a large part of the iguana population. However,
once the weather warms again, most adult iguanas can recover
from this kind of temporary incapacitation. You do will to

(07:23):
keep your distance. In the meantime, a stirring iguana can
really bite. Today's episode is based on the article South
Florida is overrun with green Iguanas on housetuffworks dot com,
written by Mark Mancini. Brain Stuff is production of iHeart
Radio in partnership with how stuff works dot Com and
is produced by Tyler Clang. Four more podcasts from my

(07:46):
heart Radio visit the iHeart Radio app, Apple Podcasts, or
wherever you listen to your favorite shows.