I am interested in learning the differences between the Northern
Pacific Rattlesnake and the Southern Pacific Rattlesnake, especially
as it pretains to venom. Also information as to the range of thses
snakes and if there is any overlap between the two sub species.

Dear bonron13-ga;

Thank you for allowing me an opportunity to answer your interesting question.

The Southern Pacific Rattlesnake (Crotalus oreganus helleri) and the
Northern Pacific Rattlesnake (Crotalus oreganus oreganos) are both
subspecies of the Western Rattlesnake.

CALIFORNIA HERPS.COM
http://www.californiaherps.com/snakes/pages/c.o.helleri.html
http://www.californiaherps.com/snakes/pages/c.o.oreganus.html

Both of these snakes are vipers and they are dangerously venomous, as
snakes native to the United States go. The two snakes are
superficially similar to one another except for the distributions and
minor differences in the body and tail coloration and patterning. The
Southern is typically darker and the pattern is less defined than that
of the lighter and more detailed Northern variety.

The Southern Pacific Rattlesnake is distributed in its native United
States, in Southwestern California and also in Western Baja California
(Mexico).

VENOMBYTE
http://www.venombyte.com/venom/snakes/southern_pacific_rattlesnake.asp

The Northern Pacific Rattlesnake is the only venomous species native
to Northern California. It is distributed along eastern Washington
(State) east to western Idaho, south through eastern Oregon into
northern California. In Canada it is also found in South Central
British Columbia.

VENOMBYTE
http://www.venombyte.com/venom/snakes/northern_pacific_rattlesnake.asp

CALIFORNIA POISON CONTROL
http://www.calpoison.org/public/cvmap.gif



The overlapping distribution areas of these two snakes are obviously
located in the State of California where their habitats share a common
region.

So let?s talk about venom for a moment. Where venom is concerned both
species are commonly characterized as the Western Rattlesnake with
very little (if any) reference to other subspecies individually. They
are equally venomous and once bitten, no matter which one is the
villain, the victim is in serious trouble unless he receives
relatively prompt medical treatment:

 ?Venom primarily hemorrhagic (affecting blood) but some subspecies
contain neurotoxic components. Toxicity of venom is greater than some
larger species such as the western diamondback. This coupled with the
high irritability of some individuals makes this a dangerous snake.
Hemorrhagic, neurologic and proteolytic activity can all result from
the same bite. Hemorrhagic activity in 18 minutes accompanied by some
paralysis. Death in untreated cases may occur in 18 hours or up to 5
days. Lethal venom dose for humans is 70-160 mg and adults can produce
up to 112 mg of venom (dried). Dried venom toxic to mice for at least
27 years.?

VENOMOUS SNAKES
http://www.envtox.ucdavis.edu/CEHS/TOXINS/venomsnakes.htm

I hope you find that my research exceeds your expectations. If you
have any questions about my research please post a clarification
request prior to rating the answer. Otherwise, I welcome your rating
and your final comments and I look forward to working with you again
in the near future. Thank you for bringing your question to us.

Best regards;
Tutuzdad ? Google Answers Researcher


OTHER INFORMATION SOURCES

SOUTHERN PACIFIC RATTLESNAKE
http://www.corallus.com/prismreptiles/projects-cohelleri.html

SAN DIEGO NATURAL HISTORY MUSEUM
http://www.sdnhm.org/fieldguide/herps/crot-vir.html

WILDHERPS
http://www.wildherps.com/species/C.oreganus.html
http://www.wildherps.com/species/C.oreganus.html#oreganus
http://www.wildherps.com/species/C.oreganus.html#helleri

CALIFORNIA POISION CONTROL
http://www.calpoison.org/public/rattler.html

VENOMOUS REPTILES.ORG
http://www.venomousreptiles.org/forums/Experts/5301

WESTERN RATTLESNAKE NATURAL HISTORY
http://darkwing.uoregon.edu/~titus/herp/viridishistory.htm





SEARCH STRATEGY


SEARCH ENGINES USED:

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SEARCH TERMS USED:

Western rattlesnake

Pacific rattlesnake

Southern pacific rattlesnake

Northern pacific rattlesnake

Habitat

Distribution

Toxicity

Venom

Poison

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Request for Answer Clarification by bonron13-ga on 08 Apr 2005 10:38 PDT

Thanks for the response.  Do you have any idea how far north, in
California, the Southern Pacific ranges and vice versa?

---

Clarification of Answer by tutuzdad-ga on 08 Apr 2005 11:38 PDT

Based on these small maps it?s difficult to tell precisely where one
species becomes rare the other more prevalent:

Northern Pacific Rattlesnake distribution area
http://www.corallus.com/prismreptiles/map-cooreganus.html

Southern Pacific Rattlesnake distribution area
http://www.corallus.com/prismreptiles/map-cohelleri.html

Suffice it to say that there is obviously an overlapping area of
habitation along a line common to Central California. How wide that
area is seems to be unknown for certain or at the very least
insignificant of discussion.

According to this document it seems that Canadian officials may have a
much more detailed grasp about the range of these animals:

?The nominate species, ?C. viridis? has an extensive range covering
most of Western North America. The range of ?C. v. oreganos?, extends
from Southern British Columbia, through Central Washington, Oregon and
into Central California?within British Columbia  ?C. v. oreganos? is
found throughout the Okanagan Valley west along the Thompson Valley
Plateau as far as Lillooet and east as far as Grand Forks?.?

STATUS OF NORTHERN PACIFIC RATTLESNAKE IN BRITISH COLUMBIA
http://wlapwww.gov.bc.ca/wld/documents/statusrpts/wr54.pdf

I hope this helps.

Regards;
Tutuzdad-ga

Hi. Perhaps this will help.

FIG. 1. The distribution of the currently recognized subspecies of
Crotalus viridis (after Klauber, 1972).
FIG. 2. Sampling localities for C. viridis.
"...These mountain chains now form firm barriers between the two
regions with the exception of a pass in the Sierra Nevada Mountains in
Northeast California through which there may be limited gene flow
between C. v. oreganus (northern Pacific) and C. v. lutosus (Great
Basin)..."
http://biology.bangor.ac.uk/~bss166/Publications/PookViridis.pdf

Regards,
hummer

Check out a copy of Carl Ernst's "Venomous Reptiles of North America"
- there's a pic of the cover on http://www.envenomated.com