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Raphinae

The Raphinae are a subfamily of birds within the family Columbidae (pigeons and doves), encompassing a diverse clade of primarily Old World species that includes fruit-doves, imperial pigeons, crowned pigeons, and the extinct flightless didines such as the dodo (Raphus cucullatus) and Rodrigues solitaire (Pezophaps solitaria).^[1]^[2] This subfamily is characterized by its monophyletic grouping based on molecular phylogenetic evidence, with a biogeographic focus on Indomalayan and Australasian regions, reflecting evolutionary adaptations to island and forest habitats.^[3]^[4] Phylogenetically, Raphinae is one of three major subfamilies in Columbidae; together with Peristerinae, it is sister to Columbinae, with the Nicobar pigeon (Caloenas nicobarica) serving as the closest living relative to the didine lineage.^[2] The subfamily's taxonomy has evolved through genetic studies, prioritizing the name Raphinae over older terms like Treroninae, and includes tribes such as Raphini (encompassing crowned pigeons Goura and the extinct didines), Ptilinopodini (fruit-doves Ptilinopus and allies), Phabini (ground-doves like Gallicolumba), and Chalcophabini (emerald doves Chalcophaps).^[1]^[4] These birds exhibit varied morphologies, from arboreal fruit-eaters to terrestrial forms, with multiple instances of flight reduction in island isolates.^[3] Notable for both extant diversity (over 100 species across genera like Ducula and Gymnophaps) and iconic extinctions, Raphinae highlights human impacts on island avifauna; the dodo, once endemic to Mauritius, and the solitaire from Rodrigues became extinct in the 17th and 18th centuries due to habitat loss and introduced predators.^[5] Recent analyses, including ancient DNA from specimens like the spotted green pigeon (Caloenas maculata), underscore the subfamily's evolutionary history of island hopping from Southeast Asia.^[5] Conservation efforts now focus on threatened species within the group, emphasizing their role in seed dispersal and forest ecosystems.^[4]

Taxonomy and classification

Etymology and naming

The subfamily name Raphinae is derived from the genus Raphus, established by Mathurin Jacques Brisson in 1760 for the dodo (Raphus cucullatus), with the suffix -inae indicating a taxonomic subfamily in New Latin nomenclature. The genus Raphus itself traces back to Johann Friedrich Wilhelm von Moehring's 1758 work Avium Genera, where it was applied to the dodo, likely drawing from the Greek term raphos (a name used by ancient author Galenus for the great bustard, Otis tarda), though the precise connection remains debated and may involve a misreading of related terms like otis (bustard). Brisson adopted and formalized Raphus in his Ornithologie, placing the dodo near bustards due to perceived morphological similarities, such as robust build and reduced wings. This naming reflected early attempts to classify the enigmatic bird within known avian groups, predating molecular insights into its pigeon affinities.^[6] Earlier historical terms for the group included "Didines," originating from Carl Linnaeus's 1766 renaming of the dodo as Didus ineptus in the 12th edition of Systema Naturae, where Didus (a variant of Dido, possibly evoking the mythological queen or simply a neologism for the "inept" or foolish bird) replaced Brisson's Raphus under principles of binomial nomenclature. Linnaeus's choice emphasized the dodo's perceived stupidity, echoing the common name "dodo," which derives from the Portuguese doudo (meaning "foolish" or "simple"), a term likely applied by 16th-century Portuguese sailors to describe the bird's tame, fearless behavior toward humans. For the Rodrigues solitaire (Pezophaps solitaria), the vernacular "solitaire" stems from François Leguat's 1708 travelogue Voyage et Mémoires, which described the bird as a solitary, pedestrian pigeon (solitaire implying its lone wandering habits on the island), a name later formalized in scientific literature. These terms collectively highlighted the birds' isolated island existence and unusual traits before their extinction. The classification of Raphinae evolved through 19th-century ornithology, beginning with George Robert Gray's 1840 establishment of the subfamily Didinae (based on Linnaeus's Didus) within Columbidae in A List of the Genera of Birds, marking an initial recognition of close ties to pigeons rather than rails or other groups. Hugh Edwin Strickland's seminal 1848 monograph The Dodo and Its Kindred, co-authored with Alexander Gordon Melville, further solidified this by analyzing osteological evidence from dodo and solitaire specimens, arguing for their placement as a distinct subfamily of pigeons and rejecting earlier misconceptions of affinities with ratites or galliforms. By the mid-19th century, the group was often treated as a separate family, with names like Dididae (Swainson, 1835) or Raphidae proposed, but subsequent revisions—such as Verheyen's 1957 designation of Raphinae as a subfamily—subsumed it firmly within Columbidae based on anatomical and later genetic data, reflecting a consensus on their evolutionary position as flightless columbids. Recent molecular studies have expanded Raphinae to include a broader monophyletic clade of Old World pigeons.^[6]

