Sorry, but I’m going to call a big BS on that. After more than 12 million years, they’re not suddenly thinking “Damn, I want to bite people, but only that noisy rattle keeps giving me away,” and “learning” from gopher snakes not to rattle.
Rattling is an evolved trait, intended to give warning: “Stay away!”
If only we would learn.
Actually, our gopher snakes will raise and “rattle” (i.e. rapidly vibrate) their tails, and assume rattler-like striking postures when threatened without an escape path. Not sure how that works for them, but the practice must come from somewhere.
I don’t know what neighborhoods might have bred silent rattlers by generations of freaked out “outdoorsmen” chasing the noisy ones around with shovels and pistols. Around here, they pretty much go away when given a little patience, a little space, and a little calm encouragement. Then they can go back to keeping the mice and gophers at bay.
Yep, I had a “pet” gopher snake when I was a kid. He used to do that when the dog came near. I don’t know if it’s an example of evolutionary mimicry like the viceroy and monarch butterflies, or just a physiological reaction to threat.