Raphidae

(vertebrate zoology) A family of birds in the order Columbiformes that included the dodo (Raphus calcullatus); completely extirpated during the 17th and early 18th centuries.

(Raphidae)

Class: Aves

Order: Columbiformes

Family: Raphidae

Thumbnail description
Large, stocky, flightless birds

Size
40 in (100 cm); 24–40 lb (10.5–17.5 kg); some estimates up to 50 lb (22.5 kg)

Number of genera, species
2 genera; 3 species

Habitat
Woodlands

Conservation status
Extinct

Distribution
Mascarene Islands

Evolution and systematics

The Mauritius dodo (Raphus cucullatus), Rodrigues solitaire (Pezophaps solitaria), and the Réunion solitaire (Raphus soliatrius) were three very large, flightless birds usually treated taxonomically as constituting the family Raphidae within the order Columbiformes. In their isolation on the Mascarene Islands, 500 mi (800 km) east of Madagascar, these aberrant pigeons evolved gigantism and flightlessness in the absence of native ground predators. Their existence has been documented in journal accounts and, in the case of the dodo and Rodrigues solitaire, in illustrations made by eyewitnesses as well as from skeletal material that has been excavated and examined in detail.

Masauji Hachisuka, in his extensive monograph on these species, reports about 20 firsthand accounts that mention the dodo, and evidence exists of 16 live dodos that were exported to Europe, India, or Japan. The dodo first appeared in the journals of Dutch Admiral Jacob Cornelius Van Neck in 1598 (published in 1601), who described dodos (in translation) as "larger than the swan, having the body of an ostrich, the feet of an eagle, few feathers on the body, the wings like a teal's." Among the more extensive accounts of the dodo, and perhaps also the last report of this species in the wild, is that of Volquard Iversen, who was shipwrecked on Mauritius for five days in 1662. Skeletal remains of dodos have been found in alluvial outwashes in bogs on the island. One mounted specimen reached Europe and was mentioned in a 1656 publication, but this specimen was burned in 1755 and only its head and right foot were saved. The left foot of another individual exists in the British Museum and another head in the Zoological Museum of Copenhagen.

More is known of the Rodrigues solitaire. The journal of François Leguat describes this species' behavior in a rather extensive account written when he and eight others inhabited Rodrigues for two years, from April 3, 1691 until May 21,1693. Specimen records of solitaires are more extensive than those of dodos; over 2,000 solitaire bones were found in caves on the island between 1864 and 1875.

The existence on Réunion of another species of solitaire has been inferred only from contradictory travelers' accounts; no illustrations exist of this bird, nor have any raphid skeletal remains been found. This "solitaire" may actually have been an ibis (genus Threskiornis), as arguments attempt to reconcile skeletal remains found in the 1990s with the meager description of Réunion's "solitaire" by Sieur DuBois in 1669. This Réunion bird was described as a solitary bird, rarely seen, that inhabited remote mountain forests, fed on worms and soil insects, flew "but very little," and had a bill "like that of a Woodcock but larger." Nothing is known of its breeding. It was considered frequent in 1705 but disappeared suddenly thereafter and was last reported being seen in 1708.

While, at first glance, the Raphidae appear unlike pigeons, they are actually very close to them anatomically. Hence, both the pigeons (Columbidae) and the Raphidae are placed in the order Columbiformes. The dodo's big hooked bill is fore-shadowed by the enlarged bill tips seen in most pigeons, and the skeletons of the dodos and pigeons are similar given the dodo's adaptation to flightlessness. Dodo feathers were identical to pigeon feathers and the loose plumage is like that seen in young squab. In fact, it is now generally agreed that the dodos are an example of neotony or paedomorphosis—the retention of juvenile characters into adulthood. Derived from pigeon-like stock, the dodos lost their wings, developed gigantism, and retained juvenal plumage and body form.

Physical characteristics

These birds were all about the size of a turkey, were heavily built, and possessed much reduced wings, strong feet, and a strong bill. The dodo had a featherless face, and its plumage was represented as bluish or brownish gray in paintings. Its bill was heavy and hooked and bore transverse ridges; possibly the bill's rhampotheca (horny sheath) was molted seasonally. Compared with the dodo, the Rodrigues solitaire was taller and more slender, with a smaller head and a slighter bill, metacarpal wing spurs, and largely brownish plumage.

John Tenniel's illustrations of the dodo in Lewis Carroll's Alice's Adventures in Wonderland express the traditional image of a dodo: a fat bird with a clumsy shape, a very large head, a heavy hooked bill, and a little tail of curly feathers. This characterization of the dodo may not be accurate. In 1993, Andrew Kitchener presented several arguments for a thinner dodo. He noted that drawings made before 1620 (by individuals who had seen these birds on the islands) showed thinner birds than did illustrations made after 1620 (which were done mostly in Europe). The very fat birds depicted in illustrations likely represent individual captives in Europe. Traditional descriptions of size emphasize Thomas Herbert's estimate (in 1634) of dodo body mass at 50 lb (22.7 kg), but estimates of body mass based on scale models, skeletal mass, and various scaling relationships show the dodo as a normally "thin" bird (about 23–39 lb; 10.5–17.5 kg). Scaling relationships suggest that the Rodrigues solitaire may not have been as large as Leguat's estimate (in 1708) of a body mass of 45 lb (20.4 kg).

