(Elaphe obsoleta obsoleta)
Protected Wild Animal
These pictures are of a captive specimen from Wisconsin that was confiscated by the DNR from a dealer who was trying to sell it (which is illegal).
Description: This is one of the largest snakes in Wisconsin, attaining lengths of 40 to 72 inches. Adult coloration is primarily black. Occasionally, faint bands can be noticed within the black dorsal color. The chin, or lower jaw, of this snake is generally white or buff, as are their bellies. Juveniles are often heavily patterned and are easily confused with other snake species. Black ratsnakes are members of the family Colubridae, which includes several non-venomous snakes found within Wisconsin. Within the state, they are most closely related to the western fox snake, with whom they share the same genus (Elaphe).
Habitat/Ecology: Black ratsnakes are reported to prefer bluffside forests, goat prairies, oak woodlots, and old pastures. They are the only truly arboreal (tree-dwelling) snake species found within the state. For this reason, a major food source for these snakes are birds and their young. I was once told by a homeowner in west-central Wisconsin who lived at the base of a bluff about how he was watering his flowers one evening when he saw a large black snake hanging from the shudders of his house in the process of swallowing a bat! This same individual also told me that on one occasion, he left his garage door open all night and when he closed it the next morning, a large black snake slide out. Therefore, it seems likely that these snakes are occasionally found near homes.
Black ratsnakes are constrictors, meaning that they wrap around their prey and slowly squeeze until the prey suffocates, before consuming it. These snakes over-winter in rock outcroppings (occasionally along bluff sides) that go below the frost line. These snakes may hibernate communally with other snakes, and generally emerge in late April when they can be seen basking on bluffy rock outcroppings. Mating is reported to occur in May. Eggs are said to be laid in late June (6 to 22 eggs), with hatchlings emerging after 60 days (approximately).
Remarks: Black ratsnakes are occasionally found in the rafters of barns, where they probably enter to feed upon pigeons or rock doves roosting there. Both this, and their tendency to consume rodents, makes them a beneficial species to have around. It has been reported that black ratsnakes prefer to escape into trees if threatened, but will turn and bite if restrained.
It is interesting to note that these snakes were once also referred to as "Pilot" snakes, because it was believed (falsely) that they guided other species of snakes to over-wintering dens.
UPDATE: Recent molecular DNA analysis has shown that the original classification of the Wisconsin black ratsnake (Elaphe obsoleta obsoleta) is incorrect. It has since been re-classified as Elaphe spiloides, and renamed the "midlands ratsnake". This new designation includes all such ratsnakes existing east of the Mississippi River and west of the Appalachain Mountains.
These snakes are only found in a small corner of southwestern Wisconsin and are rare in the La Crosse area. I have looked extensively but have never encountered one (however, their tendency to inhabit trees makes them more difficult to find). If anyone has seen black ratsnakes near La Crosse, please contact me.
Black Rat Snakes are listed as "Protected" by the Wisconsin DNR and it is illegal to harm or capture them. Violating this law can result in a stiff fine.