Rattler Tattler at North Table Mountain

Bryon Shipley

ABOUT THE CONFUSION WITH
BULLSNAKES AND RATTLESNAKES
(apply to gopher snakes, too)
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Typically, stories about bullsnakes and rattlesnakes include one of the following:

 
1.Bullsnakes eat rattlesnake eggs.
2.Bullsnakes eat rattlesnakes.
3.Bullsnakes and rattlesnakes breed together.
4.Bullsnakes chase away rattlesnakes.
Bullsnakes are venomous
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Unfortunately, these imaginative stories turn out to be myths, and the biggest problem concerning the confusion of bullsnakes and rattlesnakes is in the mistakes of identifying these snakes.  Misidentification leads to all sorts of misinterpretations, complicated by the vibrating tail tip, which represents a defensive response to a predator.  This behavior is found in many non-venomous snakes, many of whom do not share their home with rattlesnakes.
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​Let’s find some truth in these myths:

1. Bullsnakes eat rattlesnake eggs:  Since rattlesnakes do not lay eggs, this cannot be true.  It is hard to imagine where this idea came from, although most likely it was a case of mistaken identity.  Perhaps bullsnakes were observed eating some kind of egg, which does happen, but the confusion was that for some reason, the rattlesnake was seen near a spot where these eggs were laid (by some other creature) and were unearthed, or were brought to the surface by the digging activities of the bullsnake, while she was excavating a burrow for her own eggs.  Alternative explanations are endless.      
2. Bullsnakes eat rattlesnakes:  A thorough search of the literature and discussions with researchers who study both snakes has revealed very little support for this idea.  In one instance, the body of a small rattlesnake showed up in the gut of a bullsnake, but no information exists on whether the ingested rattlesnake was already deceased or even what species it was.  Another study of greater than 1000 specimens (museum and live) showed that only 0.4% of the diet consisted of snakes of some kind, only 2 of these were actually rattlesnakes.  Again, whether these consumed rattlesnakes were scavenged or outright killed and eaten is up for speculation.  Regardless, the rarity of rattlesnakes being consumed would have no controlling effect on rattlesnake populations.  Bullsnakes primarily eat warm-blooded prey (small mammals, birds and their eggs) through virtually all of their age classes.  However, the natural mortal enemy of rattlesnakes is, in fact, the kingsnake.  Is it possible that someone would more likely have seen a kingsnake, coachwhip, or juvenile racer kill and consume a rattlesnake, as opposed to a bullsnake?  Again, there is the problem of positive snake identification.                                                                                                                                                    
3. Bullsnakes and rattlesnakes breed together:  In fact, rattlesnakes are live-bearers and bullsnakes are egg layers, thus, successful breeding could never occur due to the biology involved. A couple of things come to mind for an explanation.  One, rattlesnakes and bullsnakes commonly hibernate together, along with other snakes and sometimes amphibians.  If they were observed emerging from a den in the spring together and young rattlesnakes were included (which have few rattle segments, or one) one might conclude that they obviously must have hybridized and produced young.  Two, because newly born rattlesnakes (from the previous fall) don’t have a rattle string, these snakes may be confused as being bullsnake / rattlesnake hybrids or simply bullsnakes.  Occasionally, an adult rattlesnake will not have a rattle string due to previous injury.  Bullsnakes (and other non-venomous snakes) commonly vibrate their tail tip when threatened, a behavior commonly interpreted as rattlesnake mimicry. Tail vibration is sometimes believed to be the result of bullsnakes and rattlesnakes breeding together, further confusing facts.  Note: Non-venomous snakes which do not coexist with rattlesnakes in their habitat also vibrate their tail tip.                                                                                            
4. Bullsnakes chase away rattlesnakes:  Bullsnakes and rattlesnakes can have alternating activity periods that give the appearance of one snake causing the elimination of the other. After emerging from hibernation with bullsnakes and other snakes in the spring, rattlesnakes soon switch to a mostly nocturnal schedule to avoid heat, and therefore, are not nearly as noticeable in the daytime as they were in early spring, while bullsnakes are still being observed during the day.  It has also been suggested that bullsnakes eat all of the rattlesnakes’ prey, thereby driving the rattlesnake away for lack of food.  

​Comments on identification:

            Unless one is very familiar with identification of different snake species, using color patterns can be very confusing; but from a distance, one can focus on two things:  the shape of the head and the shape of the tail.  Bullsnakes, like so many harmless snakes, have a head which can be described as bullet shaped. The head width is very close to the width of the neck.  The tail is long and tapers gradually into a sharp point (like so many other harmless snakes).  In contrast, the rattlesnake has a triangular-shaped head, wider than the neck. Their tails are blunt and short compared to the body, almost always ending with a rattle, although newborns have only a single segment for their rattle.  Rattlesnakes are stockier and heavier in body shape (as adults) compared to the slender, but robust bullsnake. In most cases, if one observes a motionless snake in a tight, concentric coil, it will most likely be a rattlesnake.
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Bullsnakes (=gopher snakes) and rattlesnakes have always coexisted in the same habitat. Thus, it seems contrary that if bullsnakes and rattlesnakes are so incompatible with each other and bullsnakes are so good at repelling rattlesnakes, as many generations of people would have us believe, then why are they still found together?

Bullsnake

Prairie Rattlesnake