Phylogenetic relationships

The Raphinae is recognized as a monophyletic subfamily within the family Columbidae, encompassing a diverse clade of primarily Old World species including fruit-doves, imperial pigeons, crowned pigeons, and the extinct flightless didines such as the dodo (Raphus) and Rodrigues solitaire (Pezophaps), based on molecular phylogenetic analyses of mitochondrial and nuclear DNA sequences that embed these taxa among pigeons and doves.^[7] Recent nomenclature revisions confirm this placement, drawing on seminal DNA studies that resolve Raphinae as derived from volant columbid ancestors rather than a separate family.^[7] Molecular clock estimates indicate that the Raphinae clade diverged from its sister subfamilies (Peristerinae and Columbinae), with the Nicobar pigeon (Caloenas nicobarica) as the closest living relative outside the subfamily, during the Oligocene, approximately 18–26 million years ago, positioning Raphinae as a major radiation among columbids focused on Indomalayan and Australasian regions.^[8]^[5] This divergence reflects an early radiation, with flightlessness evolving independently in the didine lineages (Raphus and Pezophaps) around 13–18 million years ago.^[8]^[7] Fossil evidence supporting the evolutionary history of Raphinae is sparse, with limited remains from island deposits suggesting origins via dispersal from Southeast Asia.^[7] Cladistic analyses, integrating morphological and molecular data, consistently support the monophyly of Raphinae, with the didines forming a derived subgroup characterized by shared synapomorphies including reduced wings and robust skeletal adaptations for terrestrial life, distinct from other columbid clades.^[7]^[5]

Genera and species

The Raphinae subfamily comprises approximately 33 genera and over 100 species, organized into four main tribes based on phylogenetic analyses: Raphini (including crowned pigeons Goura, tooth-billed pigeon Didunculus, and the extinct didines Raphus and Pezophaps), Ptilinopodini (fruit-doves Ptilinopus and allies, imperial pigeons Ducula), Phabini (ground-doves like Gallicolumba), and Chalcophabini (emerald doves Chalcophaps).^[1]^[6] This classification reflects a monophyletic grouping of primarily arboreal and terrestrial forms adapted to island and forest habitats in the Old World tropics. Within Raphini, the extinct didines include two recognized genera, each with a single species endemic to the Mascarene Islands. The genus Raphus includes Raphus cucullatus (Linnaeus, 1758), the dodo, native to Mauritius and last reliably sighted in 1662. The genus Pezophaps includes Pezophaps solitaria (Gmelin, 1789), the Rodrigues solitaire, endemic to Rodrigues Island and last reported around 1761, with extinction confirmed by the late 18th century. No subspecies are recognized for either. Historical synonymy includes Didus ineptus (Linnaeus, 1766) and Didus solitarius (Gmelin, 1789) for R. cucullatus and P. solitaria, respectively, with Didus as an objective synonym of Raphus. Other junior synonyms for the dodo include Struthio cucullatus (Linnaeus, 1758) and Raphus raphus (Brisson, 1760).^[6]

