Opheodrys aestivus, commonly known as the rough green snake, is a nonvenomous North American colubrid. It is sometimes called grass snake or green grass snake, but these names are more commonly applied to the smooth green snake (Opheodrys vernalis). The European colubrid called grass snake (Natrix natrix) is not closely related. The rough green snake is docile, often allowing close approach by humans, and seldom bites. Even when bites occur, they have no venom and are harmless.
The rough green snake (Opheodrys aestivus) is bright green above and has a yellowish belly, affording it excellent camouflage in green vegetation and making them difficult to see in the wild even though they are relatively common in their habitat. It has keeled dorsal scales, which are arranged in 17 rows at mid-body. It grows up to 116frac=4NaNfrac=4 in total length (including tail)[1] and is very thin.
The specific name, aestivus, is Latin for "summer" in reference to the species' green dorsal color.[2] The generic name, Opheodrys, is derived from Greek ophios, meaning "serpent", and drys, "tree".
The rough green snake ranges throughout the Southeastern United States, from Florida, north to coastal Maine, Indiana, and west to Central Texas. The snake is commonly found in the Piedmont and Atlantic coastal plain, but is not found in the higher elevations of the Appalachian Mountains. It is also found in northeastern Mexico, including the state of Tamaulipas and eastern Nuevo León.
The preferred habitat of O. aestivus is moist meadows and woodlands, often near water. It is highly arboreal, and prefers a narrow arboreal microhabitat of dense brush in edge situations. This microhabitat is found in a variety of habitats, such as lakeshores, streambanks, upland ravine.[3] Frequently found climbing in low vegetation, and is also a good swimmer. However, it is often found on the ground as well. Unlike many snakes, it is largely diurnal. At night it is found coiled in the branches of trees. Preference is given to perches based upon distance from the shoreline, height of branches, and thickness of the individual branch.[4]
The diet of O. aestivus consists mostly of insects and other terrestrial arthropods, but some snails and tree frogs are eaten as well. This snake is not a constrictor; most prey are grabbed and simply swallowed alive. O. aestivus has been shown to rely heavily on visual cues for prey detection and to prefer living prey items.[5] As foraging activity increases, thetongue evolves greater elongation and deeper forking, and the abundance of chemoreceptors increases in the vomeronasal organs, the chemosenory responsiveness is adjusted to match diet and orthopterans constitute 16.9% and all arthropods about 98% of dietary volume of the rough green snake.[6] Rough green snakes exhibit greater chemosensory investigation of chemical cues from their insect prey than from representatives of several other taxa because of the linked importance of insects to their diet.They are able to live away from standing water by sucking droplets of dew from leaves.[7]
Predators of the rough green snake include birds and other snakes, such as the eastern racer (Coluber constrictor) and the eastern king snake (Lampropeltis getula). They can also be infected by parasites including the Cryptosporidium species.[8] The rough green snake also does not exhibit any predator-resistance capabilities besides fleeing however they rely heavily on their camouflage.[9] They often undergo a lot of stress due to human presence.
The male rough green snake reaches sexual maturity at an age of 2 around 245 mm long. The females of the rough green snake reach sexual maturity around 1–2 years of age, or when they reach between 350–400 mm in length.[10] For the male, plasma androgen levels and the diameter of the sexual segment of the kidney have a bimodal cycle with one peak in the spring and the second in late summer. Spermatogenesis occurs in June, reaching its peak in July and August. This is a post-nupital cycle.[11] The rough green snake breeds in spring, and sometimes again in fall. Courtship behavior expressed by males include head-jerking, tail waving, and chin-rubbing. Males align copulatory organs with females in an average of 2 minutes and 45 seconds, and copulation averages 16 minutes and 4 seconds.[12] Females lay 2-14 eggs, occasionally in a communal nest shared by more than one female. Up to 75 eggs have been found in one such nest. The nest site varies: under boards, under bark in rotting stumps, in deep mulch, or under a rock. Hatchlings from spring breeding typically emerge in August or September, and each is about 18– in total length. Male rough green snakes reach sexual maturity in two years. At maturity, males begin storing abundant amounts of sperm in their vas deferens. They are able to mate in the spring of the next year (year 3 of life).[11]
The rough green snake is widespread and is not of conservation concern, in general. However, urban development, especially the reduction of vegetation near waterways, may reduce their numbers. Many are killed on roads, and they may be susceptible to poisoning by pesticides used on their insect prey. When dead, they turn blue. It is also one of the most exploited pet snakes in North America. O. aestivus are collected by the hundreds each year.[13]