Smooth Green Snake (Opheodrys vernalis)

Tetrapoda: Amnitota: Reptilia: Squamata: Serpentes: Colubridae

 Photograph by Suzanne L. Collins & Joseph T. Collins, Lawrence, Kansas. Herpetology collection, University of Michigan Museum of Zoology (slide number 6248)

http://animaldiversity.ummz.umich.edu/site/resources/ummz_herpetology/07.herp.jpg/view.html

Identification:

The smooth green snake is a moderatly long slender snake ranging from eleven to thirty two inches in length.  Its dorsal side is green with its ventral side being a yellowish or white.  The young of this species is a dark grayish olive color ventrally, while hatchlings are more of a brownish, slate gray dorsally. it has a long tapering tail.  This species can be identified from other Idaho snakes because of its color and size.  It is the only green snake found in the state of Idaho(Stebbins 2003).

Distribution: 

This species range is more in the east.  The distribution ranges from southern Canada to western Virginia, over to Wisconsin.  It also can be found in North Dakota, the north eastern corner of Montana an in isolated populations throughout the mid-west.  There is a small population in Texas that is believe to have been introduced and some questionable populations in Mexico and Idaho(Stebbins 2003).

Habitat:

This species is mostly a terrestrial species, though it can sometimes be found in low shrub vegetation.  They are found in wide variety of habitats such as old fields, pastures, farm land(Hulse,Mccoy, Censkey 2001), tops or sides of mountains, boggy areas, low brush areas(Wright and Wright 1957), and clearings in forested areas.  They can be found out in the open, though it is more common to find them under logs or rocks(Hulse et al 2001).

Behavior:

The smooth green snake is a mostly diurnal species that hibernates.  They display a rhythmic lateral head movement that is believed to aid them in locating prey.  They are mostly insectivorous, feeding on caterpillars, crickets, grasshoppers, ground spiders(Hulse et al 2001) slugs, snails, centipedes, millipedes , though they do also feed on salamanders(Wright and Wright 1957).  

Reproduction:

Mating in the smooth green snake occurs in mid- July to late August, however there have been reports of breeding occuring in April.  Due to abiotic factors, such as weather, these dates are not always accurate and may vary from year to year and depending on what part of the state they are located in.  This snake reproduces oviparously, meaning that their eggs develope and hatch outside the body of the mother. Eggs are normally placed under rocks, boards, or vegetation. The clutch size ranges from 3 to 12, varying with the species range and female body size(Wright and Wright 1957). 

Scientific Study:

Grobman, Arnold B. 1992. Metamerism in the Snake Opheodrys vernalis, with a Desctiption of a New Subspecies. Journal of Herpetology 26(2): 175-186.

Note:  The first part of the study went over questionable records of the species.  Idaho is one of the states that is questionable about the existance of this species.  They are believed to be in the in the southeastern corner of Idaho.  There are no specimens collected from Idaho and their prescence is only known by sight records.  This study believes that this species does not occur in the state of Idaho.

Methods:

This study looked at the ventral and caudal scale counts of Opheodrys vernalis as an indicator of metamerism.  The study looked at 2174 specimens, excluding hatchlings and juveniles, and damaged specimens. 

Findings:

The study looked at the effects of many abiotic and biotic factors on metamerism in this species.  Temperature was one of the factors looked at, and it was shown that with each degree increase in temperature there is about a one and three-quarters increase in somites.  Vegetation was a biotic condition that was investigated.  It was shown that the species is restricted to moist areas with grass or shrub growth.  Snakes with high somites are found in areas with moist grasslands, tall and short prairies. The study looked at coloration of this species as well.  The green color of this snake is from a mixture of melanin, a yellow alcohol-soluble pigment, and blue caused by the sculpture of the scales.  They showed that about 2% of specimens lose the blue due to metamersim.  If the specimen has a high or low number of ventral scales, the snake has a higher chance of losing the blue color.  This study also looked at sex of the species and showed that males have a higher number of caudal scales and a lower number of ventral scales.  The males of this species have 7% less ventrals and 13% caudals than females of this species. They also found that the number of somites are constant between the sexes. 

References:

-Grobman, Arnold B. 1992. Metamerism in the Snake Opheodrys vernalis, with a Desctiption of a New Subspecies. Journal of Herpetology 26(2): 175-186.

- Hulse, Arthur C., C.J. McCoy, E.J. Censky. 2001. Amphibians and Reptiles of Pennsylvania. Cornell University Press. Ithaca, New York, USA.

-Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed October 02, 2008 at http://animaldiversity.org. 

Stebbins, Robert C. 2003. A Field Guide to Western Reptiles and Amphibians. Third edition. houghton Mifflin Company. New York, New York, USA.

-Wright, ALbert Hazen, Wright, Anna Allen. 1957. Handbook of Snakes. Comstock Publishing Associates.  Ithaca, New York, USA

Created by Christina Damm