Tribe	Example Genera	Notable Species/Notes	Status (Didines Only)
Raphini	Goura, Didunculus, Raphus, Pezophaps	Crowned pigeons (extant); dodo and solitaire (extinct, Mascarene Islands)	IUCN Extinct (didines)
Ptilinopodini	Ptilinopus, Ducula, Gymnophaps	Fruit-doves (~50 spp.), imperial pigeons (36 spp.); mostly extant	Varies; some threatened
Phabini	Gallicolumba, Geophaps	Ground-doves; extant diversity	Varies
Chalcophabini	Chalcophaps, Turtur	Emerald doves, wood-doves; extant	Varies

Modern classifications by the International Ornithological Congress (IOC World Bird List, as of version 14.1, 2024) and Handbook of the Birds of the World place Raphinae within Columbidae, confirming its broad phylogenetic scope with the didines as an iconic extinct subgroup.^[9]^[6]

Physical description

Morphology and size

Members of the Raphinae subfamily exhibit considerable morphological diversity, ranging from small, colorful arboreal fruit-doves to large, crested ground-dwellers and the extinct flightless didines. Most species are volant, with body lengths from about 15 cm in small fruit-doves like Ptilinopus superbus (weighing 40–60 g) to 75 cm in crowned pigeons (Goura spp., up to 2–4 kg), and imperial pigeons (Ducula spp.) reaching 50–70 cm and 300–800 g. Plumage varies widely: fruit-doves often feature vibrant greens, reds, and yellows with rounded wings and short tails suited for forest canopy foraging, while imperial and crowned pigeons show more subdued greys and blues, with the latter displaying prominent lacy crests.^[10] The extinct didines, such as the dodo (Raphus cucullatus) and Rodrigues solitaire (Pezophaps solitaria), represent extreme adaptations to island life, with robust, flightless morphologies and bodies significantly larger than most columbids. The dodo possessed a plump, barrel-shaped torso supported by stout yellow legs, standing approximately 90 cm tall in males and weighing an estimated 10.6–14.3 kg in the wild based on subfossil reconstructions and volumetric modeling of articulated skeletons.^[11] Its plumage was predominantly greyish, with lighter primary feathers and a distinctive tuft of curly, pale feathers forming the tail, while the head featured a large, naked face with a fleshy wattled patch around the bill. The beak was notably large and hooked, reaching up to 23 cm in length, suited for foraging on fruits and seeds, and the wings were vestigial, measuring only about 10 cm long with minimal feathering.^[12] The Rodrigues solitaire displayed a slimmer, more upright build compared to the dodo, with males reaching heights of about 90 cm and body masses around 17–28 kg, while females were smaller at roughly 70 cm and 17 kg, reflecting pronounced sexual dimorphism. Its plumage was greyish-white overall, with brownish tones on the dorsal surface and a paler, sometimes white chest in females; males showed more vibrant coloration. The beak was shorter and stouter than the dodo's, approximately 5 cm long and hooked, while the wings were similarly reduced but featured a prominent carpal knob—resembling a musket ball in size—on the wrist, larger in males and used in territorial displays.^[13] Legs were longer and more robust than in typical pigeons, with feathered tarsi and scaled toes adapted for terrestrial locomotion.^[12] Subfossil evidence reveals a consistently robust build in the didines, with both genera showing greater overall size than flying columbids, such as the Nicobar pigeon, and adaptations like reduced wings emphasizing their terrestrial lifestyle.^[12] Sexual dimorphism was particularly evident in the solitaire, where males exceeded females in height and mass by up to 60%, and in the dodo, where males were similarly larger, influencing reconstructions of population dynamics and behavior.

