Tiger Rat Snake, Spilotes pullatus - Reptilenesia

Other common names: Tigre, El Tigre.

Size. Adult males larger than females. Average size is about 1,700 mm SVL, 2,311 mm TL, may exceed 3.6 m; hatchlings average 376 mm SVL; tail about 32% of SVL.

A Tobago specimen. JCM

Identification. A large black and yellow snake with 16 or 18 rows of keeled dorsal scales that are reduced to 10 rows posteriorly. Yellow or white colouration is restricted to the anterior portion of the body. Tobago specimens tend to be darker than Trinidad and mainland specimens. Rostral visible from above; nasals semi-divided or divided; loreal single; one or two preocular; one or two postoculars;  six to eight upper labials, six to eight lower labials; ventrals 209−226; single cloacal plate; divided subcaudals 116−129; dorsal scales smooth in first two rows, other rows keeled. 

Similar species. Perhaps most easily confused with Spilotes sulphureus which has 21 dorsal scale rows and much more yellow in the dorsal pattern. Clelia is a solid blue-black as an adult with 19 scale rows at mid-body and a much shorter tail (62−76 subcaudals).

Distribution. Widespread, ranging from Mexico southward to Argentina; present on both Trinidad and Tobago. Many more specimens of this snake have been found on Tobago than on Trinidad. Tobago specimens occur from the highest forests down to littoral forests adjacent to the beaches. A specimen recently found at Cedros, Trinidad suggests the species is found island wide.
Habitat. Forested and forest-edge environments. It is arboreal but will come to the ground and use open habitats.

Biology. Diurnal. The diet includes birds and their eggs, but small mammals including bats, rodents, and the invasive mongoose are killed by constriction. The diet suggests the Tiger Rat Snake is an active forager and often a nest predator.

Male Spilotes pullatus engage in ritualized combat, a behaviour that has been reported in many other snake species. This behaviour may be used to maintain a territory or settle a dispute over access to a female. The male snakes partially entwine their bodies during combat and attempt to keep the head upright and above the other male. During the combat ritual, the snakes use their tails to restrain their opponent by preventing the opponent from moving forward. Biting during combat has not been observed in this species.  The bouts may last for more than an hour. Reproduction: Seasonal reproduction is likely at higher and lower latitudes, with year-round reproduction likely at middle latitudes. Egg-laying has been reported in early summer, hatchlings found in early July. Clutch sizes of 5-11 eggs reported.

Defensive behaviour includes inflating the forebody with the trachea, loud hissing, and tail vibration. The bottom photo in plate 145 shows the defensive behaviour  that expands the forebody and exposes the skin between the scales. This behaviour is shared with the Yellow-bellied Puffing Snake. The unusual behaviour of kinking or bending the