The Galapagos proved such a fertile field laboratory for Darwin, as well as for the generations of scientists to follow, because all plant and animal life arrived by wind and current and evolved insulated from human incursion. In addition, as a result of the islands' isolation from each other, diverse species emerged.
At the same time, the lack of natural predators led to the animals' fearlessness.
By the time the park was established in 1959, however, predators introduced by humans were proliferating. A year later, conservation groups established the Charles Darwin Research Station on Santa Cruz to spearhead preservation and educational efforts and supervise scientific endeavors. And, on many fronts, progress has been made.
An effective breeding program has the giant tortoises multiplying again. Abundant colonies of sad-eyed fur seals frolic offshore.
Authorities have undertaken successful campaigns to eradicate hundreds of feral goats, which were introduced to serve as fresh meat but which also wiped out much of the native vegetation on some islands.
Rats, which attack penguin chicks and tortoise eggs and hatchlings, have nearly been eliminated on Pinzon Island. Wild dogs no longer threaten land iguana populations.
In 1986, the waters surrounding the islands were declared a Marine Resources Reserve. And last year, after an outcry by naturalists over the slaughter of sharks for their fins, primarily by Asian fishermen, a law was passed prohibiting shark and gill-net fishing.
Even the ferocious-looking white-tipped sharks have returned to the southern beach of Bartolome Island, where they glide 10 abreast in water so clear and shallow they can be seen from the shore. They had been scared away by people until swimming was prohibited.
In general, Galapagos wildlife is so benign to visitors, said guide Julian Echeverria, that "there's more danger of breaking a leg embarking from the dinghy than of being attacked by an animal."
Rather, it is the behavior of humans that concerns conservationists.
"Ten tourists, if they behave badly, could easily destroy the Galapagos," says the Wildlife Fund's Kramer, a former Darwin Foundation president, "whereas, 80,000 could be fine if they are well-managed."
Examples of such indiscretions abound. Only last August, in a bid to lure hammerhead sharks, one visitor threw out a fishing line, snaring a giant frigate bird with the hook and entangling another in the line.
Another tourist trampled on sea turtle nests along a secluded sandy beach. Others in his group frightened nearby animals by making loud noises and motioning with their hands.
A young sea lion on Seymour Island was found with a piece of twine around its neck--a plaything that could become a deadly noose. Even touching a young sea lion is taboo: It alters the pup's scent and could prompt its mother to reject it, resulting in its starvation.
But for the respectful nature enthusiast, the opportunity to view so many kinds of rare animals at such close range in such striking settings remains nothing short of remarkable.
"The tourists who come here now," quipped a tour boat purser, "they are all little Darwins."
On Hood Island, Ian Noble wanders along the rugged volcanic landscape surrounded by creatures he previously had only dreamed of. He had journeyed from Africa to the Amazon in search of unusual birds, but now he has entered an avian haven unlike any other.
Scores of blue-footed boobies--which, one writer quipped, prove that God has a sense of humor--whistle and honk in their seriocomic mating dance, high-stepping with their bright blue feet as though strutting with flippers. Colonies of snow-white masked boobies atop black lava cliffs peer at Noble like ornithological Zorros.
Rare waved albatrosses practice their courtship ritual--stretching their necks, opening their long beaks in a V to emit a high-pitched "whoo-oo," then ducking down to engage in an intense, clattering round of beak-jousting with their training mate.
And, all along the coastline, prehistoric-looking marine iguanas, miniature Godzillas, provide a creepy reptilian backdrop to the bird riot.
"I'd always heard that the Galapagos were a paradise for bird-watchers," Noble confides as he steps around boobies, booby nests and booby chicks along the rocky trail. "But I \o7 never \f7 expected anything like this."