Anatomical adaptations

The Raphinae display varied anatomical features reflecting their diverse habitats, from arboreal to terrestrial, with volant species retaining typical columbid traits like strong flight-capable pectoral girdles and zygodactyl feet for perching. In the extinct flightless didines (Raphus and Pezophaps), pronounced skeletal modifications consistent with loss of flight and adaptation to predator-free island environments are evident. These birds displayed a reduced sternal keel, a feature typical of flightless avians, which minimized the attachment area for pectoral flight muscles while retaining a vestigial structure unlike the complete absence in ratites.^[14] The dodo's sternum was particularly abbreviated and shallow, with a more vestigial keel compared to the solitaire's slightly more developed but still diminished form, reflecting parallel evolution of terrestriality from flying columbiform ancestors.^[15] Occasional fusion of the coracoid and scapula observed in some dodo specimens may have strengthened the shoulder girdle for weight-bearing, a trait not consistently present and distinct from volant pigeons.^[15] Thoracic vertebrae showed partial fusion into a notarium comprising three elements in the dodo, providing axial stability for a heavy, ground-dwelling lifestyle without the need for aerial maneuvering.^[16] Hindlimb enhancements further underscored cursorial adaptations in the didines, with robust pelvic girdles and elongated lower leg bones supporting efficient terrestrial locomotion. In the solitaire, the tibiotarsus was notably longer than the humerus, emphasizing leg dominance over vestigial wings, while the dodo featured extended femora and robust tarsometatarsi with thick shafts for stability on uneven terrain.^[17] These modifications paralleled those in flightless rails, such as increased hindlimb robusticity, but the Raphinae retained columbid-specific traits like a pronounced cnemial crest on the tibiotarsus for enhanced kicking force during foraging or defense.^[18] Wing elements were severely reduced, with the humerus exceeding the ulna by about 25% in the dodo—opposite to the proportions in flying pigeons—indicating minimal musculature and paedomorphic underdevelopment of the pectoral girdle.^[16] Physiological traits complemented these skeletal shifts, particularly in digestive adaptations for a frugivorous diet on isolated islands. Subfossil evidence reveals an enlarged gizzard in the dodo, inferred from large gastroliths used to grind tough seeds and fruits, a specialization beyond that of smaller columbids.^[19] The retention of a crop, a hallmark of pigeon-like birds, allowed initial softening of ingested material before gizzard processing, facilitating survival on nutrient-dense but fibrous island vegetation.^[17] Endocranial studies indicate the dodo's brain volume was proportional to its body size, akin to modern pigeons, suggesting cognitive capabilities adequate for complex foraging in varied habitats rather than exceptional intelligence.^[20] Bone histology further shows rapid juvenile growth followed by prolonged skeletal maturation, with multiple lines of arrested growth in hindlimb bones, indicative of low-predation longevity and energy allocation toward maintenance over rapid reproduction.^[18]

Distribution and ecology

Historical range

The Raphinae subfamily has a broad historical range centered in the Indomalayan and Australasian regions, with species distributed from Southeast Asia through the Malay Archipelago, New Guinea, and into the Pacific islands as far as the Solomon Islands.^[21] This distribution reflects evolutionary island hopping from continental Asia, as evidenced by molecular and fossil data, including ancient DNA from the spotted green pigeon (Caloenas maculata), indicating origins in Southeast Asian forests before dispersal to oceanic islands.^[5] Within this range, the extinct tribe Raphini (didines) was endemic to the Mascarene Islands, a volcanic archipelago in the southwestern Indian Ocean approximately 2,000 kilometers east of Madagascar. These islands emerged from hotspot activity, with Mauritius forming around 8–10 million years ago, followed by Réunion about 2.8 million years ago and Rodrigues roughly 1.5 million years ago. Isolated from continental landmasses, they fostered high endemism. The dodo (Raphus cucullatus) inhabited diverse lowland forests, wetlands, and coastal regions of Mauritius, while the Rodrigues solitaire (Pezophaps solitaria) was confined to the central plateau and wooded areas of Rodrigues. Claims of a third raphine on Réunion stem from ambiguous 17th-century descriptions, likely referring to the Réunion ibis (Threskiornis solitarius) rather than a pigeon; no subfossil evidence supports a raphine there.^[22] Subfossil records from Mauritius's Mare aux Songes marsh (dated to around 4,200 years before present) and Rodrigues's Plaine Corail caves confirm this restricted distribution for didines, with no pre-human presence beyond the Mascarenes.^[19] Pre-human population estimates for the dodo on Mauritius suggest tens of thousands, ranging from 80,000 individuals during interglacial minima to 128,000 at glacial maxima, based on ecological modeling of habitat and climate fluctuations. For the Rodrigues solitaire, estimates range from about 7,000 in interglacial periods to over 50,000 during glacial maxima, reflecting the island's smaller carrying capacity and territorial behavior.^[23]

