The small brown lizards darting across porches and fences in Florida and many other warm places are usually brown anoles, a species that isn’t from there at all. They come from Cuba and nearby Caribbean islands and arrived as accidental stowaways more than a century ago.1EDIS. Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) Their success has reshaped life for the native green anole, which has been pushed up into the treetops.
How to Recognize a Brown Anole
Brown anoles are usually brown, but they can lighten or darken their skin, ranging from brown to gray to black, and some have a reddish head.2EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) Their backs and sides often carry patterns of stripes, triangles, spots and dashes.3EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) Because the color shifts, pattern and shape are better clues than shade alone.
Females almost always have a light stripe running down the middle of the back and are more boldly patterned than males.4EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) Males can raise a smooth-edged crest along the neck, back and tail.5EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) The crest only shows when a male is excited, so not seeing one means little. They also have a throat fan, called a dewlap, that is reddish-orange bordered by yellow, which they flick out to announce themselves.6EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) The fans vary: some are a single color, some have a yellow edge, and some have yellow spots on the red.7PubMed Central. The brown anole dewlap revisited: do predation pressure, sexual selection, and species recognition shape among-population signal diversity?
A male’s display is easy to spot: he bobs his head and does push-ups on a fence or step while the throat fan pops out, then folds away. The show is aimed at rival males and at females nearby.
Compared with the green anole, the brown anole has a smaller body with relatively longer, stockier legs built for running and jumping.8PubMed. Assessment of the mass, length, center of mass, and principal moment of inertia of body segments in adult males of the brown anole (Anolis sagrei) and green, or carolina, anole (Anolis carolinensis) It typically stays within a couple of meters of the ground, on tree trunks, fences and walls.9Anole Annals. April 4, 2019 – Anole Annals
Green anoles can also turn brown. A green anole has a pink throat fan and a slimmer, longer head, and it tends to sit higher and on leaves, while browns stay lower on trunks. A back stripe or a bulky, short-headed look points to a brown anole.
Babies are trickier. Hatchling brown anoles are tiny, often under an inch of body length, and are brown from the start. A young green anole is usually green or shifts between green and brown, so a baby that stays brown and sits low is most likely a brown anole. Skinks and geckos are also small and brownish, but anoles have a slim body with a long tail, while skinks have smooth, shiny scales and short legs. Weigh pattern, head shape and perch height together, because stressed, cold or sleeping lizards can look unusually pale or dark.
Native Home in Cuba and the Bahamas
The brown anole is native to Cuba, the Bahamas and other West Indies islands.10EDIS. Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) The species arose in Cuba roughly 4 to 5 million years ago, with western and eastern Cuban groups later spreading across the northern Caribbean.11PubMed. Phylogeographic and phenotypic outcomes of brown anole colonization across the Caribbean provide insight into the beginning stages of an adaptive radiation It evolved in warm, open, sunny island habitats, and yards, parking lots and gardens resemble those open spaces.
At home, the brown anole eats spiders.12Shorelines. From the Field: Lizards, Spiders and Mangroves With fewer spiders, flying and plant-eating insects can increase, so plants can suffer more insect damage where anoles are abundant.13Shorelines. From the Field: Lizards, Spiders and Mangroves
How Brown Anoles Got to Florida and Beyond
The brown anole was Florida’s first documented introduced reptile, arriving in the late 1800s.14EDIS. Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) It likely came accidentally in cargo shipped from Cuba.15EDIS. Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei)
It wasn’t a single event. Genetic studies show brown anoles were introduced to Florida at least eight times from different parts of their native range.16EDIS. Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei)
A lizard hitchhikes easily. Adults hide in plant branches and leaves, and eggs sit unseen in the soil of potted plants, so nursery stock and landscaping shipments carry both.
Most introduced anole populations came from more than one source population, so lizards from different native islands interbred in their new homes.17PubMed. Multiple sources, admixture, and genetic variation in introduced anolis lizard populations Many introduced populations ended up with more genetic variety than native ones.18PubMed. Genetic variation increases during biological invasion by a Cuban lizard That helps an invader: variety gives natural selection more to work with.
Florida is the likely source of brown anoles now found in places such as Hawaii and Taiwan.19EDIS. Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) The species has spread across parts of the U.S., the Caribbean and Central America, and has been introduced in Asia.20Diversity. Borderless Lizards: Unveiling Overlooked Records and the Expanding Invasion of Anolis sagrei in Ecuador Public sightings have recorded it in Israel, Canada and northern South America.21Diversity. Borderless Lizards: Unveiling Overlooked Records and the Expanding Invasion of Anolis sagrei in Ecuador In Ecuador it has spread along the coast and into an Amazon province, favored by urban areas.22BioInvasions Records. Updated distribution of the brown anole in continental Ecuador: a case of urban spaces favoring the establishment of an opportunistic exotic species
Why Brown Anoles Spread So Well
Females lay one or two eggs every week or two through the whole breeding season, so a female lays about 15 to 18 eggs a season.23Animal Diversity Web. Anolis sagrei She can do this because she alternates between her right and left ovaries.24Animal Diversity Web. Anolis sagrei Eggs go into soft, moist soil, which greenhouses and garden plots provide.25St. Charles Park District. What Are Brown Anoles and Where Did They Come From? Since they’re scattered one at a time, if one egg is eaten or crushed, others elsewhere still survive.
