Eastern Indigo Snake Recovery Plan

Speake, Daniel; McGlincy, Joe; Diemer, Joan

The eastern indigo snake, Drymarchon corias couperi (Holbrook) is on of eight subspecies of a primarily tropical species. Spanning some 55 degrees of latitude, the overall range of Drymarchon corais extends from the south-eastern U.S. Coastal plain to northern Argentina (Smith 1941). Six of the eight subspecies are distributed in south or central America; only the eastern indigo and the Texas indigo (Drymarchon corais erebennus) occur within the United States. The eastern indigo is very large, fairly stout snake attaining a maximum total length of about 8 1/2 feet. The head is slightly, if at all, distinct from the neck; anal plate undivided, scales large, smooth, shiny, in 17 rows at midbody. The color is uniform lustrous blue-black, except for some reddish or cream-colored suffusion about the chin, throut, and cheeks. Spectacular coloration is not the eastern indigo snake's only phsical attribute; the size of the animal is noteworthy as well. Adults average 1.8 m (6 feet) and the maximum recorded size is over 2.6 m (8.6 feet) (Conant 1975). This places the subspecies in contention for the title of the largest colubrid snake in North America. Despite its size, the eastern indigo snake is often mistaken for other black snakes within its range. Smaller specimens may resemble the common black racer (Coluber constrictor); however, the latter is generally a slender, fast-moving snake with a white chin and less glossy coloration, Positive identification can be achieved by inspection of the anal plate: single in indigos and divided in racers.