Habitat and environmental preferences

Raphinae species are primarily adapted to tropical and subtropical island and forest ecosystems across their Indomalayan-Australasian range, favoring closed-canopy rainforests, mangroves, and montane forests where they exploit fruit resources as key seed dispersers. Many, such as fruit-doves (Ptilinopus) and imperial pigeons (Ducula), are arboreal and occur in lowland to highland elevations up to 3,000 m, with some like crowned pigeons (Goura) in New Guinea's lowland swamps. Island isolation has led to flight reduction in several lineages, including the didines.^[3]^[1] The extinct didines exemplify extreme adaptations to Mascarene isolation. The dodo primarily inhabited coastal lowlands of Mauritius, favoring evergreen forests and coastal woodlands with wet canopy and semi-dry ecotones, supported by a tropical climate with mean annual rainfall below 1,300 mm and trade wind-influenced seasons. It relied on native palms like the tambalacoque (Sideroxylon grandiflorum) and fruit trees such as Eugenia elliptica.^[24] The Rodrigues solitaire occupied drier scrublands, savannas, and sparse dry forests on Rodrigues, adapted to arid conditions with lower precipitation and prolonged dry seasons, feeding on fallen fruits and hard seeds from endemic plants.^[25] Both served as ground-dwelling herbivores and seed dispersers in predator-free environments lacking large vertebrates.^[26] Prolonged isolation shaped Raphinae preferences, including flightlessness and reduced anti-predator behaviors in island forms due to absent mammalian predators, leading to naivety toward introduced threats.^[27]^[12]

Behavior and lifestyle

Diet and foraging

Members of the Raphinae subfamily are primarily frugivorous and granivorous, with diets dominated by fruits, seeds, and nuts, though many incorporate invertebrates such as insects and snails.^[28]^[29] Extant species like fruit-doves (Ptilinopus spp.) and imperial pigeons (Ducula spp.) forage arboreally in forest canopies, swallowing whole fruits such as figs and berries, and play key roles as seed dispersers by passing intact seeds.^[30] Ground-dwelling genera, such as ground-doves (Gallicolumba spp.) and emerald doves (Chalcophaps spp.), forage on the forest floor for fallen fruits, seeds, and small invertebrates.^[31]^[32] The extinct flightless didines, including the dodo (Raphus cucullatus) and the Rodrigues solitaire (Pezophaps solitaria), were primarily frugivorous, relying on a diet dominated by fruits, seeds, and nuts available in their island habitats.^[17] Historical accounts from Dutch sailors in the early 17th century describe the dodo consuming raw fruits, with stomach contents noted for their palatability when prepared as food.^[33] Subfossil evidence and contemporary observations suggest occasional inclusion of tubers, marine invertebrates, and small vertebrates, though plant material formed the core of their intake.^[12] For the Rodrigues solitaire, limited historical records indicate a similar herbivorous diet consisting of hard seeds, fallen fruits, and leaves, potentially including dates from native palms.^[26] Like the dodo, the solitaire's robust beak was adapted for processing tough plant matter, with no strong evidence supporting a significantly more carnivorous habit despite its bone-like structure.^[17] Foraging in the extinct didines was ground-based, utilizing their strong legs and beaks to probe forest floor litter and soil for food items.^[17] They employed gastroliths—smooth stones retained in the gizzard—to aid mechanical digestion of hard seeds and nuts, a trait evidenced by stones found in dodo remains and inferred for the solitaire through shared anatomy.^[33] Daily patterns were likely diurnal, with individuals foraging solitarily or in small groups, reflecting the behavior of their columbiform relatives and the lack of nocturnal adaptations in subfossil skulls.^[17] As large-bodied frugivores, Raphinae played a key trophic role in island and forest ecosystems, acting as both seed predators and dispersers through their consumption and passage of intact seeds via the digestive tract.^[34] Their extinction disrupted these interactions, contributing to the decline of dependent plant species, though the precise balance between predation and dispersal remains uncertain due to limited direct evidence.^[34]

