🐬 At a glance
- Scientific name
- Iguana iguana
- Status in Florida
- Invasive & unprotected; native to Central & South America and the Caribbean
- Size
- Up to 5+ ft nose to tail tip; large males near 17 lb
- Where to spot them
- Seawalls, canal banks & riprap along the Marco River and residential canals
- Diet
- Mostly plants, flowers & fruit
- Rule
- Never feed them — it works against local management efforts
What are those lizards on the seawalls?
Halfway down the Marco River, someone in the bow usually spots one first: a big, prehistoric-looking lizard flattened out on a rock in full sun, head cocked toward the boat like it’s daring you to get closer. That’s a green iguana, and no, you’re not imagining it — they’re a real, established part of the local scenery along Marco Island’s seawalls, canal banks and riprap. Adults run long, sometimes five feet from snout to tail tip, with a whip-thin tail that makes up more than half that length and a jagged crest of spines running down the back like a miniature dragon. Color varies with age, temperature and mood: hatchlings are bright grass-green, while older males often fade to a dull grey-green or take on a rusty orange cast during breeding season. They’re strong swimmers and will drop straight off a seawall into the canal and vanish underwater if a boat gets too close, which is honestly half the fun of spotting one.
Are green iguanas native to Marco Island?
No — and this is the part that surprises most guests. Green iguanas are native to Central America, South America and parts of the Caribbean, not Florida. The lizards sunning themselves along Marco Island’s canals today are descendants of escaped and released pet iguanas, part of a wave of exotic reptiles that took hold in South Florida’s subtropical climate starting in the 1960s and 70s and never left. They found the region’s mild winters, abundant landscaping and seawall-lined canals nearly identical to home, and the population has been expanding ever since. If you’re trying to sort out what’s native and what isn’t while you’re out here, our Wildlife Guide and its Naples & Marco Island wildlife checklist break down which animals actually belong on this stretch of the Gulf coast versus which ones, like the iguana, hitched a ride in through the pet trade.
| Animal | Native or invasive | Where you’ll see it | Quick ID |
|---|---|---|---|
| Green iguana | Invasive (Central & South America) | Seawalls, canal banks, riprap, mangrove edges | Long whip tail, spiny ridge, up to 5+ ft |
| Brown anole | Invasive (Cuba & Bahamas) | Landscaping, fences, tree trunks — everywhere | Small (5 to 8 in), does push-ups, orange throat fan |
| American alligator | Native | Freshwater canals, Rookery Bay, inland sloughs | Broad snout, eyes riding just above the waterline |
| Gopher tortoise | Native | Sandy uplands & dune scrub, not open water | Slow-moving, deep burrows, high domed shell |
Why the city actively manages them
Iguanas aren’t just a curiosity out here — they’re a maintenance headache for the people who own the seawalls and canal banks they call home. Female iguanas dig burrows into soft banks and berms to lay their eggs, typically in spring and early summer, and a single stretch of shoreline can end up honeycombed with tunnels after a few seasons of repeat nesting. Those burrows undermine the soil behind seawalls, and enough of them in one place can genuinely destabilize the structure — an expensive problem on an island built almost entirely around canals like the ones along the Marco River. That’s why the city and local property owners actively manage the population rather than letting it grow unchecked; it’s less about the lizards being scary and more about protecting the infrastructure that keeps Marco Island’s waterfront intact. If you notice a cluster of fist-sized holes low on a canal bank on your next trip out, now you know why.
What happens when it gets cold?
Green iguanas are cold-blooded, and Marco Island’s subtropical climate keeps them active almost year-round — part of why they’ve done so well here. But on the rare winter cold front that drags nighttime lows down into the 40s or lower, iguanas go torpid. Their muscles stop responding properly, their grip on a tree branch fails, and they can lose their hold and fall to the ground, stiff and seemingly lifeless. It sounds alarming, and it’s become a bit of a Florida legend — local news and the National Weather Service both issue iguana cold-weather warnings during hard freezes further north in South Florida. The good news is that a torpid iguana usually isn’t dead; once the sun comes back out and temperatures climb, most simply thaw out, shake it off and go right back to basking like nothing happened. Marco Island’s winters are typically mild enough that true iguana-dropping cold snaps are uncommon here, but it’s a real phenomenon in the wider region and one our captains get asked about often.
Should you feed them?
No — never feed an iguana you spot on Marco Island, and that goes for every animal you’ll see out here, from dolphins to pelicans to the lizards on the seawall. Feeding invasive iguanas trains them to associate people, docks and homes with an easy meal, which only encourages them to congregate in higher numbers right where they cause the most damage to seawalls and landscaping. It also works directly against the management efforts already underway to keep the population in check. Green iguanas are mostly herbivorous grazers — flowers, leaves, fruit and the occasional hibiscus bloom off someone’s dock make up the bulk of their diet — so they don’t need a handout to get by. Our captains follow the same rule with every animal on the water, wild dolphins included: we point, we narrate, we let you get the photo, and we never toss food to wildlife of any kind. It’s a small thing that keeps the whole ecosystem healthier for the animals that do belong here.
Where you’ll spot them on a tour
Most guests meet their first Marco Island iguana on the ride out, not the destination. As we idle down the Marco River past the seawalls and canal-front homes on the way to open water, keep an eye on the riprap and dock pilings — sunny mornings are prime basking time, and it’s common to spot one or two stretched out mid-canal before we ever clear the pass. It’s never a guarantee — iguanas are shy, quick to slide into the water, and less visible after a cold snap or on overcast days — but on a warm, sunny run it’s one of those strange-but-true bits of local color our captains love pointing out, right alongside the ospreys, manatees and dolphins you came for. It’s a fitting preview for the rest of the trip: the water around Marco Island is full of surprises, native and otherwise, and spotting the ones that don’t belong here is half the fun of a morning on a dolphin & wildlife tour. Bring a camera — between the iguanas on the way out and the wildlife once we’re clear of the canals, you’ll have plenty to shoot.