Here are some of the
most common myths associated with Mohave Rattlesnakes (also called “Mohave
greens”) in southern California:
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Myth – “Mohave
greens” are hybrids of a deadly green exotic species (mambas are often
mentioned) with local harmless snakes that first appeared near Barstow in the
early 1970s.
Fact - Mohave rattlesnakes, known as Crotalus scutulatus to biologists, are
just one of about twenty species of rattlesnakes. They were first described by
Smithsonian Institution biologist Robert Kennicott in the Proceedings of the
Academy of Natural Sciences of Philadelphia in
1861. Recent DNA studies have estimated that Mohave rattlesnakes
separated genetically from their closest living relatives, prairie rattlesnakes
(Crotalus viridis), and became a
distinct species somewhere between 26 million and 4 million years ago!
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Myth – “Mohave
greens” are very deadly hybrids for which there is no antivenom and that were
intentionally produced by the U.S. government to be put down Viet Cong tunnels
during the Viet Nam War. After the war, the surplus snakes were released in the
desert near Barstow. (This, the wildest and most specific version of this
common myth, came from a guy who called in to a radio show (Victorville station
KCIN, on the morning of 26 April 1991) while I was being interviewed about
snakebite)
Fact - This is so ridiculous as to hardly merit a
response. See the information provided regarding the first hybrid myth (above).
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Myth – “Mohave
greens” have no rattles.
Fact - Mohave rattlesnakes, like all rattlesnakes,
routinely grow a rattle. It’s a brittle structure that is divided into hollow
segments that fit loosely together and make noise when the snake shakes its
tail. A new segment is added at the base (the oldest segment is at the tip)
each time the snake molts or sheds the outer layer of its skin. This normally
occurs several times each year, depending on how fast the snake is growing.
Mohave rattlesnakes undergo this process as surely as other rattlesnake
species.
Rarely, like all other
animals, rattlesnakes are deformed by either congenital birth defect or by
traumatic injury. A handful of rattlesnakes of several species have been
documented over the past several decades that had either badly deformed rattles
or a blunt stump of a tail without a rattle. One of these was the carcass of a
male Mohave rattlesnake with a rattleless stump. This carcass has been
examined, x-rayed, and analyzed to determine the cause of the deformity.
Several experts who have examined the photos and x-rays agree that the
deformity is most likely the result of an old injury that healed long before
the snake’s death, however, due to the carcass having been repeatedly frozen
and thawed prior to examination, a conclusive finding by microscopic analysis
of the cell structure of the stump is not possible.
It is interesting to note that the “rattleless
rattlesnake” that is an occasional subject of nature films is an actual
species, Crotalus catalinensis, that
is found on a single island near the tip of Baja California – Isla Santa
Catalina. However, it is not truly “rattleless.” Indeed, it produces a new
rattle segment each time it sheds its skin, just like other rattlesnakes. The
difference is that this species has lost the characteristic shape of the
segment so that the segments no longer
lock together effectively, thus the older segment is lost each time a new
segment is produced. So, while this animal does not accumulate a series of
interlocking segments capable of making noise, it does have a single rattle
segment at the end of its blunt tail. Anyone familiar with rattlesnakes would
not mistake this animal for anything else.
And it is only distantly related to the Mohave rattlesnakes of the arid
mainland.
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Myth – “Mohave
greens” give birth to 150 babies at a time and produce several litters a year;
they are rapidly eating the native snakes.
Fact - First of all, Mohave rattlesnakes are
native snakes. And it is well established from dissections of pregnant females
killed on roadways and other preserved museum specimens, in addition to many
captive births, that the average litter size for Mohave rattlesnakes is eight
with the largest recorded litter being thirteen. These numbers are very
consistent with other rattlesnake species of about the same size (larger
species tend to produce larger litters but even the largest litters recorded
for big eastern and western diamondbacks are in the low 20s). Rattlesnakes, at least
in temperate climates like North America, do not produce more than one litter
per year - and there is usually at least a year or more between litters.
Mothers routinely drop 30% to 50% of their body weight during birth and must
replenish their stored body fat before they can sustain another pregnancy.