Reproduction and life cycle

Raphinae species typically lay a single egg (occasionally two in some fruit-doves), with biparental care including incubation and feeding via crop milk.^[30] Extant members construct flimsy platform nests of twigs in trees or shrubs, often in forest canopies, with incubation periods of 18–30 days depending on species size.^[35] Breeding is often seasonal, tied to fruit availability or rainy periods in tropical regions, and chicks are precocial, leaving the nest soon after hatching but remaining dependent on parents.^[36] The extinct didines, including the dodo (Raphus cucullatus) and Rodrigues solitaire (Pezophaps solitaria), constructed ground nests concealed in leaf litter, a habit inferred from their flightless morphology and the ecology of their island habitats.^[37] These nests accommodated a single large egg per breeding attempt, with egg mass comparable to that expected for flight-capable columbids of similar body size.^[12] Incubation lasted approximately 30 days, estimated from the closest living relative, the Nicobar pigeon (Caloenas nicobarica), which requires 28–30 days for a clutch of similar relative size.^[38] Breeding occurred seasonally in the austral winter, with ovulation in August for the dodo, aligning egg hatching in September to allow rapid chick growth ahead of the cyclone season (November–March); this timing likely tied to peak fruit availability as frugivores.^[37] Chicks were downy at hatching and exhibited precocial traits, enabling quick mobility, though they received crop milk from parents as in other columbids.^[37] Parental care was biparental, with both sexes sharing incubation and chick-rearing duties, while males in the solitaire defended territories aggressively using specialized wing spurs.^[12]^[39] The life cycle of the didines featured slow maturation, with skeletal development continuing for 2–5 years post-hatching in the dodo, reaching breeding age around 2–3 years.^[37] Lifespan reached up to 20 years, inferred from bone growth lines indicating multiple annual cycles and comparisons to large columbids.^[37] This extended ontogeny, combined with a single egg per season, resulted in low reproductive rates—typically one offspring annually—heightening vulnerability to environmental perturbations and human impacts.^[12]

Extinction and conservation history

Timeline of extinctions

The extinctions of the Raphinae species unfolded rapidly in the 17th and 18th centuries following European contact with the Mascarene Islands, with sailor and explorer accounts providing the primary historical records. The dodo (Raphus cucullatus) on Mauritius was first documented by Dutch explorers in 1598, marking the onset of human impact on the population.^[19] The species declined precipitously thereafter, with the last confirmed sighting occurring in 1662 by the shipwrecked Dutch sailor Volkert Evertsz, who reported encountering a single live individual on an offshore islet.^[19]^[40] The Rodrigues solitaire (Pezophaps solitaria) persisted longer on the neighboring island of Rodrigues, with reports indicating it remained relatively common as late as 1733.^[25] By 1761, however, a French scientific expedition led by astronomer Abbé Pingré to observe the transit of Venus failed to locate any live birds despite targeted searches, signaling the species' extinction shortly thereafter.^[25]^[41] Subfossil remains, including bones encrusted in stalagmites, were first collected from caves in 1786 and continued to be unearthed and analyzed into the 1790s, confirming the bird's prior existence but underscoring its complete disappearance from the wild.^[25]

