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The Herps of La Crosse

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Herps as Pets

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(Pituophis catenifer sayi)

Protected Wild Animal

Pictured above:  The bullsnake is listed as "protected" by the Wisconsin DNR, and it is illegal for private collectors to own this snake within the state.  Note the heavily patterned body and head, which distinguishes this snake from the western fox snake (also see below).

Not a happy fella!  The name "Bullsnake" is said to be derived from this snake's supposedly aggressive behavior, which some call "bullish".  

Description: The Bullsnake is Wisconsin's largest snake, reaching adult lengths of 50 to 80 inches (although rarely getting that large).  Their heads and bodies are heavily patterned with very elongated blotches and bands (see above pictures).  These markings are usually dark brown or black laid over a brown/beige background.  The jaws are buff or cream as is the belly.  The Bullsnake is a member of the family Colubridae, which includes several non-venomous snakes found in Wisconsin.  They are closely related to the Gopher Snakes and true Pine Snakes (which Fox Snakes are often confused with) that exist in other parts of the United States.

Habitat/Ecology:  The Bullsnake is said to be primarily an open woodland/prairie snake; however, I have found them near heavily wooded bluff faces, with open "goat prairies" near the top, along the Mississippi River.  They consume primarily rodents, such as pocket gophers, ground squirrels, and woodchucks, and are beneficial in controlling rodent populations.  Bullsnakes are constrictors meaning they wrap around their prey and squeeze it until it stops breathing before consuming it.  It is said that bullsnakes will actively enter mammals burrows while hunting, during which time they constrict their prey by pressing it against the wall of the burrow.  The nature of their snout (heavily scaled and pointed). and their muscular bodies are probably helpful in burrowing through sand, and pushing their way into mammal dens while hunting.  These snakes may react very aggressively if threatened.  This includes hissing, striking repeatedly, and vibrating their tails.  

Emergence from hibernation has been reported to me as early as mid-April (this depends largely on temperature).  After emergence, these snakes will remain near the den to mate.  Eggs are laid in rotting vegetation, sand-blows, or under debris is late June and emerge in approximately 60 days.  Vogt (1981) reports finding a recently hatched brood of bullsnakes as late as early October.  Bullsnakes are said to over-winter in abandoned mammal burrows (such as gopher mounds), and rock fissures that go below the frost line.  They have been said to hibernate communally with other snake species.

Remarks:  Due to their being found in prairie habitats, which are quickly vanishing from Wisconsin, and the fact that Wisconsin is the northernmost extension of their range within the United States, Bullsnakes are very rare in our state.  The Wisconsin DNR lists them as "Protected" and further research should be performed to determine whether or not this status should be increased to "Endangered".

Vogt (1981) reported that a single Bullsnake can save the average farmer several hundred dollars a season in rodent control.  Therefore, these snakes are incredibly beneficial to humans and should not be harmed for any reason.

The name "bullsnake" is reported to be derived from several sources.  One is this snake's aggressive behavior when cornered, that is said to be "bullish".  Another is their large, powerful bodies, which make them appear "as strong as a bull".  Because of the nature of their mouth, bullsnakes can supposedly produce a louder sound when hissing than other snakes, which may lead to their reputation as overly aggressive.  There is no doubt that an adult bullsnake, coiled and warning a potential threat by hissing loudly, is an imposing sight.  However, while these snakes will defend themselves, if left alone, they are no threat.

    Bullsnakes can be easily confused with Fox Snakes.  The biggest difference, that I can determine, is that Bullsnakes have a heavily patterned head (compared to Fox Snakes) and their jaws are white or cream.  Likewise, their bodies are heavily patterned, whereas the body of Fox Snakes are covered with distinct and isolated blotches.

I have looked extensively for Bullsnakes around the La Crosse area, but have found none.  My only encounter with one was in early May (2002) when I found an individual trying to cross a road off of HWY 35 in nearby Vernon Co.  The habitat was consisted of wooded bluff faces to the east and the Mississippi River across the highway to the west.  Casper (1996) and Christoffel et al. (2000) list them as being found in La Crosse County, so they are probably here as well.  If anyone has encountered Bullsnakes within the area, please contact me.

Because they are a Protected species, it is illegal to harm or capture them in any way.  Violating this law can result in a stiff fine.

Compare these two snakes.  On the left is a Bullsnake, and on the right is a Western Fox Snake.  Note the heavily patterned head of the Bullsnake compared to the fox snake.  Also note how the blotches on the fox snake are mostly isolated, compared to the Bullsnake's, which run frequently run into one another.

Want more bullsnakes?  Who doesn't. 
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