The story itself is probably exaggerated, but the overall phenomenon appears to be true. Rapid evolution has occurred in the reptile world three different times in the last 50 years or so that I know of. It doesn't fit the purely Darwinian model, but that doesn't mean it isn't true. Yes, natural selection seems to be favoring rattlers that don't call attention to themselves. In Australia, certain snakes have, over just a few generations, tended to have smaller heads, which renders them incapable of swallowing the introduced and toxic Cane Toads there.
KLTV in Tyler did a story on this that they had me weigh in on. DarylOn Oct 31, 2010, at 10:27 AM, Georgia wrote:
Obviously I got this from someone in southwestern Texasâ€¦ but it might be useful info elsewhereâ€¦ since there are rattlesnakes elsewhereâ€¦ Rattlesnakes not rattling?
There's something quaint about a rattlesnake's rattle. The little guy is sending a message. "You chaps are invading my personal space, and I would very much appreciate it if we could part company without hurting each other. Deal?"
Maybe there are others killers in nature that provide a personal warning, but not many.
So all of this is leading up to an interesting phenomenon that some people are observing. A rancher friend forwarded an email with the subject: "Rattlers not Rattling this year---important information." What followed were reports about several encounters with rattlesnakes where the snakes didn't rattle. The theory is that they've learned that the noise they make is as likely to bring them harm as it is to scare away a predator. If it's true, it's not exactly evolution, but it's an interesting environmental adaption. Anyway, here it is reproduced with permission and slight editing:
Subject: Rattlers not Rattling this year---important information
We killed 2 rattle snakes at our dove lease 5 miles South of Midland City limit and the snakes DID NOT rattle. In fact one snake literally went over xxxxxxxxxx,s boots while he was dove hunting. ERAM
I will confirm I have killed a couple of snakes at the lake and Ibex this year and let others go and not one rattled. I poked at one in the Fandangle with a stick before I killed him and despite striking repeatedly at the stick he never made a sound. I thought something was wrong with him before he nearly knocked the stick out of my hand.
We have killed 57 rattlesnakes on two separate ranches this year. Twenty-four (24) at South Bend & thirty-three at Murray , since mid-May. Not one has buzzed! We provoked one fair sized boy with a stick and he coiled & struck at the stick a couple of times before he buzzed up and rattled.
The purpose of this explanation is that I have been hearing the same from fellow ranchers and hunters in regards to the lack of warning with rattlesnakes.
I had lunch with a friend today and he offered a theory about the fact that these dudes aren't rattling anymore. He raised pigs for years and reported that when he would hear a rattlesnake buzzing in the sow pen, the sows would bee line to it and fight over the snake. For the uninformed, pigs love to eat rattlesnakes. Therefore, the theory is they are ceasing to rattle to avoid detection, since there are plenty of pigs roaming the countryside. I have a neighbor ranching lady who was bitten 3 weeks ago, twice by the same snake without any warning ... She spent 5 days in ICU, after 22 vials of anti-venom she is back at the ranch and still may lose her foot or worse yet her lower leg.
The days of perceived warnings are over. Keep your boots on and use a light when out and about. As you all know, one can pop up just about anywhere!
You may wish to forward this to anyone that would be interested.