The Enigmatic Dodo
The following is a textual transcription of the Dodo account in the book “The Annihilation of Nature: human extinction of birds and mammals” by Ceballos et al (2015, John Hopkins Press, Baltimore). Available at John Hopkin’s Press and Amazon.
Among birds that went extinct early, the dodo has become the icon of extinctions. It was a ridiculously awkward-looking bird, found only on the island of Mauritius in the Indian Ocean, approximately 870 kilometers (540 miles) east of Madagascar. A Dutch sailor named Heyndrick Dircksz Jolinck, who visited the island in 1598, first described the dodo. He wrote of a large bird with pigeon-sized wings that were useless for flying. He noted, “these particular birds have a stomach so large it could provide two men with a tasty meal and was actually the most delicious part of the bird.” But other contemporary reports of dodos indicated that their meat tasted bad and was tough. Nonetheless, easy meat was going to be eaten by hungry sailors, so the crews of ships that landed on Mauritius slaughtered and ate large numbers of the defenseless dodos.
Much of what is known today about how dodos looked comes from drawings and paintings of an obese and clumsy bird. However, some of the sketches by illustrators may have been of an overfed captive bird. At least one illustration dating back to the 1500s depicts them as slim. Because Mauritius has marked dry and wet seasons, it is possible that dodos fattened themselves on ripe fruits during the wet season and lived on fat reserves during the dry season when food was scarce. Dodos also may have accumulated body fat for breeding activities, then lost that fat over time.
The dodo was certainly a large bird. It had a huge bill, gaping nostrils, and bulging eyes. Its tail was a clump of feathers positioned high on its back. Adult dodos probably stood about 1 meter (1 yard) tall and weighed as much as 20 kilograms (44 pounds). They nested on the ground and fed on vegetation. Their large beaks seemed to be adapted for shelling and eating fallen fruits or breaking up the roots of plants. It is possible that the horny covering on the beak was shed during non-breeding periods.
Dodos (or the species that evolved into dodos) had been on Mauritius for several million years and evolved, like so many island birds, in the absence of predators. It was their Eden, with abundant fruits scattered on the ground. Dodos were a classic example of animal adaptation to remote island life. The sailors reported they had no fear of people, and this trait was part of their undoing. It is likely, however, that many factors contributed to the demise of the dodos, in addition to hunting by humans. There was also predation on their eggs by introduced species (rats, pigs, and crab-eating macaques), habitat change caused by introduced species such as goats, and perhaps even natural disasters such as cyclones and floods--disasters they might have well survived in their formerly pristine environment. To put it another way, many of the factors that threaten birds today likely ganged up on dodos and spelled their doom.
The last confirmed sighting of a live dodo was in 1662, less than a century after the bird’s discovery by Europeans. Today, we don’t even have a taxidermy specimen to study. The last stuffed dodo, stored in Oxford University’s museum, was destroyed around 1755 because of its deteriorating state. Only a partial skeletal foot and the head were saved from that specimen, and these fragments include the only soft tissue remains of the species.
An endemic tree in Mauritius, Tambalacoque, is known as the dodo tree. A long-lived species, it has highly valued timber and fruit resembling a peach. In 1973 it was on the verge of extinction, with only about 13 individuals left, each estimated to be about 300 years old. In 1977 it was hypothesized that this tree would disappear because its seeds could germinate only after passing through the digestive tract of a dodo. If so, the dodo and its tree would have been a remarkable example of coevolution. But there is now evidence of germination by the tree long after dodos were exterminated and the possibility of effective seed dispersal by existing species such as fruit bats and parrots. Still, one cannot help but look at the dodo tree and wonder what the scene would have been like with dodos sitting in its shade.
The dodo for most of its lifespan had very few predators which meant it had no fear of humans when eventually discovered, and were thought have also been eaten by slaves and fugitives, the dodo’s nests were plundered. The nests were also destroyed to allow habitation of humans in the forests they once lived.
The dodo was endemic to Mauritius island in the Indian Ocean, some 2000 km off the coast of Africa and Madagascar. Mauritius is now a country, and its population is more than 1.2 million people. The island is covered by lush tropical vegetation; some of the original vegetation is gone.
The dodo became extinct due to overexploitation by sailors that visited the island to get food and freshwater, and introduced domestic animals such as goats and rats that either destroyed the vegetation or preyed on the dodo eggs.