Opheodrys aestivus, commonly known as the rough green snake, is a species of nonvenomous North American snake in the subfamily Colubrinae of the family Colubridae. The species 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 rarely bites. Even when bites occur, they have no venom and are harmless.
Description
The rough green snake (Opheodrys aestivus) is bright green above and has a yellowish belly, affording it excellent camouflage in green vegetation and making it difficult to see in the wild even though it is relatively common in its habitat. It has keeled dorsal scales, which are arranged in 17 rows at mid-body. It grows up to 116 cm (45+3⁄4 in) in total length (tail included) and is very thin.
Etymology The specific name, aestivus, is Latin for "summer" in reference to the species' green dorsal color. The generic name, Opheodrys, is derived from Greek ophios, meaning "serpent", and drys, "tree".
Geographic range The rough green snake ranges throughout the Southeastern United States, from Florida, north to Southern New Jersey, Indiana, and west to Central Texas. At the edge of the species' population, in states such as New Jersey, Indiana, and Kansas, it is often isolated and dependent on locally humid microclimates. 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.
Habitat and behavior The preferred natural habitat of Opheodrys aestivus is moist meadows and woodlands, typically 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, and upland ravines. The rough green snake also commonly uses disturbed edge habitats alongside roads for thermoregulation and refuge. If kept in captivity it is recommended that it be in a taller enclosure with plenty of cover and climbing opportunities. It is 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.
Diet Opheodrys aestivus is a dietary specialist, preying on insects and other arthropods. The diet of O. aestivus consists mostly of insects and other terrestrial arthropods, but some snails and tree frogs are also eaten. This snake is not a constrictor; most prey are grabbed and overpowered by its jaws which are unusually strong for a snake. O. aestivus has been shown to rely heavily on visual cues for prey detection and to prefer living prey items. As foraging activity increases, the tongue evolves greater elongation and deeper forking, and the abundance of chemoreceptors rises in the vomeronasal organs, the chemosensory responsiveness is adjusted to match diet. Orthopterans constitute 16.9% and all arthropods about 98% of dietary volume of the rough green snake. The rough green snake exhibits greater chemosensory investigation of chemical cues from its insect prey than from representatives of other taxa because of the linked importance of insects to its diet. It is able to live away from standing water by sucking droplets of dew from leaves.
As prey
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). It can also be infested by parasites including species of the genus Cryptosporidium. The rough green snake does not exhibit any predator-resistance capabilities besides fleeing, however it relies heavily on its camouflage. It often undergoes a lot of stress due to human presence.
Reproduction The male rough green snake reaches sexual maturity at an age of two years, and a snout-to-vent length (SVL) of around 24.5 cm (9.6 in). The female reaches sexual maturity around one or two years of age, or when it attains a length of 35–40 cm (14–16 in). 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-nuptial cycle. The rough green snake breeds in spring, and sometimes again in fall. Courtship behaviors expressed by the male include head-jerking, tail-waving, and chin-rubbing. The male aligns its copulatory organs (hemipenes) with the female in an average of 2 minutes and 45 seconds, and copulation averages 16 minutes and 4 seconds. The female lays 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 has a total length (tail included) of about 18–20 cm (7.1–7.9 in). At maturity, the male begins storing abundant amounts of sperm in its vas deferens. It is able to mate in the spring of the next year (third year of life).
Conservation status The rough green snake is widespread and is not of conservation concern. However, urban development, especially the reduction of vegetation near waterways, may reduce its numbers. Many are killed on roads, and it may be susceptible to poisoning by pesticides used on its insect prey. When dead, it turns blue. It is also one of the most exploited pet snakes in North America. Opheodrys aestivus is collected by the hundreds each year.
Subspecies Opheodrys aestivus aestivus (Linnaeus, 1766) – northern rough green snake Opheodrys aestivus carinatus Grobman, 1984 – Florida rough green snake
References
External links and further reading