Causes of decline

The extinction of flightless Raphinae species, including the dodo (Raphus cucullatus) on Mauritius and the Rodrigues solitaire (Pezophaps solitaria) on Rodrigues, was driven primarily by habitat destruction and predation resulting from introduced invasive species. Feral pigs (Sus scrofa), rats (Rattus spp.), goats (Capra hircus), and cats (Felis catus) were transported to the Mascarene Islands by European sailors and settlers starting in the late 16th century, where they devastated native ecosystems by consuming eggs, chicks, and seedlings of endemic plants that formed the birds' food base.^[24] These invasives also trampled and browsed understory vegetation, leading to widespread degradation of the closed-canopy forests that Raphinae species relied on for shelter and foraging.^[18] Direct hunting by humans further exacerbated the decline, as flightless and tame due to the absence of natural predators, the birds were easily captured for food by shipwrecked sailors and early colonists, particularly targeting solitaires during the tortoise trade on Rodrigues in the 1730s–1750s.^[6] Secondary factors compounded these pressures, including potential disease transmission from introduced mammals and competition for limited resources in the increasingly fragmented habitats. Island isolation had resulted in low genetic diversity among Raphinae populations, reducing their resilience to rapid environmental changes and novel threats.^[42] While overhunting alone was not the dominant cause—given small human populations on the islands (never exceeding a few hundred during initial contacts)—the combined effects of invasives and opportunistic harvesting proved catastrophic within decades of human arrival.^[24] Human activities from the 1500s onward accelerated the loss, as Portuguese, Dutch, and French explorers used the Mascarenes as stopover points, inadvertently or deliberately introducing invasives and clearing land for provisioning stations and later plantations. Colonial settlement intensified deforestation for timber, agriculture, and grazing, with no effective conservation measures implemented until the 19th century, long after the flightless didines had vanished.^[18] Modern studies, including analyses of subfossil deposits and historical records, reveal that invasive species caused extensive habitat degradation across the Mascarenes by the late 18th century, with forest cover in Mauritius reduced to approximately 82.5% of original by 1773 and over 90% lost overall since human settlement by the mid-20th century.^[43]^[44] These insights underscore how interactions between human-mediated introductions and ecological naivety led to the rapid collapse of didine populations, serving as a cautionary example for island biodiversity conservation.^[42]

Conservation of extant species

While the flightless didines are extinct, many extant Raphinae species face threats from habitat loss, hunting, and invasive species, particularly in island ecosystems of the Indo-Pacific. As of 2025, the International Union for Conservation of Nature (IUCN) lists several as vulnerable or near-threatened, including the Nicobar pigeon (Caloenas nicobarica), the closest living relative to the didines, due to logging and poaching.^[45] Conservation efforts include the IUCN Species Survival Commission's Pigeon and Dove Specialist Group, established to coordinate global actions for Columbiformes, focusing on habitat protection, anti-poaching measures, and reforestation in key areas like the Philippines and Indonesia.^[46] Protected areas, such as national parks in Papua New Guinea for crowned pigeons (Goura spp.), support seed dispersal roles vital to forest health. Recent initiatives, including genetic studies and de-extinction projects by organizations like Colossal Biosciences, aim to revive the dodo using Nicobar pigeon genomes, while enhancing conservation for living relatives.^[47]

Human interactions and legacy

Historical discovery

The first documented encounters with Raphinae occurred in 1598, when Dutch sailors under Admiral Wybrand van Warwijck landed on Mauritius and described the dodo (Raphus cucullatus), a large flightless bird endemic to the island. These early accounts, recorded in ship journals, portrayed the dodo as a tame, bulky creature easily approachable by humans, with grey plumage, a large hooked beak, and rudimentary wings. The origin of the name "dodo" is uncertain, but is commonly attributed to the Portuguese word "doudo," meaning "fool" or "simpleton," likely referring to the bird's tame and approachable behavior.^[48]^[40]^[49] Preserved dodo specimens soon reached Europe, with at least one arriving alive in the Netherlands around 1600. Botanist Carolus Clusius examined such a specimen in 1601, dissecting its foot and providing one of the earliest scientific descriptions, which emphasized its unique anatomy including a robust leg structure and gizzard stones. His detailed account and illustration appeared in the 1605 publication Exoticorum libri decem, influencing subsequent European depictions and establishing the dodo as a curiosity in natural history cabinets.^[50] The Rodrigues solitaire (Pezophaps solitaria), a close relative from the nearby island of Rodrigues, was first noted in 1691 by French explorer François Leguat during his two-year stay on the island as part of a Huguenot refugee group. Leguat's memoir, published in 1708, offered the most comprehensive early description, depicting the solitaire as a greyish bird about the size of a swan, with a short tail, knobbed wings used in mating displays, and a diet including fruits and tubers; he included the only eyewitness illustration of the living bird. Initial European interpretations often conflated the solitaire with the dodo due to shared flightless traits and Mascarene origins, leading to taxonomic confusion in early literature.^[51]^[52] Among early collections, the Oxford dodo specimen—acquired by the Tradescant family by 1656 and later donated to the Ashmolean Museum—stands out as a key artifact; originally a full skin and skeleton, only the desiccated head and foot survive today after the body was reportedly discarded in the 1750s to make room for newer exhibits.^[40] The scarcity of complete remains spurred 19th-century subfossil excavations, notably by George Clark, a Mauritian schoolmaster who, starting in 1865, unearthed hundreds of dodo bones from the Mare aux Songes marsh using local laborers and rudimentary tools like banana-trunk rafts to navigate the muddy site. These discoveries provided the first substantial skeletal material for study.^[53] By the mid-19th century, anatomists including Richard Owen and Alfred Newton analyzed these subfossils, sparking debates on Raphinae classification. Owen's 1866 memoir described dodo postcranial bones, while Newton, in collaboration with others, argued for close affinities to pigeons (Columbidae) based on shared features like the structure of the palate, quadrate bone, and hindlimb proportions, positioning Raphinae as a derived subfamily of flightless columbids rather than related to rails or other groups. This recognition, solidified in works like Newton's 1879 contributions, marked a pivotal shift in understanding their evolutionary position.^[54]^[6]