Mohave rattlesnakes are primarily rodent eaters.
While other snakes may rarely be eaten, analysis of their stomach contents has
not disclosed evidence of this and they are not considered snake-eaters by
biologists. They are routinely and successfully kept captive in cages with
other snakes.
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Myth – Bites by
“Mohave greens” are always fatal and antivenom doesn’t work against their
bites.
Fact - It is
commonly estimated that around 8,000 venomous snakebites occur in the United
States each year, resulting in roughly 5 to 12 deaths nationwide. Most of these
deaths occur in states like Texas, Arkansas, Louisiana, Mississippi and Georgia
– places were lots of people are bitten by big rattlesnakes (with the exception
of the Big Bend area of western Texas, Mohave rattlesnakes are absent from
these places). Despite many annual rattlesnake bites in California and Arizona,
many of which are inflicted by Mohave rattlesnakes, years go by between deaths
in these states and other species are often responsible for the few people that
do die.
Rattlesnake antivenom has recently undergone the
first change in half a century in the United States. The older product,
Antivenin (Crotalidae) Polyvalent by Wyeth Laboratories, was routinely used
successfully to treat Mohave rattlesnake bites (although Mohave rattlesnake
venom was not actually used to make it). However, since October 2000, CroFabTM has been
replacing the older product. CroFabTM is a vast
improvement, primarily due to the cutting-edge process used to make it. Like
the Wyeth antivenom, the venoms of four species of snakes are used to make
CroFabTM but they are different species – and one is the Mohave
rattlesnake. Consequently, even though CroFabTM is intended for use against the venom
of a wide variety of North American pit vipers (as Wyeth antivenom was), it is
also a specific antivenom for Mohave rattlesnake bites and
works quite well.
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Myth – Mohave rattlesnake
venom remains dormant in the body for years and turns your blood to jelly later
in life.
Fact - The
“short answer” is that rattlesnake venoms do their damage within hours or days
and, if they effect blood clotting at all, it’s usually to interfere with
clotting, causing bleeding from the gums, gastrointestinal, and urinary tracts,
in severe cases.
All snake
venoms, including the venom of Mohave rattlesnakes, are complex cocktails of
dozens of enzymes and other proteins that vary between species, between
geographic populations of the same species and even with age in single animals.
These biologically active compounds begin causing damage immediately upon being
injected and they continue to cause damage continuously until they are either
consumed by the process or neutralized by antivenom administered by a physician
or the body’s own immune system. The damage often peaks within the first day or
so and, especially if not properly treated, may continue over several days.
Mohave
rattlesnakes are widely considered to produce one of the most toxic venoms of
any North American rattlesnake due to a potent nerve poison in their venom. This
was determined from studies comparing venoms drop-for-drop in laboratory
mice – it has nothing to do with killing a lot of people; other
species (like eastern and western diamondbacks) actually kill many more humans.
Interestingly, bites by most Mohave rattlesnakes usually cause very little
damage to the circulatory system and soft tissues around the bite, while the
bites of most other rattlesnakes produce serious soft tissue damage and often
damage the blood’s ability to clot. Neurological effects are minimal in many –
but not all – other species.
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Myth – Mohave
greens are expanding their range and can now be found in coastal southern
California, far from the Mohave Desert.
Fact - At least
in California, Nevada and Utah, the distribution of Mohave rattlesnakes is
restricted to the Mohave Desert (they are found in the Sonoran and Chihuahuan
Deserts in Arizona, New Mexico, Texas and Mexico). In California. they are
restricted to the desert areas of San Bernardino and Los Angeles Counties and
the southeastern corner of Kern County. With the likely exception of some areas
in Joshua Tree National Park, Mohave rattlesnakes are not found south of San Bernardino
County in California; they are absent from desert areas in Riverside, Imperial
and San Diego Counties. Some old museum specimens originally identified as
Mohave rattlesnakes from Riverside and Imperial Counties have been re-examined
and found to have been misidentified western diamondbacks (C. atrox). Similarly, some old specimens logged as western
diamondbacks from northwestern San Bernardino County and southeastern Kern
County have recently been determined to be Mohave rattlesnakes.
