Silent Rattlesnakes

   Dear all:  These replies are in response to a query on what seems to be a common perception that rattlesnakes are evolving or de-evolving due to the increase of the feral hog.  The thought among many ranchers and outdoors enthusiasts is that the snakes that rattle soon become hog chow while those that don't go undetected.  I have been told this on several occasions  by landowners, mainly in an effort to warm me of the "greater danger" a silent snake can pose.

  Anyway here are some of the many responses to that query.

Dear Brush,

It's been more than 25 years since I was told this by my graduate advisor,
Harry Greene, then at UC Berkeley and now at Cornell.  Harry is, among
several major interests in reptile ecology, a student of the feeding biology
of pit vipers.  He told me about the differences in behavior of western
rattlesnakes, Crotalus viridis, in the East Bay hills.  Animals living in
Berkeley (I was surprised to learn that numbers of these rattlesnakes lived
in the city!) were retiring creatures that rarely rattled or threatened in
any way, while snakes living on the east side of the hills were more typical
in that they reacted to the proximity of dogs and people, etc., with
assuming a strike posture and rattling.  Snakes taken from these sources
retained their different behavior in the lab, and I think they bred true-
but I am less sure of that breeding experiment, my memory being something
less than once it was.  The distance between these source populations was
something less than twenty miles.

Harry was regularly asked to relocate rattlers found on campus and in the
city.  I believe it was his policy to pick them up in daylight and return
them to their place of capture after dark some time!

My take on this is that rattlesnakes that call attention to themselves
amongst numbers of people cannot be expected to survive long enough to leave
many descendents.

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Brush,
Wouldn't that be an evolutionary modification, taking hundreds or thousands
of generations, with constant pressure needed throughout the process?
Sounds sort of like the folks who figure that Ivory-billed Woodpeckers have
in recent years become fraidy-cats, so that we can't get good looks
at them. Good story-telling stuff, but I dunno.

Greetings Brush:

I have seen twenty-seven rattlesnakes so far this year - as I am close to deaf
in one ear I almost always see them before I hear them and am glad that I am old
enough not to worry about my own gene pool issues - HAH!   All of them rattled
as I moved closer ... and my area is thick with wild pigs.  It would be a tricky
study to do - as we don't really have any, well-documented before data but this
topic has been bandied about by some of my herpetologist buddies.

Brush,

Rattlesnakes. Interesting story - I have been told the same by some, shall I
say "rural", coworkers. During my years of fieldwork on the Callahan Divide,
Stockton Plateau, Concho Valley, south Texas, etc., where rattlers are
plentiful, very few have rattled upon coming across them. Growing up, I was
a snake nut, and we commonly encountered rattlesnakes when looking for
kingsnakes, corn snakes, etc. Very few rattled, unless provoked. I rarely,
if ever, "harass" snakes. The only times that I have seen rattlers "buzz" is
when they are prodded or have rocks thrown at them, etc. I have literally
stepped on them without them rattling. Perhaps it's the weather, I don't
know. I have always wondered if most people upon discovering a rattler,
either out of fear or curiosity, incite the snakes to rattle. Whereas,
myself and others of that strange ilk, just give space and pass on by.
Curious.

Brush,

Dr. Gad Perry brought the rattlesnake subject up in a class a year ago. I don't know how well documented the non-rattling occurrence is, but it seems as though most herpetologists agree that it is indeed going on. I do not believe that hogs have as much to do with it as people do. With the general hatred towards snakes, people are more likely to kill the ones that they see. If a rattlesnake rattles, it is more likely to be seen. That is what I believe the train of thought is. The huge rattlesnake round-ups certainly don't help.

Dear Brush:   Thanks for bringing that up.  We have both hogs and rattlesnakes galore and have noticed that the snakes just do not rattle like they did when we were younger.  Sometimes they do but at night is when they are most active and we often do not hear the ones the dogs find rattle at all..  It is a dangerous time to be out without a flashlight around here.[ ] .We depend on our dogs.  They do a very good job of finding them.   We really hate to kill any of them but if they decide they want to stay around the house or sheds we don't have much choice. []  We think there is some truth to the theory, I have heard a lot of neighbors say the same thing you are asking about.

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Brush:  [].  If the gypsy moths can adapt , why can’t snakes?

Well, between Abilene and Sweetwater there are rattlesnakes that have evolved not to rattle.   Not much to do about hogs.  More about generations-worth of "Roundup" Festivals.  This "a good snake is a dead snake" - mindset is a sad legacy of Homo sapien sapien.  That first book in that Bronze Age desert-religious compilation of books never helped either I suppose.

Utley Birding June 16, 2011

A beautiful warm morning with temperatures only down to 79 at 6:20 . I was eager to get out and about. Still quite a bit of bird song.  Walked a couple of miles of road (?) and enjoyed the exercise and the birds. Also visited with a friend here in Utley and then birded their property spotting an adult Swainson's Hawk. Late or breeding? I have no idea but a good find  for the date regardless.

