SREL Reprint #0543

 

 

 

Selected Aspects of the Life History of the Rainbow Snake (Farancia Erytrogramma)

J. Whitfield Gibbons, John W. Coker and Thomas M. Murphy, Jr.

 

Abstract

Rainbow snakes, Farancia erytrogramma, were collected around a Carolina bay in South Carolina over a 2-year period through continual use of a terrestrial drift fence and pitfall traps.  Data collected on more than 100 specimens from the field populations were complemented with examination of >200 museum specimens.

Relative tail length was a reliable indicator of sex in specimens of all sizes.  All known-sex females (N=27) had tail proportions <15% of the total length, whereas 53 males had tail proportions >16%.  Sexual dichromatism was confirmed for the species.  The males had significantly more ventral and less subcaudal spotting females.  The most parsimonious explanation is that comparable amounts of melanin are allocated to a body region independently of sex but, because of the dimorphism in tail length, females have more melanin concentration in the subcaudal region, whereas, males have a higher concentration on the ventral surface.

Hatchling F. erytrogramma begin their first growing season at total lengths of 20-30 cm.  A year later they are 45-55 cm long.  Males presumably reach sexual maturity by the end of their second, or beginning of their third, growing season at lengths approaching 70 cm.  Females are mature at an age of no more than 3 years and a length of 90 cm.  Females attain lengths of 1.3-1.6 m whereas males are seldom more than 1.0m.

The capture of hatchlings and 2-year-olds entering the aquatic area in 2 consecutive years provided information on seasonal activity of immature individuals.  Hatchling F. erytrogramma presumably overwinter on land in the vicinity of the nest.  In March and April they move overland to an aquatic area where they remain if conditions are suitable.  If the aquatic habitat becomes undesirable, individuals may move to neighboring aquatic sites.  This strategy would have selective value in the southeastern coastal plain where many aquatic habitats have unpredictable, fluctuating water levels from year to year.

Initial activity in March and April was generally associated with higher temperatures but precise relationships cannot be defined at this time.  Precipitation did not appear to influence activity during this period.

 

SREL Reprint #0543

Gibbons, J.W., J.W. Coker, and T.M. Murphy Jr. 1977. Selected aspects of the life history of the rainbow snake (Farancia erytrogramma). Herpetologica 33:276-281.

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