The dodo, poster bird for species extinction, has a pitiful reputation as a stupendously overweight idiot of a bird that couldn't even fly. But scientific evidence is slowly correcting that impression. Its new rep: an evolutionary success, perfectly adapted to its living conditions, thin and relatively fast, but still an early victim to the spread of man.
Animals, such as the dodo, that evolve in isolation frequently exhibit somewhat bizarre traits, and a giant flightless bird is surely on the extreme end of avian evolution. But that doesn't make the dodo a failure. David Quammen, in his seminal book on island biogeography and extinctions The Song of the Dodo, calls the species an evolutionary success; it adapted well to local conditions.
Having reached Mauritius, the birds adapted, probably over several million years, to living on an island that had no predators and a wealth of fruit lying on the ground. They gradually traded their ability to fly for the ability to store larger amounts of fat that would carry them through times of scarcity. To store the fat, they got bigger, making it more difficult to fly. Surrendering the ability to fly, and thus to elude enemies, he says, was an easy trade-off; there were no enemies to flee.
That all ended when the Portuguese and Dutch began arriving in the 16th and 17th centuries. Having no reason to fear man, the big ground-dwelling birds were easy prey. Numerous contemporary accounts describe the birds as trusting and friendly—hardly bothering to get out of the sailors' way, never mind trying to run and hide. But that was ecological naiveté, says Quammen, not stupidity.
Although hunting certainly reduced populations, it was the animals the sailors brought with them, especially pigs, rats, and monkeys, that delivered the death blow to the species by preying upon their eggs and chicks, if not the adults.
And while the dodo was definitely a big bird, it probably wasn't nearly as fat and geeky as has been depicted. Most of what is known about what the dodo looks like is derived from paintings and caricatures from the 17th century.
Andrew Kitchener, a biologist and curator at the Royal Museum of Scotland, has shown that the dodo was probably much thinner and more lithe than has generally been depicted. Most of the sketches and paintings were copies, not based on original observations. Some may be based on birds in captivity in Europe that were unintentionally overfed, and fattened up beyond what would occur in nature.