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