HerpIndiana

Black Ratsnake (Pantherophis obsoletus)

Description

A large, mostly black snake with some lighter patterns. Adult Ratsnakes are long, muscular snakes with dark dorsal coloration. Juvenile Ratsnakes are grey with black blotches, and this pattern fades with age. Ventral coloratin has blotched pattern. Ratsnakes have slightly keeled scales down the center of the back, but the scales are smoother along the sides. Adult Ratsnakes reach typical lengths of 4 or 5 feet, though individuals reaching 6 feet is not entirely uncommon. They have 8 upper labials and 10-12 lower labials, with 21-27 scale rows at midbody. The anal plate is divided (Minton 2001, 299-301).

Distribution

Ratsnakes range throughout most of the state, with the exception of several counties in the northwest prairie regions. The range of the Black Ratsnake (Elaphe obsoletus obsoletus) covers most of the state, with the Gray Ratsnake (Elaphe obsoletus spiloides) present in the southwestern corner. Intergrades are found throughout the southern part of the state (Minton 2001, 301).

Activity

Minton reports that his earliest records for the Ratsnake are in early March, though they are not often seen until May. He says that the prime times to find these snakes are in late spring to early summer, which I find to be consistent with my records. He has found them through late October, though they can be found throughout the year at their overwintering sites (Minton 2001, 303).

Taxonomy

Ratsnakes are part of the genus Elaphe, which contains another species in Indiana, the Western Foxsnake (Elaphe vulpina). Two subspecies of the Black Ratsnake can be found in Indiana. The Black Ratsnake (Elaphe obsoletus obsoletus) is the most widespread, but the Gray Ratsnake (Elaphe obsoletus spiloides) is present in southwestern Indiana.

Natural History

Black Ratsnakes seem to be fairly tolerant to many habitats, though they prefer wooded areas. They are often found in and around farms, where most farmers respect them due to their aid in controlling rodent populations. Ratsnakes breed in late spring or early summer, and their eggs hatch in late summer and early fall. Ratsnakes feed primarily on mammals and birds, using constriction to kill most prey. They are known to prey upon birds and eggs in the birds’ nests. Young Ratsnakes may eat amphibians and lizards as well (Minton 2001, 302-305).