There is no credible evidence of Mohave rattlesnakes ever having
naturally occurred in the mountains or coastal foothills and valleys of
southern California, despite anecdotal accounts and reports in the popular
press (e.g., San Diego Union-Tribune,
25 March 2000, page B-1: “Rumors have it that the bad boy of rattlesnakes may
have come to town”). Many snakes, particularly the common southern Pacific
rattlesnake (C. helleri) of the
mountains and coastal foothills, can have a distinct greenish iridescence and
are undoubtedly mistaken for “Mohave greens.”
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Myth – Mohave
greens are highly aggressive toward people, much more so than other
rattlesnakes.
Fact - Although
people frequently tell exciting tales about being attacked and even chased by
rattlesnakes, and Mohave rattlesnakes are often cited as being “highly
aggressive” or the “most aggressive,” biologists and others who come into
frequent contact with these animals are never “attacked.” That’s not to say
that rattlesnakes – Mohaves included – won’t defend themselves enthusiastically
when bothered. The simple fact is that most rattlesnake bites occur when people
intentionally bother the snakes and just get too close. The way to avoid being
bitten is to stay out of reach – a distance about equal to the length of the
snake. This includes being careful where you put your hands and feet in
rattlesnake country and, above all, leaving the snakes alone when you find
them.
In my
lifetime of dealing with rattlesnakes, including my recent four-year
radiotelemetry study of Mohave rattlesnakes (that yielded more than 3,800
recorded close encounters with 85 wild “Mohave greens”), I have never had one
do anything except attempt to defend itself if I bothered it. And of the many
dozens of herpetologists and other researchers I know with similar years of
rattlesnake experience, each one will tell you the same thing:
Leave them alone and they’ll leave you alone!
FOR MORE INFORMATION YOU CAN TRUST:
The Venomous Reptiles
of the Western Hemisphere (2004, Cornell University Press)
I consider
this two-volume book by Jonathan Campbell and William Lamar to be the best
single reference available today regarding both the snakes themselves and
snakebite. Campbell and Lamar are eminently qualified biologists who have
exhaustively researched and referenced their book; you will find all the biological
detail you want, as well as where they found their information (although each
has a lifetime of personal experience with the snakes, too). Several other
contributors round out the book, including Dr. Robert Norris, who authored the
excellent chapter on snakebite in North America. Dr. Norris is a world-renowned
snakebite expert and currently Chief of Emergency Medicine at Stanford
University Medical Center. His chapter is exhaustively referenced, as well.
You’ll probably have to go to a university library to find this
book, unless you are willing to shell out more than $100 to but it.
Snake Venom Poisoning (1983, Scholium International)
This is a
classic snakebite reference written by Dr. Findlay Russell, a physician who pioneered
modern snakebite treatment in North America. Dr. Russell goes into the epidemiology
of snakebite, including which states account for the most snakebites and
snakebite-related deaths. His book is still of immense value.
This book is still available for around $50.
Rattlesnakes, Their Habits, Life Histories, and Influence on
Mankind (1997 [2nd edition], University
of California Press)
This is the
“rattlesnake bible” that is on the shelf of every biologist with an interest in
rattlesnakes. The author, Laurence Klauber, spent a lifetime investigating
rattlesnakes, and his two-volume book is a compilation of his efforts,
including correspondence from many collaborators around the country. He covers
every conceivable aspect of rattlesnake lore, including classification, physical
characteristics and abilities, reproduction, food, enemies, venom, etc., as
well as chapters like “Myths, folklore, and tall stories.”
One word of
caution: although Klauber’s chapter on “Treatment and prevention of the bite” is
a fascinating history lesson concerning the sometimes misguided efforts to help
rattlesnake bite victims prior to 1956, it
must not be used as a guideline for first aid or treatment of snakebites
today.
The unabridged two volume set is in its third printing (and sells
for well over $100) but the UC Press produced a 350-page abridged edition in
1982 that is a great read for people with a non-technical interest in
rattlesnakes. As of this writing, it is still available for around $20.
This page is maintained by Mike Cardwell