Green anoles are native to the southeastern United States, where they are not invasive. Outside that native range, however, they are a serious invasive species. Introduced populations have established themselves in Hawaii, Japan, Guam, Taiwan, and several other Pacific islands, where they prey on native insects and have driven some endemic species to near extinction.
The confusion is understandable. In places like Florida, green anoles are the ones being displaced by another lizard, the invasive brown anole. But transport the green anole to an island ecosystem with no native lizard predators, and it becomes a destructive invader itself.
Native Range: The Southeastern US
The green anole (Anolis carolinensis) naturally occurs across the southeastern United States, from the Carolinas through Florida and westward into Texas. In this range, it fills an established ecological niche as a small, tree-dwelling insect eater and is not considered invasive. It’s the only anole species native to the US.
Ironically, green anoles are under pressure in much of their home territory. The brown anole, a separate species originally from Cuba and the Bahamas, has spread aggressively through Florida and other southern states. A University of Florida study found that when brown anoles move into an area, green anoles retreat upward, perching 17 times higher in the tree canopy than they normally would. Green anoles are most common in natural, wooded areas, while brown anoles thrive in urban environments with fewer trees. In cities across Florida, the brown anole has largely replaced the green anole as the lizard people see most often.
Where Green Anoles Are Invasive
Green anoles have been introduced, mostly through human transport, to a wide scattering of locations across the Pacific. Established populations exist in Hawaii, Guam, Taiwan, and multiple island groups in Japan, including the Ogasawara Islands and the Ryukyu Archipelago (Okinawa region). They were first recorded in Hawaii on the island of Oahu in 1950 and have since spread to at least six of the main Hawaiian islands.
Hawaii officially classifies the green anole as a restricted animal. It appears on the state’s restricted species list maintained by the Hawaii Department of Agriculture, meaning it cannot be legally imported or kept outside of approved research and exhibition settings.
Ecological Damage on Pacific Islands
The worst documented harm from invasive green anoles has occurred on the Ogasawara Islands, a remote volcanic chain about 1,000 kilometers south of Tokyo. These islands evolved in isolation, producing many species found nowhere else on Earth, and their native insects had no experience with a predator like the green anole.
After arriving on the islands, the anole populations went through a quiet lag phase, sitting at low numbers for years before exploding. On Chichi-jima Island, that lag lasted 14 years. On nearby Haha-jima, it was six years. Once populations expanded, the damage was rapid and severe. Green anoles feed on tree-dwelling, daytime-active insects, and their appetite decimated the islands’ unique fauna. An endemic butterfly species, the Ogasawara blue, was driven to near extinction. Five endemic dragonfly species suffered the same fate. Populations of cicadas, longhorn beetles, and small native bees also dropped sharply.
Similar concerns exist across other introduction sites. On islands in Hawaii, Guam, and Taiwan, green anoles prey on native animals and disrupt ecosystems that evolved without this kind of predation pressure. Island species are especially vulnerable because they tend to exist in small, isolated populations with no behavioral defenses against unfamiliar predators.
How Conservationists Are Fighting Back
Controlling green anoles on islands where they’ve established is difficult. The primary method used on the Ogasawara Islands involves fencing made from PTFE sheets, a slippery material (the same type of coating used on nonstick cookware) that anoles cannot climb. These barriers are placed around protected habitat zones to keep anoles from spreading into areas where endangered species still survive. Adhesive traps are also used to capture individuals.
Both methods have significant limitations. PTFE fencing can’t realistically be installed across roads or through towns, which leaves large gaps in coverage. Researchers have been exploring additional tools, including using sound as a deterrent. In experiments, green anoles froze for longer periods when exposed to the calls of red-tailed hawks and the alarm calls of a small bird species called the warbling white-eye. The anoles also physically moved away from speakers playing those sounds. This approach could potentially be combined with fencing to create more effective barriers, particularly in urban areas where physical fences aren’t practical.
Full eradication from any island has not been achieved. Once established, green anole populations are self-sustaining and difficult to remove entirely, which is why preventing new introductions remains the most effective strategy.
Green Anole vs. Brown Anole: Which One Is Invasive?
If you live in the southeastern US and are trying to figure out which backyard lizard is the invasive one, the short answer is: the brown anole. Green anoles are bright green (though they can temporarily turn brown), slender, and prefer trees and shrubs. Brown anoles are stockier, consistently brown with patterned markings, and are comfortable on the ground, on fences, and on walls.
Brown anoles compete with green anoles for food and territory, and they also eat green anole hatchlings. Their spread through Florida and neighboring states has significantly reduced green anole visibility at ground level, pushing the native species higher into the canopy. In natural, well-forested areas, green anoles still hold their own. But in developed landscapes with fewer tall trees, brown anoles dominate.
So the answer to “are green anoles invasive?” depends entirely on where you are. In the American Southeast, they belong. On Pacific islands, they are among the more damaging introduced reptiles, capable of quietly building populations for years before causing irreversible harm to species that exist nowhere else.