Fellow herpers:
As you all know kingsnakes have long been in decline throughout the
southeast and have been totally extirpated in many areas of Florida where
they were once common such as Paynes prairie. Many other species are in
equally bad shape. The general consensus has long been that fire ants were
the primary cause, along with roads, habitat destruction, and resulting
ecosystem collapse.
There are problems with each of these explanations. Kingsnakes and
other species have disappeared in remote wilderness areas, so it is clearly
not just rednecks, roads, or lack of habitat.
Long ago I noticed that kingsnakes persisted in small numbers on the
islands along the gulf coast. I am told that they persist on dikes in the
everglades too, particularly in agricultural areas, but I have not seen them
there. Kingsnakes still exist in upland locations further north and perhaps
west but I have no personal experience further west. If fire ants were the
problem how could they continue to exist on dikes in the glades? Fire ants
can fly, and I have often seen them on the gulf coast islands, so there goes
that explanation.
If it is a disease there must be either a vector or some other means of
transmission. Snakes are not communal animals so direct transmission is
unlikely. If there was a vector such as mosquitos then the snakes on my back
porch would long ago have died since they can easily be bitten through the
screen. Ditto for an aerosol pathogen.
More recently natricines, once the most common of snakes, have
disappeared too. Our creeks and rivers are now effectively devoid of
watersnakes where there used to be thousands of them, and Steve Christman
has for years offered a reward for anyone who can find a male blue garter
snake. Natricines are extremely prolific. It certainly isn't lack of food
for there are still plenty of small fish.
Let's review what used to be the basic food chain at Paynes prairie:
plants>bugs>frogs>watersnakes>kingsnakes. (Yes, I know
kingsnakes eat things besides watersnakes, and it is true that there was a
catastrophic decline in cotton rats, perhaps caused by fire ants) The point
is that kingsnakes used to eat watersnakes and garter snakes both of which
eat frogs.
Why do the islands serve as refuges? What is different there from the
mainland? Lack of standing fresh water! What needs standing fresh water?
Frogs!
I recently read that ranaviruses have been shown to infect various
reptiles, so I cannot help but suspect that frogs infected the natricines
that infected the kingsnakes. Perhaps the natricines persisted after the
kingsnakes simply because they are more prolific.
The kingsnakes on the gulf islands presumably eat lizards, mice,
possibly birds, and salt marsh watersnakes. Nerodia clarkii is fairly
scarce, lives in brackish water, and thus rarely eats frogs. Likewise
kingsnakes living in upland places like Tennessee probably have less contact
with frog eating natricines than those living further south in swamps.
There are some holes in my theory such as the presumed persistence of
kingsnakes on dikes in the glades where surely there must be plenty of
frogs. Or are there? Is it possible that agricultural spraying in the cane
fields has reduced the number of frogs thus forcing the watersnakes to eat
fish and the kingsnakes to eat the abundant rodents? I don't know.
Moccasins eat frogs and they are doing fine. They have recently been
show to carry eastern equine encephalitis without exhibiting any symptoms,
but that just proves that they are indestructible. Ditto for
bullfrogs.
Even rat snakes are in decline, but there are still some around,
especially large adults. Young rat snakes specialize in small frogs and
lizards whereas the adults do not. I don't know if hylids are susceptible to
ranaviruses or not. Is it possible that their arboreal lifestyle limits
exposure to waterborne disease and thus not all rat snakes have died out
from eating them?
I don't know anything about ranaviruses or other herp diseases, but
cannot help but suppose that the persistence of kingsnakes on small islands
may be an important clue. So who does know about these things?
That is why I am writing this, to see if any of you can point me in the
right direction or have any thoughts on the subject. Feel free to forward
this.
Sleazeweazel