Home & Garden Columns

The Sometimes-Mellower Gopher Snake: A Great Pretender?

By Joe Eaton, Special to the Planet
Tuesday May 23, 2006

Although I’m a Southerner by birth and upbringing, I’ve never handled a snake in a religious context. Our church didn’t even use tambourines. All I know of the spiritual side of snake-handling comes from books like Dennis Covington’s memoir Salvation on Sand Mountain and Weston LaBarre’s more scholarly They Shall Take up Serpents. 

Secular snake-handling is another story. Depending on the disposition of the snake, it can be a pleasurably relaxing experience (for the handler if not the reptile). A few weeks ago, I was at UC’s Museum of Vertebrate Zoology for the Cal Day open house, passing around a large but tractable Colombian red-tailed boa constrictor and talking about snakes, when I got some gratifying news from a young naturalist named Henry. Henry and his father said they had been finding gopher snakes at the Berkeley Marina. I was thrilled, in fact: I had no idea they were still around. 

If you want a snake for handling, I would not hesitate to recommend a gopher snake—especially a gopher snake that hasn’t completely warmed up yet. A warm gopher snake can be feisty.  

On the other hand, I wouldn’t advise picking up a garter snake, a decorative but foul-tempered creature with disgusting habits. 

When a gopher snake is averse to being handled, it will let you know. It coils up, flattens its head, hisses, and vibrates its tail rapidly. Against a substrate like dry leaves, the effect of the tail vibration can be very rattlesnake-like—a resemblance that was first noted by the Lewis and Clark expedition, and that has probably gotten a number of gopher snakes killed.  

Some biologists have claimed that this performance is a case of Batesian mimicry, in which a relatively benign creature has evolved a resemblance to another species which is venomous, otherwise dangerous, or at least unpalatable. They also claim that gopher snakes and western rattlesnakes have similar color patterns. 

Henry Walter Bates, one of those 19th-century British amateurs and author of The Naturalist on the River Amazons, described the phenomenon in tropical butterflies. The classic instance of Batesian mimicry among snakes is, of course, the nonvenomous milksnakes and kingsnakes whose red-black-and-yellow banding resembles that of the venomous coral snakes. The viceroy butterfly is a Batesian mimic of the distasteful (to most birds, although not to black-headed grosbeaks) monarch. Behavioral mimicry is rarer, but there are examples. 

But is that really what’s going on with the gopher snake and the rattlesnake? In the 1980s, Samuel Sweet at UC Santa Barbara decided to test the notion by comparing several California populations of the two species. He hypothesized that the snakes’ microhabitats might have something to do with the degree of resemblance. Rattlers and gopher snakes overlap broadly in habitat preference, but previous studies had shown rattlesnakes to be more common in chaparral and woodland, and gopher snakes to be more common in open grassland. Where trees and shrubs are scarce, as in the Carrizo Plain, both are found in grassland. 

Sweet photographed snakes of both species against backgrounds of coastal grassland, Carrizo Plain grassland, and mountain chaparral, and analyzed the extent to which the snake’s pattern matched its setting. He found that gopher snakes were more visually cryptic in grassland, rattlers in chaparral. For both coastal and mountain populations, rattlesnakes and gopher snakes had significantly different patterns. 

It was only in the Carrizo Plain that rattlers and gopher snakes really looked alike. And it was in this habitat that both species were equally cryptic. The implication Sweet drew from this was that there was no model-mimic relationship: gopher snakes had not evolved to look like rattlesnakes. Instead, each species had evolved to blend into its preferred microhabitat, to conceal itself from predators and prey. Where the microhabitat was the same, the patterns were similar—but this was the result of convergence, not mimicry. 

What about the head-spreading and tail-vibrating, though? Sweet pointed out that other nonvenomous snakes that don’t particularly resemble rattlers—among them, racers, corn snakes, kingsnakes, whipsnakes, and indigo snakes—have comparable, if somewhat less intense, defensive displays. This suite of behaviors seems widespread in venomous and nonvenomous snakes alike. Although it would have benefited any nonvenomous snake to be mistaken for a venomous one, he concluded that there was little direct evidence that the gopher snake was a behavioral mimic of the rattlesnake.  

It’s interesting that California ground squirrels, who’ve had a long evolutionary relationship with both rattlers and gopher snakes, have no trouble telling them apart. But the squirrels are fooled by the uncannily rattler-like vocalization of the burrowing owl, which holds up better than the gopher snake’s display as an example of behavioral mimicry.  



Photograph by Bob Dyer / Petaluma Wetlands Alliance 

A young gopher snake winds his way through the sand at Petaluma’s Schollenberger Park.