One of the more interesting places to visit is Ilha da Queimada Grande, a 106 acre island off of the coast of Brazil. It is often called "Snake Island" in deference to the population of golden lancehead vipers thereon--a reptile found nowhere else in the world, although the deadly jararaca is related and probably was a distant ancestor. "Population" is perhaps too mild a word. "Writhing carpet" or "sea" of serpents would probably be more appropriate, with some observers claiming a density of one snake per square yard of the island. Even if this figure turns out to be exaggerated, there is no doubt that the island contains the highest concentration of dangerous reptiles in the world.
The island had originally been part of the mainland millions of years ago but eventually became separated and isolated. When it did so, there were no natural enemies of the snakes left on it, so they multiplied profusely. Normally, an unchecked population of critters will run out of food and thus limit its numbers by starvation. In this case, however, a constantly replenishing source of migratory birds keeps a huge quantity of the reptiles happy and well-nourished.
However, as previously noted in "Rattlesnake Lunchtime Rituals" in Henry's Daily Factoids, venomous snakes have trouble catching birds, as a bitten fowl can often fly a considerable distance before the venom takes effect. This problem, from the snake's point of view, is exacerbated when the encounter takes place on a small island, as the prey will probably be fleeing over the ocean before it succumbs. Evolution solved this dilemma for the golden lancehead vipers by making their venom extra-toxic so that the birds collapse immediately and cannot make it off of the isle. As a result, these vipers' poison is three to five times more powerful than that of any reptile on the mainland and can literally dissolve human flesh almost instantly.
Fans of Indian Jones and the Temple of Doom will recall the crunching sounds from the scene where the good guys had to pass through a tunnel whose floor was covered with a layer of live bugs and insects. In addition to the snakes, Ilha da Queimada Grande is overrun with cockroaches, and anyone passing through the woods will produce the same audible effects as they tread upon the 100-acre rug of bug.
While I mentioned that the isle would be an interesting place to visit, such a trip is unlikely for all but a few. The Brazilian government bans anybody from entering the island except for specially selected scientific sorties by folks with things like "Ph.D" in their titles. There once was a lighthouse keeper and his family living there, but, purportedly, an unfortunate event involving the local reptilian fauna motivated the conversion of the lighthouse to an automated one in the 1920s.
Ironically, despite their high local population and successful lifestyle, the golden lancehead viper is one of the most endangered snakes in the world. Because of their concentrated numbers in such a small area, it would take only one really bad forest fire or epidemic to wipe out the entire species. In addition, their numbers have been decreasing due to reptile smugglers who realize that a single one of the vipers can fetch $30,000 on the black market to pet collectors or pharmaceutical laboratories. Furthermore, because of their limited geographical range, the snakes are subject to intense interbreeding and lack of genetic diversity. This situation results often in sterile progeny as well increased chances of susceptibility to diseases.
Yuck--in all respects!
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