Distribution

Extinct, known only from Mauritius, Rodrigues, and possibly Réunion islands in the Indian Ocean

Habitat

Woodlands; no journal account associates either species with shore or river banks

Behavior

Despite the attention the birds received as curiosities by early seventeenth century visitors, nothing was recorded of the dodo's habits. The habits of the Rodrigues solitaire were better documented by Leguat and another later, brief account. Rodrigues solitaires, at least, were territorial. They produced wing sounds in apparent courtship displays and made use of wing spurs in agonistic encounters.

Feeding ecology and diet

The dodo diet was described as fruit and that of the Rodrigues solitaire as seeds, fruit, and foliage. Gizzard stones have been found in association with skeletal remains of both species. A marked annual fat cycle, common for many Mascarene species, has been postulated for the dodo. Such a cycle had been reported by Legaut for the Rodrigues solitaire: fat from March to September and thin the remainder of the year.

Stanley Temple postulated a close mutualistic relationship between the dodo and the tambalacoque tree (Sideroxylon grandiflorum; also known as Calvaria major) in that germination of the tree's hard seeds was promoted (or assisted) by passage through the dodo's gut. However, evidence for this relationship is tenuous.

Reproductive biology

There is very little information of undisputed acceptance. These species probably laid clutches of a single egg in nests on the ground. Young were probably altricial (hatched helpless and requiring considerable care), but no information exists to describe either their appearance or development. Leguat described Rodrigues solitaire adults bringing young together to a vacant territory as an arranged "marriage," but this behavior may represent formation of creches of young.

Conservation status

Extinct; dodo by 1670, Rodrigues solitaire by 1770, Réunion solitaire by 1750. Primary cause of extinction attributed to predation on eggs and young by pigs (Sus scrofa), rats (Rattus rattus and R. norvegicus), and, on Mauritius, monkeys (Macaca fascicularis). Cats (Felis catus) may have also have played a role. Introduced herbivores—cattle (Bos taurus), goats (Capra spp.), and, on Mauritius, deer (Cervus timorensis—likely altered native habitat, but this impact on dodo and solitaire populations was probably not as severe as that caused by predation by pigs, rats, and monkeys. Early extinctions of other native species on the Mascarene Islands are also attributed to introductions of exotic species.

Significance to humans

Dodos and solitaires were killed for food and to restock supplies of ships visiting the islands. While still extant, these species were presented to Europe as curiosities of exotic islands. The very short time between their European discovery and their extinction has enhanced their cultural significance as symbols of extinction.

Species accounts

Resources

Cheke, A.S. "An Ecological History of the Mascarene Islands, with Particular Reference to Extinctions and Introductions of Land Vertebrates." In Studies of Mascarene Island Birds, edited by A.W. Diamond. Cambridge: Cambridge University Press, 1987.

Hachisuka, M. The Dodo and Kindred Birds, or the Extinct Birds of the Mascarene Islands. London: Witherby, 1953.

Quammen, D. The Song of the Dodo: Island Biogeography in an Age of Extinctions. New York: Scribner, 1996.

Strickland, H.E., and A.G. Melville. The Dodo and Its Kindred. London: Reeve, Benham and Reeve, 1848.

Brom, T.G., and T.G. Prins. "Microscopic Investigation of Feather Remains from the Head of the Oxford Dodo, Raphus cucullatus." Journal of Zoology (London) 218 (1989): 233–246.

Kitchener, A.C. "On the External Appearance of the Dodo, Raphus cucullatus (L., 1758)." Archives of Natural History 20 (1993): 279–301.

Livezey, B.C. "An Ecomorphological Review of the Dodo (Raphus cucullatus) and Solitaire (Pezophaps solitaria), Flightless Columbiformes of the Mascarene Islands." Journal of Zoology (London) 230 (1993): 247–292.

Mourer-Chauviré, C., R. Bour, and S. Ribes. "Was the Solitaire of Réunion an Ibis?" Nature 373 (1995): 568.

Owadally, A.W. "The Dodo and the Tambalacoque Tree." Science 203 (1979): 1363–1364.

Temple, S.A. "Plant-Animal Mutualism: Coevolution with Dodo Leads to Near Extinction of Plant." Science 197 (1977): 885–886.

[Article by: Peter E. Lowther, PhD]

The noun has one meaning:

Meaning #1: extinct dodos and solitaires
  Synonym: family Raphidae