Last updated 22 May 2007: updated Introduction and species details.

A Look at the Family Colubridae


Green Rat Snake


A monotypic genus consisting of another former Elaphe species. In this case the genus was set up on the basis of characteristics of the hemipenes.

Scientific Name Common Name Distribution Size Notes
Senticolis triaspis Green Rat Snake USA, Mexico, Central America from Guatemala through to E. Costa Rica 4-5' R D Bartlett notes that in many years in the species' range he has only spotted one a very few times. This is another rat snake that is actually hard to maintain in captivity: a period of brumation seems to be absolutely necessary (Bartlett & Bartlett), and despite the creature's Latin American range the Bartletts recommend a temperature range in the low to mid seventies Fahrenheit. They note that the specimens from the north of the snake's range are particularly sensitive and do not tolerate much humidity despite their apparent preference for forest stream habitat. Those Senticolis taken from the wild will probably also be carrying a heavy load of endoparasites. There are three subspecies, but their validity has been questioned not least because of the small number of specimens involved. Despite their common name, these rat snakes are often not green but brown: as a rule the green ones are found in the more northerly part of its range, whereas the brown ones come from further south or more humid parts. In the wild they eat mammals (including bats), birds and lizards, but keepers have noticed that they can be extremely fussy: wild mice (such as deer mice) seem preferred to the ordinary prekilled species, and hatchlings prefer lizards. Until more work on both the natural history and captive husbandry of Senticolis has been carried out, this species should be left to specialists and experts. Scalation details: 8 supralabials, of which 2 enter orbit; dorsal scales weakly keeled, paired apical pits present on some scales but often indistinct; 29-39 rows at midbody; lateral scalation smooth; ventral scalation angulate; anal plate normally divided. Other: head moderately narrow, distinct from neck; eyes relatively small, pupil round. Coloration: see subspecies. Reproduction: in the Yucatán, may take place throughout the year; clutch size 3-7 eggs.  B I
S. t. triaspis Mexico (Yucatan), E Guatemala The nominate subspecies is actually normally tan, grey or reddish-brown (not green!) overall. Unlike the other two subspecies, this one retains a body patterning into adulthood, 43 (normally ³45)-73 dorsal saddles and some lateral blotches. The saddles may be outlined in black (Staszko and Walls). The Bartletts note that it may be found in both thorn scrub forest and agricultural land.  B I
S. t. mutabilis Guatemala to Costa Rica Subspecies tends to lose juvenile pattern with age and become tan to reddish-brown in colour, with any patterning on the back only vague and sometimes completely absent.  B I
S. t. intermedia USA (SE Arizona, SW New Mexico) through to Mexico (Chiapas) These are the truly "green" snakes of the common name, the overall colour usually being some shade of green (olive, lime or grey). Juvenile dorsal saddles and blotches disappear with age or may appear faintly on the back.   B I


Rat Snakes: A Hobbyist's Guide to Elaphe & Kin, Ray Staszko & Jerry G Walls, TFH 1994.

Corn Snakes and Other Rat Snakes (Complete Pet Owner's Manual) by R D & P Bartlett, Barrons Pet Series 1996.

Field Guide to Amphibians and Reptiles of the Maya World, Julian C Lee, Cornell University Press, 2000.


Index of ratsnake articles (on this site).

The Bushmaster Breeding Centre in Germany specialise in breeding rat snakes, and their homepage has some outstanding photographs of various Elaphe and other species. There is also a link to the US site.

Mick Spencer has provided a very attractive table of the Elaphe, Bogertis and Sentalis species with their subspecies, common names and distribution.

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