New Study on Color Change In Green Anoles

Green anoles can change from green to brown. Occasionally, they do it only part way. Photo from http://www.floridagardener.com/img/critters/Greenanole.jpg

Widely, if inaccurately, known as the American chameleon, Anolis carolinensis is renowned for its ability to change color from a sparkling emerald to a deep brown. Surprisingly, we don’t really know what factors determine whether a particular lizard chooses to be green or brown at a particular time.

Here’s what I had to say about it in Lizards in an Evolutionary Tree (pp. 279-281; I’ve omitted most references here):

“In theory, we might expect green anoles to match their background, turning green when in vegetation and brown when against a woody surface. Although widely believed, this idea is not strongly supported (reviewed in Jenssen et al., Herp. Monographs, 1995). In one study, male A. carolinensis mismatched the surface upon which they sat (green on brown substrate or vice versa) more often than would be expected by chance (Jenssen et al., 1995; but see Medvin [Animal Behaviour, 1990] for an opposite result). Indeed, males of green species often adopt a bright green coloration when in the survey posture, although a darker appearance would almost surely be more cryptic against a woody background; this tendency suggests the possibility that skin color is being used to make the lizards more, rather than less, conspicuous (e.g.,  Macedonia’s work on A. conspersus and Trivers’ on mating A. garmani).”

You’d think we’d have a better idea of what’s going on with color in as common and obvious a species as A. carolinensis, but even Jenssen et al.’s very detailed field behavioral studies only began to suggest some ideas. Now, a recent study of A. carolinensis on the Japanese island of Chichi-Jima has tried to take this further. By noting the color of 169 anoles encountered in the field, Yabuta and Suzuki-Watanable tried to look for correlates of color. As with previous work, they found no evidence that the anoles were matching their background (incidentally, this is true of real chameleons as well—they apparently don’t change color to blend in). Other data, however, suggested a possible role for green as a social signal. First, adult males were more often green than other animals and, second, a weak association existed between perch height and proportion of adult males that were green. By contrast, no association was found between air temperature and color, thus working against the hypothesis that dark color was used in thermoregulation.

Clearly, there is a lot yet to be learned about color change in A. carolinensis, not to mention the many other—as yet unstudied—green anoles. One wouldn’t think such work would be all that difficult, at least the field component  as an initial starting point. This study is a nice example of how one might start such a study, simply by going out and seeing under what conditions  anoles are green versus brown, and how that varies between sexes and size classes.

One last quote for LIAET, because it’s tangentially relevant:

“Color change is under hormonal control in anoles and often occurs in social encounters   (reviewed in Greenberg [2002, 2003]; the physical mechanism by which color change is produced is reviewed in Cooper and Greenberg [1992]). For example, almost half of the instances in which A. carolinensis males changed from green to brown occurred in the context of aggressive encounters (see also Trivers [1976] on A. garmani). Many of these occurred as males were approaching the boundary of their territory, but before an opponent was visible (e.g., the male which owned the adjacent territory was on the other side of a tree trunk), which suggests that the male in some sense anticipated an agonistic encounter (Jenssen et al., 1995). In general, dark color is a response to heightened stress, although a variety of other factors—including predation attempts, temperature, and light levels—also affect color in A. carolinensis (reviewed in Jenssen et al., 1995; Greenberg, 2003). During male-male interactions, lizards will change color frequently; by the end of the encounter, the winner is usually green and the loser brown (Greenberg, 2003).”

 

About Jonathan Losos

Professor and Curator of Herpetology at the Museum of Comparative Zoology at Harvard University. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

24 thoughts on “New Study on Color Change In Green Anoles

  1. A green Carolina anolis I saw yesterday turned very dark brown upon being caught and played with by my cat. (Yes, it survived unharmed, by the age-old strategy of not moving until the cat grew bored.)

  2. My anole turns brown a lot. It’s probably stressed a lot because it’s been abused (ex: thrown around, dropped, shaking it, etc.) by children in the past. In taking good care of her now that those kids don’t have her. (my anole was given to me)

  3. I have adopted two anoles for a class project and plan to do a color changing experiment with them. I will be testing to see if different background colors will affect their color while they hunt for crickets. As of right now, the background on the walls of their aquarium are white and there is a fake green plant, a perching branch, and wood chips in the aquarium. They are usually green when they are on the walls and more of a brown while on the wood chips. I have noticed that when it is feeding time they turn brown before they eat and then back to green after they eat.

