Scientific name: Opheodrys aestivu
Common name:  Rough Green Snake

(Information in this Species Page was compiled by Nihar Ghate in Biology 220W, Spring 2003, at Penn State New Kensington)

The derivation of the rough green snake’s scientific name (Opheodrys aestivus) tells us a great deal about the species. It is a “serpent” (“ophios”) that lives in trees (“drys”) that is active in the warm months of summer (“aestivus”). Other common names for this snake also convey information about the appearance, behavior, and preferred habitats of this snake: “keeled green snake,” “green whip snake,” “vine snake,” and “grass snake.”

Range
The established geographic range of the rough green snake is just to the south of the counties bordering our campus Nature Trail. This broad range extends on a northern line from southern New Jersey west to Kansas (catching the southern-most portions of Pennsylvania), and on a southern line from the Florida Keys into western Texas and Mexico. This species, though, has been observed in local habitats close to our campus Nature Trail.

Behavior
The rough green is universally characterized as a very mild-mannered snake. It will strike and bite on disturbance only very rarely. Most typically the species will present an open-mouthed, “gaping” behavior if provoked trying, apparently, to look larger and more vicious than it is. At rest, this species is usually observed gracefully draped in loose body coils over twigs and branches. Its green coloration is an excellent protective and hunting camouflage in the dense foliage of its tree and shrub habitats. As the snake hangs on its branches, it is seldom (unless it is at a very high state of alertness or caution) motionless. Relatively rapid, rhythmic, lateral head movements are typically observed. These movements are thought to expand the snake’s field of vision and, possibly, even enhance its overall quality and extent of its three-dimensional visual range.

Habitat and Prey
Over their geographic range, green snakes are commonly found in their preferred habitats of trees and shrubs bordering and over-hanging streams and ponds, grassy fields, wet meadows, and shrubs and trees bordering marshes. They are never, though, very abundant or even the most common snake species in their habitats. They readily consume a great variety of soft bodied or hairless insects (including moths, butterflies, crickets, grasshoppers, and many caterpillars) and spiders throughout their active seasons. Prey capture is accomplished by simply grabbing and swallowing as this snake does not have venom nor is it a constrictor. The snake locates its prey visually and also via chemosensory systems involving tongue flicking. Almost all hunting is done during the day. The rough green snake stalks its prey up in its trees or in the grass via slow, graceful movements. It can move rapidly upon disturbance, though, and can even take to the water and swim away to safety.

Mating and Reproduction
The rough green snake has a natural life span of about seven years. Mating occurs most typically in the spring after males have interacted in dominance competitions and after the potential mates have completed a stylized mating ritual. The eggs of the rough green snake are leathery, elongated, and sticky. The female deposits the eggs under flat stones at the boundary edges of her grass and forest habitats, or in rotting logs, stumps, or even up in tree holes. Often more than one female will deposit eggs in a communal ovipositional site. A female can lay from 2 to 14 eggs in a clutch, but 4 to 6 eggs are the most common. The eggs are laid in June or July and will hatch in August or September. The hatchlings are about seven inches long and are a lighter shade of green that the adults.

Hibernation
The rough green snake hibernates during the cold, winter months. Their hibernational behavior is triggered by the onset of cold, winter weather (“consequential dormancy”) which can be advantageous in that the snake is active up to the last minute of their potential season, or, if the winter is very mild, the snake may avoid going into hibernation completely. This type of behavior, though, can also be disastrous and lead to very high rates of mortality if winter sets in too suddenly to allow selection of a proper hibernation den. Typically, a hibernation den will consist of an underground burrow and system of tunnels that the snake digs prior to the onset of winter. The snakes that survive hibernation emerge from their dens in April to begin feeding and then mating.

Predation
The rough green snake has many predators. The black racer and the eastern king snake each readily take green snakes for food. Raptors (hawks and eagles), foxes, and house cats (domestic and feral) also capture and eat green snakes. Human impacts on this species can also be profound. Destruction of habitats favored by the rough green snake is a major cause of the species’ declining numbers. Also, many snakes hunting for insects in grassy areas are killed by lawn mowers, and these snakes, because of their mild dispositions, are also collected to be sold and kept as pets.