#raphinae

Island Weirdness #24 -- The Dodo

Out of all the extinct island species we’ll be covering in this theme, there’s probably none more famous than the dodo (Raphus cucullatus) -- a large flightless pigeon about 1m tall (3′3″).

The island of Mauritius was formed from a volcanic hotspot in the Indian Ocean about 10-7 million years ago, in a location roughly 1000km east of Madagascar (~620 miles). The dodo’s smaller flying ancestors must have arrived there sometime after that point via island-hopping from Southeast Asia -- the area where its closest living relative the Nicobar pigeon is still found today -- and finding themselves in an ecosystem completely lacking terrestrial mammals they quickly evolved to fill a large herbivore niche.

Although frequently depicted as blue-grey, the dodo’s actual life appearance is unknown for certain. No complete preserved specimens have survived into the present day, and contemporary accounts and drawings are somewhat inconsistent -- but common elements among them suggest it was more of an earthy brown, with cream-colored primary feathers, yellow legs, a naked pale face, and a green-and-yellow streaked beak. The large white ostrich-like tail plumes shown in many images have also probably been highly exaggerated, since older images depict the dodo with only a tiny tufted tail at best.

Its appearance probably also varied based on the time of year, molting its feathers at the end of summer and being fattest during the breeding season in early spring.

And despite often being stereotyped as a slow dim-witted animal, the proportions of the dodo’s leg bones suggest it was actually quite fast and agile. Its brain-to-body size ratio was also typical compared to other pigeons -- which are known to be highly intelligent birds -- and it had a well-developed sense of smell.

Sadly this fascinating bird disappeared within only a century of being discovered by humans in the late 1500s. Its “island tameness” due to its lack of natural predators made it easy prey, its forest habitat was rapidly destroyed, and introduced mammal species (such as dogs, pigs, cats, rats, and macaques) competed for its food sources and ate its eggs and young -- pressures that its population simply couldn’t hope to recover from all at one.

Its loss wasn’t even properly recognized until much later in the 1800s, but since then it has ironically become immortalized as a icon of human-caused extinction.

Island Weirdness #28 -- The Rodrigues Solitaire

Located to the east of Mauritius, the small island of Rodrigues is the geologically youngest of the Mascarenes, formed only about 1.5-2 million years ago.

And it also had its own large flightless bird -- the Rodrigues solitaire, Pezophaps solitaria.

It was closely related to the dodo, although it wasn’t a direct descendant. Based on DNA studies their last common ancestor is estimated to have lived about 20 million years ago, so they must have each convergently evolved from separate pigeon lineages that arrived on each island at different times.

Standing 70-90cm tall (2′4″-2′11″), with males being larger than females, it had long legs, a long neck, and a slightly hooked beak with a black band described as resembling a widow’s peak. Its plumage was grey and brown, and it was reportedly aggressively territorial and capable of giving a strong bite.

It had large lumpy bony knobs on its wrist bones that were used as weapons to clobber each other while fighting. Due to this its wings were less reduced than the dodo, retaining stronger musculature, and it was apparently also capable of using them to create loud low-frequency sounds for communication -- possibly in a similar manner to modern crested pigeons’ whistling wings.

The solitaire survived for longer than both its dodo cousin and the Réunion ibis, but only because its island was rarely visited by humans until the late 1600s. Once Rodrigues began to be exploited the story became the same as the other Mascarene islands: a combination of hunting, habitat destruction, and predation by invasive species rapidly dwindled its population. It likely went extinct sometime between the 1730s and 1750s, since an exhaustive search for a live specimen in 1755 failed to find a single bird.

Neoteny in subfamily Raphinae. Dodo (Raphus cucullatus) and Rodrigues solitaire (Pezophaps solitaria) compared with juvenile wood pigeon (Columba palumbus).