Was the Dodo a Pigeon? The Dodo's Closest Relatives

How scientists worked out that the dodo was a pigeon

For two centuries after the dodo was discovered, nobody was sure what kind of bird it was. Naturalists called it a small ostrich, a rail, an albatross or a kind of vulture. The confusion was understandable: the dodo was large, flightless and had a huge hooked beak, and very few specimens had reached Europe.

In 1842 the Danish zoologist Johannes Theodor Reinhardt studied a dodo skull in Copenhagen and suggested it was a ground pigeon. Many scientists laughed at the idea, but in 1848 the English naturalists Hugh Strickland and Alexander Melville published The Dodo and Its Kindred, a detailed study of the Oxford head and foot and other remains. They concluded that the dodo and the Rodrigues solitaire were closely related to each other and that both were pigeons.

The final proof came from DNA. In 2002, a team led by Beth Shapiro extracted DNA from a dodo leg bone at Oxford and from a solitaire bone, and compared it with many living pigeons. The results confirmed that the dodo and solitaire sit firmly within the pigeon family, nested among island ground pigeons from Southeast Asia and the Pacific.

Which features show the dodo was a pigeon?

Strickland and Melville pointed to a list of features shared with pigeons and with no other birds. Later studies of skeletons have added more.

• Beak structure: a short, hard tip at the end of a long, softer base, with the nostrils set low in the middle of the beak, as in pigeons.
• Bare skin around the eyes, reaching almost to the beak, which many pigeons also have.
• Leg bones and scales most similar to those of ground-dwelling pigeons.
• A large crop, the food pouch in the throat that pigeons use to store food and produce “crop milk” for their chicks.
• A single egg, according to one 17th-century account, in line with the very small clutches typical of pigeons.
• Skull details such as the shape of the palate and jaw.

Despite its size, many parts of the dodo’s skeleton remained very similar to those of smaller, flying pigeons. The main differences were its tiny wings, heavier legs and enormous beak.

The dodo’s family tree

The dodo and the Rodrigues solitaire (Pezophaps solitaria) formed their own small group within the pigeon family. The solitaire lived on Rodrigues, about 560 km (350 miles) east of Mauritius, and was even taller than the dodo: males stood up to about 90 cm (35 in) and weighed up to about 28 kg (62 lb). It was hunted and harmed by introduced animals and was extinct by the late 1700s.

Their closest living relatives are a group of mostly ground-loving island pigeons:

All of the familiar pigeons and doves, from the rock pigeon of city streets to the mourning dove, are more distant cousins in the same family. In everyday English, “pigeon” and “dove” are used loosely for the same birds, as our guide to dove vs pigeon explains.

How did a pigeon become a dodo?

The 2002 DNA study suggested that the dodo and solitaire lineage split from its relatives around 23 million years ago. Mauritius and Rodrigues are volcanic islands that are much younger than that, so the dodo’s ancestors must have kept the ability to fly for a long time, probably hopping from island to island across the Indian Ocean from South or Southeast Asia.

Pigeons are excellent long-distance colonists of islands. The Nicobar pigeon still flies between small islands, and pigeons have reached remote islands all over the Pacific and Indian oceans. When a group of flying pigeons settled on Mauritius, they found an island with abundant fallen fruit and seeds and no ground predators or large plant-eating mammals to compete with.

Over many generations, natural selection favored larger birds that could eat bigger fruits and store more fat, and flight became an unnecessary cost. Wings and breast muscles shrank while legs and beaks grew stronger. This pattern, called island gigantism combined with flightlessness, has happened many times in other birds, such as the moas of New Zealand and the elephant birds of Madagascar. You can see more examples in our list of flightless birds.

Did other giant pigeons exist?

The dodo was not the only pigeon to grow huge on an island. The Viti Levu giant pigeon (Natunaornis gigoura), known from bones found in Fiji and described in 2001, was a flightless ground pigeon only slightly smaller than the dodo. It probably disappeared after people reached Fiji, although the timing is uncertain.

These extinct giants show how readily pigeons adapt to island life, and how vulnerable they became once humans and introduced animals arrived. Today, scientists are studying the Nicobar pigeon as a possible starting point for recreating a dodo-like bird, a project explained in Could the dodo be brought back?