Breeding has also sped up where they’re introduced. Introduced females lay eggs at shorter intervals than native females, and their eggs hatch more quickly.26Biological Journal of the Linnean Society. Life histories and invasions: accelerated laying rate and incubation time in an invasive lizard, Anolis sagrei Populations can grow and spread faster in new areas as a result.
Brown anoles eat many kinds of insects and spiders and sometimes smaller anoles.27Anole Annals. prey – Anole Annals They have been seen tackling very large prey and even caterpillars and centipedes that can be toxic.28Anole Annals. prey – Anole Annals A species that needs one specific food can live only where that food exists, but brown anoles use whatever small animals a yard offers, from ants and flies to spiders. Eating smaller anoles, including young of their own kind and green anoles, turns a competitor into a food source.
Climate is no wall either. Northern introduced brown anoles handle cold better and lose less water than southern ones.29PubMed. Physiological variation among invasive populations of the brown anole (Anolis sagrei) That matters because winter chills and dry spells are what normally stop warm-climate lizards from moving north.
Cities suit them too. Their eggs tolerate heat about 2°C better than those of a shade-loving relative, suiting hot, open city spots.30PubMed. Thermal tolerance in the urban heat island: thermal sensitivity varies ontogenetically and differs between embryos of two sympatric ectotherms
What Brown Anoles Do to Green Anoles
Where brown anoles move in, green anoles perch about 17 times higher in the canopy.31News. UF Study: Where brown anoles invade, native green anoles reach new heights That shift can begin within a few months.32Science. Florida Lizards Evolve Rapidly, Within 15 Years and 20 Generations Over about 15 years and 20 generations, green anoles evolved larger toe pads with more sticky scales.33Science. Florida Lizards Evolve Rapidly, Within 15 Years and 20 Generations
The two species overlap in diet and in the sunny, low perches they like, so they compete for food and space. Browns also eat smaller anoles, so greens that stay low risk being eaten, while those living higher avoid both competition and predation.
Toe pads are the sticky scales under an anole’s toes that let it cling to smooth surfaces. Higher in the trees, branches are narrower and leaves smoother, so lizards with bigger, stickier pads grip better and are less likely to fall. Those lizards survived and bred more, their young inherited the larger pads, and the average shifted over generations.
Even with the move up, green anoles are declining while brown anoles thrive.34News. UF Study: Where brown anoles invade, native green anoles reach new heights Habitat loss from urbanization adds to the pressure.35News. UF Study: Where brown anoles invade, native green anoles reach new heights If you have both species, you’ll likely see browns on the fence and lower trunk and greens up in shrubs and the canopy, less often.
Brown anoles also carry a widespread invasive parasite in Florida, a worm-like parasite that lives in the lungs.36Ichthyology & Herpetology. Native and Nonindigenous Anurans and Lizards Are Intermediate Hosts for the Invasive Pentastome Parasite Raillietiella orientalis in Florida It infects green anoles and native frogs and toads too.37Ichthyology & Herpetology. Native and Nonindigenous Anurans and Lizards Are Intermediate Hosts for the Invasive Pentastome Parasite Raillietiella orientalis in Florida Brown anoles may help this parasite spread quickly to new areas.38Ichthyology & Herpetology. Native and Nonindigenous Anurans and Lizards Are Intermediate Hosts for the Invasive Pentastome Parasite Raillietiella orientalis in Florida
Can You Get Rid of Brown Anoles
Brown anoles are so widespread in Florida that there is little chance of eradicating them.39EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) No approved eradication method exists, and on Maui they are beyond local control resources.40Maui Invasive Species Committee. Brown Anole – Maui Invasive Species Committee They’re small, fast and well camouflaged, and they live across huge areas including private yards, so no one can search every hiding place. Still, efforts can slow further spread, especially in Florida’s Panhandle and beyond.41EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei)
Taiwan paid over US$350,000 in rewards for caught anoles from 2009 to 2017.42Anole Annals. Taiwan Tries a New Tack to Get Rid of Invasive Festive Anoles The payments did not bring the population under control.43Anole Annals. Taiwan Tries a New Tack to Get Rid of Invasive Festive Anoles Officials switched to containment focused on plant nurseries, checking shipments for lizards and eggs.44Anole Annals. Taiwan Tries a New Tack to Get Rid of Invasive Festive Anoles Nurseries are the main route by which anoles reach new places, which is why containment can work where removal does not.
Hawaii lists all anoles as injurious wildlife, banning release or moving them to new islands.45Maui Invasive Species Committee. Brown Anole – Maui Invasive Species Committee Hand-capture and humane euthanasia can reduce numbers around a yard, though they’re hard to catch.46EDIS (University of Florida). Florida’s Introduced Reptiles: Brown Anole (Anolis sagrei) Check the soil and leaves of new nursery plants before moving them to a new area, and never release a pet anole outdoors.
For a homeowner, removing a few won’t stop neighbors’ lizards from moving in, and they pose no danger to people or pets. Reducing clutter and moist mulch near the house does cut egg sites.
You can help by reporting sightings. Photos on apps like iNaturalist track their spread, and such records have revealed new populations in other countries.