The extinct dodo bird, Raphus cucullatus, was a large, flightless bird endemic to the island of Mauritius in the Indian Ocean. A member of the pigeon and dove family (Columbidae), its closest living relative is the Nicobar pigeon. The dodo’s inability to fly and its rapid disappearance after human contact have made it an international symbol of extinction.
Evolutionary Reasons for Flightlessness
The dodo’s flightlessness was a direct result of adapting to its unique, isolated island environment. When the ancestors of the dodo arrived on Mauritius, they found an ecosystem completely devoid of terrestrial mammalian predators. The primary evolutionary pressure to fly away from danger was therefore removed, making the energetic cost of maintaining flight capability unnecessary.
The island also provided an abundance of food resources, such as fallen fruits and seeds, that were easily accessible on the forest floor. Since there was no need to forage widely by air, the dodo’s body structure began to change over generations. This shift led to the loss of a large, muscular keel on the sternum, which is the anchor for powerful flight muscles in flying birds.
Without the constraints of flight, the birds grew larger, a phenomenon known as island gigantism. This allowed the dodo to allocate energy away from developing wing structures and toward other functions, such as reproduction or survival. Its large size and heavy body, which could weigh between 10.6 and 17.5 kilograms, made flight physically impossible.
Physical Characteristics and Habitat
The dodo was a sturdy bird, standing approximately 65 to 75 centimeters tall. Its physical appearance, known primarily through 17th-century illustrations, depicted it with brownish-grey plumage and a grey, naked head. It possessed a large, distinctive, hooked beak, up to 23 centimeters in length, which it likely used to consume fruits and seeds.
The bird’s legs were robust and strong, allowing it to move nimbly across the forest floor. Subfossil remains suggest the dodo primarily inhabited the woods in the drier coastal areas of Mauritius. It was a ground-nesting bird, laying a single egg on the forest floor.
The Rapid Extinction
The dodo’s isolated existence ended with the arrival of European sailors, specifically the Dutch, in 1598. The bird’s natural lack of fear toward humans, a trait developed in a predator-free environment, made it easy prey for sailors seeking fresh meat. However, direct human hunting was not the sole, or even the most significant, driver of its demise.
The far greater threat came from the invasive species introduced by the settlers, including rats, pigs, monkeys, and dogs. These animals preyed upon the dodo’s single egg and vulnerable chicks in their ground nests. Habitat destruction due to logging and clearing for human settlement further accelerated its decline by removing its food source and nesting grounds.
This combination of factors caused the population to collapse rapidly, making the dodo one of the most well-documented cases of human-caused extinction. The last widely accepted sighting occurred in 1662, meaning the species vanished less than a century after its discovery by Europeans. Although modern analysis suggests the extinction date may have been slightly later, around 1693, the rapidity of its disappearance remains a stark reminder of the vulnerability of island species.