It was the humble finch. Darwin discovered an amazing variety of finches, each uniquely adapted to its surroundings on the various islands of the Galapagos. He theorized that the birds had common ancestors but evolved differently depending on their local habitat. The long-beaked Great Frigate puffs out his red chest. Since the animals and birds have no fear of humans, Darwin was able to observe at close range.
Modern visitors can do the same.
This tameness remains despite several centuries of visits by pirates, whalers, a host of eccentrics and Robinson Crusoe types who lived off the tortoises, land iguanas, birds and fish. The Galapagos consists of 13 major volcanic islands that vary dramatically in terrain and in the type of wildlife they harbor. When you've seen one, you definitely have not seen them all. On the Galapagos Island the tortoise has no fear of humans. Park rules are strict and the number of visitors controlled.