Another surprise this morning was that of a White-breasted Nuthatch...A pretty rare bird in Bastrop Co. at any time of year but something that was completely off my radar for mid-June. It was north of Wilbarger Creek on Lower Elgin Road near that wooded bottom.

  Coral Snakes seem to be more common than usual despite the drought or because of it.  Not sure what is going on with that but they are easy to hear in the dry leaf litter.  Had a big one this morning cross the road as I was walking.  It escaped being run over by a large truck only by a matter of inches.

  All in all a wonderful morning.

Mid-June 2011 Starr County, Texas

I spent four days in the Upper Rio Grande Valley, birding and vacationing in a county I needed to know better. June is a prime month for this as the motels are dirt cheap and mostly empty. The drought here is horrific but farmers somehow have managed to get in a crop of milo and black oil seed despite there being no rain since last October! The weather is perfect especially in the mornings. The birds are very active as is other wildlife up until around 11:30A. I do not think the temperatures have got much above 102F.  I typically am in the field from the first hint of dawn until noon or 1:00P, then again in the late evening.

There were numerous surprises for me including a pair of nesting American Kestrels. Rare thing here. As well as two nests of Swainson's Hawks.

I really enjoyed the Horned Larks out in the milo fields and elsewhere. Spent a fair amount of time with them. They behave so different than the birds I am most used to directly on the coast and in the large ag. fields slightly inland there. These birds were loud and musical, easier to see, appeared overall darker and most importantly they perched often on the seed heads of milo!  Even singing from them!   Sometimes I could see several at a time doing this. This behavior is something I never see in the same type of fields near the coast. Birds there just hit the dirt and run, they are paler as well.

Just check out how healthy this milo is given it received no rain. It is about ready to be harvested. Indeed the black oil seed was being combined while I was there. It too did very well.
 The next shot is just of a view of the majority of the habitat I was in under a nice soft dawn light


  One of the big surprises for me was finding standing water in an old gravel pit. It was the only water I found except that in water troughs and small ponds being supplied by a well. This gravel pit pond was no more than about 50 feet across but it had one of the best birds of the trip. This female Ringed Kingfisher (above), was away from the Rio Grande River (~30+ miles)....It seemed very out of place. I would have expected a Green Kingfisher in this situ...There she was at this tiny speck of water in the middle of the desert. Likely the only place she could find that had fish, and it had a few small fish as I saw her catch one.

When full of water this quarry makes quite a lake and at it's deepest point it is ~31 feet deep per the rancher. When the kingfisher and I were there it may have had only 2 feet remaining.

Blue Grosbeaks were abundant and could be heard at nearly every stop. I had far too many species to list but Common Ground-Doves were like grasshoppers. They were everywhere and I may have seen upwards of 500+, Likewise Ash-throated and Brown-crested Flycatchers seemed to be everywhere. Hundreds of N. Bobwhites were seen or heard as well a few Scaled Quail but none of them had any chicks and it was reported to me that they just did not breed or are waiting for rain to do so.
Another bird that I was surprised to see so many of were Groove-billed Anis.
 They were scattered everywhere and if they were not seen, the mockingbirds make sure one does  not forget they were present.

There were a couple of species that I am not sure I have ever seen in the county, but perhaps have.  One of those was the Northern Beardless-Tyrannulet ...A tiny thing I heard it sing for a long time before I could spot it in a mesquite across a fence. It was also the first one that I have seen in a couple of years.

In the early cool hours, a few Tarantulas are seen out roaming about. This really big guy was on a mission and did not pause for better photos

The remaining photos are of good old S. Texas ranch land under the stress of drought. Such water spots as pictured are critical in droughts like this one.

Lastly yesterday afternoon a huge fire started burning north of my motel in Rio Grande City. It continued into the night turning the smoke orange and burning away for hours. It was under control by the time I got up early this morning.


Additional photos below

June 5, 2011 ...Thirsty birds

At 102,6 degrees F yesterday afternoon a lot of critters made it in for splish and splash. So many photos but here are a few select ones. Thirteen species of birds were captured at this water location only. Unfortunately the batteries went out I guess on the other water features, but I know by watching those picked up another 3 species including Common Ground-Doves and N. Parulas

If the strange bicolored bill on the young crow remains , it will provide a very useful mark as I watch the crows. If it should survive. Already it is quite tame, learning from it's parents that there is water and other goodies to be had here including cardinal chicks.

The Red-shouldered Hawk made several visits to this pan though there are larger ones elsewhere. This is nothing more than a plugged hot water heater spill pan which is available at any hardware store.

The Roadrunner is just looking goofy for no known reason.

Can't beat the bird baths for entertainment when there ain't no other water to be had.