      1. I found out that before feeding time my green anole clover is green so that when she is hunting and after hunting her color turns brown

    1. Hi Kyle,
      Along the lines of what Jonathan said, would you consider taking photographs and crafting a few paragraphs about what you did? I think our readers would be interested to find out. Also, I don’t know what year you are in at school, but we’re always looking for ways to include anoles in classroom projects. So please feel free to share. You can contact me at mmunoz@oeb.harvard.edu

      Best of luck,
      Martha

  4. Today morning I found such a creature in Dar es salaam, Tanzania, East Africa. I was eagerly searching what type of creature it is and upon a search finally reached at your article. thanks for sharing.

  5. I was sitting and enjoying the warmth of the sun today watching an anole walking along the top of the fence. It found a nice place in the sun to rest and then changed from a bright green to a dark brown. It sat for a while then blew up its red throut a few times turned back to green and walked on down the fence. I wish I had a video of it. It was very intresting and the first time I saw one do the color change.

  6. Wow nice to know that i have a one living in my tree I found it today it stayed green and chilled I got nervouse. Because my dog cookie loves catchin lizards and I helped it to my Awacate tree it’s soo nice and preety !!

  7. I have a male on my deck of my house in coastal NC that changes color when it changes location. In the bushes (0ff my deck) it is green sometimes olive green. When it comes out onto the rail of the deck which is stained brown it changes to brown in a minute or so.

    There is a wooden retaining wall that is gray and stained with algae to a fairly dark green and this Anole changes to olive green when he is hanging out there. When he jumps back onto the deck he changes to brown. When he is moving in the direction of the retaining wall he displays the wattle thing and is changing his color to olive.

    When he is displaying on the deck he stays brown until he heads for the bush and then changes to the lighter green when he gets into the bush.

    The windows looking onto my deck area are mirrored so the lizard can’t see me observing. He is about 7 inches long and this is his first time here, that I have seen. There is a much smaller (2 1/2″) Anole that stays brown with darker spots on the backbone. I think it is female because it doesn’t display. There is also a blue tailed Skink about 7 inches that comes onto the deck to sun itself. The skink has been here for several years.

  8. I just got my green anoles (3 still very young) and they all are a bit nervous, but curious. I have a heat pad and day light, so I have it go temp wise, and the humidity is up at 83% , but apparently, these little guys don’t like the sun lamp. I infered this when I turned it on in the morning, and the only one awake instantly started to turn brown when I turned the light on. I wonder if he’s scared of the light? The others aren’t awake yet due to the fact that it is 7:30 am, but the sun is already up. Im getting 3 others in another terrarium, and I dont want them in any stress. So, any suggestions?

    1. Try a lower wattage bulb it might be too hot. Some heat pads can get too hot also. I’m no expert ,but i had to do alot of research when i found a green anole on a pallet of supplies at work. Which would’nt have been that strange except for that it was December and i live in Ohio.

  9. I just bought my first green anole today. When I first spotted her, she was a bright green on one of the fake trees in the terrarium. Now, she has taken to climbing up to the humidity gauge on her tank, and turns such a dark brown that she’s almost a black to match the color of the gauge. She was carried in a wet brown paper towel on the way home and turned that color as well. My anole’s camouflage instinct seems to be fine

  10. We just adopted an anole from my son’s school who had them in the classroom for a science unit. Most things that I have read indicate that turning brown is a sign they are stressed, and that being handled stresses them. She basks from fake green plants in the aquarium and is often brown, but when I take her out and hold her for a few minutes she turns green again. Does this mean she is not getting enough heat? I have a heat lamp on the tank all day and night. I’m just confused why she would frequently be brown.

  11. Green my German sherpard chased lizardsgr around our fence.Now a green lizards Was on my kitchen couter.Looked at me n said I live here.Put him out.Guess they had babies found 2 more put them out. I WAS BAKING BROW
    NIES. PUT MY HAND ON STOVE HA NDLE N A BABY LIZARF CRAWLED OUT ON HANDL?E SAID I MOVEF N YOUR STOVE BIT YOU COOK GOOD.1ST TIME THEY MOVEF N GUEDS LIKE INSIDE DOGS BETTER THAN OUTSIDE.Is this normal lizard behavior
    ?

  12. I have two green anoles, I am not entirely sure if one is male and the other is female but they began to move their heads and bodies in a push up manner and one was flaring it’s neck the other went away and turned brown but I would hate for them to get into an aggressive territorial fight. What should I do?

  13. Honestly, my Anole loves being handled. She is brown when she is in the tank with no interaction and is green when we carry her around when we take walks or just hang out

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