The dodo was a large flightless bird native to the island of Mauritius, located in the Indian Ocean. The first birds were seen around 1600, and less than 100 years later, they were entirely extinct. Many people like to use the animal as an archetypal example of an extinction event caused by humans, cautioning that other animals could go the way of the dodo without prompt action to protect endangered and threatened species.
According to surviving specimens, research on Mauritius, and numerous contemporary accounts, the dodo appears to have been around 3 feet (1 meter) tall, with grey plumage, white markings, and a heavy hooked beak. The birds were closely related to pigeons, sharing the squat body and stubby legs. Several skeletons are held in natural history museums, and some museums have built models to show visitors what the birds might have looked like.
Dodos were apparently very gentle, friendly birds. This is probably the result of evolving in an isolated island environment without any predators; many island animals suffer greatly when humans enter their environment, introducing new and previously unknown concepts to their world like guns, rats, and cats. Many people considered the bird to be stupid, because they were so friendly, and the term “dodo” is sometimes used to describe someone who is particularly dopey, although this is probably a bit unfair.
The extinction of the dodo was probably caused by a number of factors. First of all, sailors ate them when they visited the island, hunting the slow, friendly birds quite easily. Apparently, the meat didn't taste very good, but this obstacle was minor to hungry, bored sailors. Humans also introduced cats and rats, who preyed on the gentle bird, along with goats, which damaged the ecosystem that had evolved on Mauritius. These combined factors proved to be too much for the highly specialized bird, and it vanished.
The dodo was probably not the first animal to go extinct because of human activities — and it certainly wasn't the last — but in the 20th century, the case began to be explored more closely in the hopes of learning more about extinction events and warning signs that could be heeded in the future. Today, a complex system is used for classifying animals as threatened or endangered, and these animals are closely regulated in the hopes of preventing further human-caused extinctions. Increasing human populations are putting immense pressure on the global environment, however, and the rate of extinction is likely to increase, despite the best efforts of many conservationists.