Natural History: Anolis carolinensis (Green Anole)

     One particular herp species seen in abundance here in SC would be what is commonly known as the green anole (scientifically named: Anolis carolinensis). Upon arriving home one afternoon, I encountered this friendly green anole just casually warming itself up in the sun in front of my front door. Anolis carolinensis is quite common in the southeastern United States, but can also be found north through North Carolina, even more south in Florida (although it has been mostly replaced here by another species of anoles, Anolis sagrei), and even west in Texas. Being primarily arboreal and secondarily terrestrial animals, green anoles are commonly found in trees and bushes, but can also be found even in urban areas near homes, on fences, and even on the sides of buildings. Not surprising considering I found this green anole right outside my front door. Their green color helps them to blend in with trees, shrubs, and tall grass, but can also make them quite noticeable when they are against a white or tan background like in the pictures below, on my front porch.
      As mentioned above, the scales of the green anole which make up its skin can vary, but usually, green anoles can be brown, grey, or green in color. According to the source below, this is due to chromatophores in their skin, which are pretty cool. The chromatophores in their skin are xanthophores, melanophores, and cyanophores, and these chromatophores allow green anoles to change their scale colors in response to external stimuli in their environment. There are many factors that could cause a green anole to change its scale color, but some of the most common stimuli that cause this to occur would be temperature and excitation. If the temperature in its external environment gets too cold, the green anole can use its melanophores to turn a dark brown color, and if it gets excited by being active, or by competition with other conspecifics or even other animals, it can also change color too. Green anoles can also turn brown in color if they are under stress, which is really cool too. Judging from the green scale color of the anole I found and the fact that it was laying out in the sun, I would assume that it had warmed up pretty well. If the temperature was too cool for it, it may have been a darker brown color instead based on the information from the source.
      In male green anoles, pinkish red ventral dewlaps under the neck region are a common characteristic, but are usually not present in females. Dewlaps are used by male green anoles during courtship to attract the attention of female green anoles, but they can also be used in male-male competition over territory. Female green anoles, on the other hand, usually have a dorsal line that starts at the neck region and runs all the way down their back, ending right before the beginning of their tail. Green anoles generally have long tails, which surely help them balance their bodies as they climb since they are primarily arboreal lizards. Also, green anoles range in size from 4-8 in, males usually being a bit larger than females. The anole I came across at home seemed to be around 5 inches in size. The males being slightly larger and also the differences in color and pattern between males and females are good examples of sexual dimorphism in this species.  The green anole I found in front of my door appears to be a female because of the white characteristic line going down from its neck to its back just above the tail. It also did not appear to be a juvenile, but instead, appeared to be an adult.
     In terms of reproduction and development, most green anoles are polygynous, however, female green anoles don't usually go out looking for various mates. Female green anoles mate with different males when the males intrude into the female green anole's territory, according to the source below. Green anoles typically mate between April and August, since these months are when the temperature is warmer outside, and warmer temperatures enlarge reproductive structures in male and female green anoles. Females are only can mate during their ovulatory cycle, so breeding is dependent on this. Based on the number of ovulatory cycles a female has during the breeding season, she can lay between 6-9 eggs in 1 year's breeding season. Males have hemipenes, females have cloacas. Green anoles are interesting in that they exhibit examples of intrasexual and intersexual selection in terms of reproduction. Intrasexual selection occurs among green anoles based on territory ranges because the bigger a male's territory, the more females he has the chance of mating with. Usually, larger male green anoles have bigger territories because they can better protect their territory by fending off predators and intruders. Intersexual selection occurs among green anoles in that females can actually store sperm, and this is a reproductive advantage because it means that delayed fertilization can occur. When they are ready to lay their egg clutch(es), female green anoles look for moist soil to lay them in. After about 5-7 weeks, the eggs hatch and the juvenile green anoles become sexually mature around 8-9 months of age. This suggests that the life history of green anoles is direct development. Green anoles can live 2-8 years, based on predation, nutrition, access to resources, etc. Predators of green anoles include frogs, cats, dogs, large spiders (tarantulas), snakes, and some birds. However, to escape predators, green anoles can perform tail autotomy, which literally means that they voluntarily lose their tail so they can distract the predator with it as they run. They also can hide from predators in trees and in the grass and bushes with their green coloration.
     Green anoles are diurnal, and spend most of their day looking for food.  For food, green anoles usually consume anything smaller than them, such as insects, small spiders, flies, seeds, grain, and even some snails. Since their habitat is mainly arboreal, but also terrestrial and urban/suburban, they obviously have many places they can find food, however, most anoles typically stay within their own territory. Again, the larger the male is, the larger his territory. Females usually have smaller territories; mostly even within the range of a male's territory. In terms of behavior, green anoles are known for head-bobbing, neck-biting, and displaying dewlaps. Head-bobbing occurs when the anole is threatened, or when participating in courtship. It is a way for males and females to communicate their reproductive status during the breeding season also. Neck-biting occurs during mating by the male so that he can position himself over the female. The anole I came across seemed to have a friendly disposition, however, it was a good runner and was quick to escape once I tried to catch it. Green anoles are not a threat to humans because they are harmless lizards, not aggressive, and cannot deliver a bite tough enough to damage our skin.
     It seems that almost every field trip we have been on we have found green anoles because they are so common. However, I think they are still really cool herps. In fact, I think green anoles are fascinating enough to dedicate an entire blog post too. To me, they are adorable because of their green skin color and their friendliness. It is also awesome how they can do tail autotomy like glass lizards to distract and escape from predators. I really like green anoles, so I was happy to see this one in front of my door when I got home. It seemed friendly just like all the other anoles I had encountered before, yet it was startled when I walked up to the door and so it ran. They are fun to catch, hold, and observe before releasing them back where they were found (if you are fast enough to catch them, that is). The way that it was basking in the sun reminded me of the lecture about thermoregulation, and I could tell that it was really soaking up some sun.  Even if I wasn't able to catch this one to hold, I'm not so worried because with how common they are, I'm sure I will come across another one of these cool herps soon.

Works Cited: 
    Crawford, C. 2011. "Anolis carolinensis" (On-line), Animal Diversity Web. Accessed April 22, 2018 at http://animaldiversity.org/accounts/Anolis_carolinensis/

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