Environmental Engineering Reference
In-Depth Information
Anyhow, they got there, and the giant constrictors eat a lot. Besides deer and the odd alligator, they
hunt down and gobble up raccoons, rabbits, and opossums. Once the Everglades' most frequently seen
species, all three are vanishing fast. A survey of road kill made by park rangers found a decrease of 90
alligators, but they have no previous experience of large constrictor snakes. Birds also make a big part
of what vets find in the stomachs of captured reptiles.
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Meanwhile, a half-hearted and probably doomed hunt is on to eliminate the monsters. This largely
comprises offering prizes to hunters. No doubt the participants have fun, cruising through the swamps
in search of big snakes to shoot. But over ten years, fewer than eighteen hundred have been caught. The
Python Challenge in early 2013, which was entered by sixteen hundred snake-wranglers, bagged just
sixty-eight reptiles. That seems a poor return for a lot of effort. Probably we had best accept that they are
there for good—or until nature thinks differently. As food stocks subside, we should expect python num-
bers to stabilize and start falling. They may settle down to life as one of a range of Everglades snakes
that includes the eastern diamondback, the world's largest rattlesnake and the most dangerous snake in
America.
An estimated quarter of all the animals in the Everglades are exotics. Caribbean and Central Amer-
ican visitors include green iguanas from Puerto Rico, Cuban tree frogs, Jamaican fruit bats, Mexic-
an squirrels, and the odd armadillo from South America. From Africa, there are a bunch of Gambian
pouched rats that escaped from a local keeper on Grassy Key, and around a thousand Nile monitors.
Most of these five-foot-long flesh-eaters are probably also expelled pets.
Then there are the plants. Most of the Everglades used to be treeless. Now the famous rivers of grass
have in many places been replaced by Brazilian pepper trees (
Schinus terebinthifolius
) and Australian
paperbark trees (
Melaleuca quinquenervia
). Both were introduced a century ago to dry out the swamp
and now together cover half a million acres. These are major invasions, with big impacts. But the Ever-
glades has always been an ecosystem in flux, dependent on sea levels. Species have constantly come and
gone. There wasn't a Florida Everglades at all until about five thousand years ago. It has never settled
down to any fixed form, going from mangrove swamps to cypress swamp and hardwood forest and on
to the familiar seas of saw grass, as sea levels rose.
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Species came and went. They still come and go.
The bottom line here is that we should treat species on their merits and learn a little tolerance and respect
for foreigners. They have their idiosyncratic and occasionally disruptive ways, but they add to the vari-
ety of life and often bring benefits. They certainly aren't going away. There are an estimated five thou-
sand alien plant species in US ecosystems, almost a third of the total species count. Florida has nine
hundred of them, and California has three thousand. There have been extinctions among the natives, but
remarkably few. They bring biodiversity, a fact that is rather inconvenient for the many conservationists
who argue vehemently that invaders damage biodiversity. So, in what seems to me extraordinarily Or-
wellian science, they have been trying to define away the issue.
Here is how they did it. In 1997, eleven leading American conservation scientists, headed by Edward
O. Wilson, Daniel Simberloff, Peter Vitousek, and Stanford's Harold Mooney, wrote to US vice presid-
ent Al Gore arguing that “a rapidly spreading invasion of exotic plants and animals . . . is destroying our
nation's biological diversity.” This is not true, but no matter. They argued that to end this nonexistent
loss of diversity, there should be a “national program to combat invasions.”
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