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Posted by David L. Martin on July 11, 2002 at 19:38:21:
In Reply to: Back to your earlier post.... posted by Byron Larkin on July 10, 2002 at 11:36:17:
And you bring up another interesting point. What
is the main reason for the decline of the adamanteus
population? Many people look at the "large"
tracts of "good" habitat today and wonder why
rattlesnake populations aren't what they once
were. There is a world of difference between
the "protected" areas of Florida today and the
vast tracts of the early twentieth century,
through which a few cars typically traveled on
very sparse roads at no more than 30 mph. Look
at Payne's Prairie. It's still there, very much
intact. What happened to all the snakes? To me,
it is all about road density, traffic levels, and
car speed. We know from telemetry studies that
road mortality is one of the main sources of
mortality on adult adamanteus, perhaps the single
biggest one. People tend to focus on the
habitat, rather than the roads themselves and
the traffic levels. You say adamanteus has a
"small" home range. Adult males average
400-600 acres, and these are your run-of-the-mill
4-5 footers. To my knowledge no one has ever
telemetered a 6-foot adamanteus. Since a
6-footer is twice the mass of a 5-footer,
it is reasonable to suppose that it has double
the home range size. This is over a square mile! Combine
this with the fact that adult males routinely
move 1/4-1/2 mile at breeding time. Again, these
are 4-5 foot males.
If we accept the fact that South Texas still
produces 7-foot atrox (and I assure you it does),
while Florida does not produce 7-foot adamanteus,
we must ask why. I do not believe it is a growth
issue. My data indicate that South Texas atrox
do not even grow as rapidly as North Florida
adamanteus. There is every reason to think that
South Florida adamanteus grow even faster. The
atrox would have to grow considerably faster to
account for the large number of 6-7 foot snakes,
which we agree is a rare size class indeed among
adamanteus today.
On the other hand, on a good spring night I can
find 30-40 atrox in Hidalgo or Starr County,
simply by road cruising. On large, generally
inaccessible ranches the number can be even
higher. How many adamanteus can you find on a
good day by similar methods? In any part of the
range, including these "protected" areas? All
of the prime adamanteus habitat has been
crisscrossed with a network of roads of every
description, and a steadily increasing traffic
flow. I estimate that there are 1 million atrox
in Hidalgo County alone at this moment. Locked
gates are seen everywhere, preventing public
access to huge areas of the landscape. Kenedy
County is almost a million acres, 90% of which
is TOTALLY inaccessible to the general public.
Who knows how many atrox are there? 30 million
seems like an underestimate. Such numbers are
required to produce a few monsters, which have
always been a tiny fraction of the population in
both species.
I can assure you that the 7 ½ foot captive-raised
adamanteus I saw in Tallahassee was no legend.
The species is physiologically capable of
reaching impressive size.
And for you, Steve:
David L. Martin
Head Keeper, Department of Herpetology
Gladys Porter Zoo