Cultural and scientific significance

The dodo (Raphus cucullatus), the most emblematic member of the Raphinae subfamily, has evolved into a powerful cultural symbol of extinction and human environmental impact. Its portrayal in Lewis Carroll's Alice's Adventures in Wonderland (1865), where the bird leads a futile "caucus race" among fantastical creatures, introduced it to global audiences and reinforced its image as a hapless, doomed figure in popular imagination.^[55] This literary role has permeated broader culture, inspiring phrases like "as dead as a dodo" to denote utter obsolescence and appearing in art, films, and conservation campaigns as a cautionary emblem of biodiversity loss.^[56] The Rodrigues solitaire (Pezophaps solitaria), though less ubiquitous in popular media, features in historical travel narratives and scientific literature, underscoring the shared fate of Raphinae species as icons of island endemism and rapid extinction.^[57] These birds collectively represent the fragility of isolated ecosystems in cultural discourse, often invoked in discussions of anthropogenic change. Scientifically, Raphinae taxa have profoundly influenced biogeography and evolutionary biology, serving as quintessential case studies for the MacArthur-Wilson equilibrium theory of island biogeography, which models species diversity based on immigration and extinction rates on isolated landmasses.^[58] David Quammen's The Song of the Dodo (1996) exemplifies this legacy, using the dodo's extinction to illustrate how human activities disrupt island equilibrium and accelerate global biodiversity decline. Ancient DNA analyses in the early 2000s further solidified their phylogenetic placement within Columbidae, with mitochondrial sequencing from dodo and solitaire remains confirming close ties to pigeons like the Nicobar pigeon, resolving long-standing taxonomic debates. The extinction of Raphinae has informed modern conservation strategies, particularly in Mauritius, where restoration projects by organizations like the Mauritian Wildlife Foundation aim to rehabilitate native forests and remove invasives, drawing direct inspiration from the dodo's historical habitat loss to prevent similar fates for surviving endemics. Recent phylogenetic research, such as a 2024 study reevaluating Raphinae systematics using molecular and morphological data, continues to refine understandings of their evolutionary history and columbid affinities.^[6] Discussions around de-extinction technologies, including CRISPR-based gene editing of pigeon genomes to recreate dodo traits, continue, with Colossal Biosciences reporting key advances in September 2025, such as culturing pigeon primordial germ cells and preparing surrogates, though full revival remains challenging and is linked to broader ecosystem goals.^[59]^[60]

References

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[3]
Add subfamilies to Columbidae
... Raphinae (all remaining Old World genera except Streptopelia, Nesoenas, Macropygia, Turacoena, Reinwardtoena; this group has a strongly Indomalayan ...<|control11|><|separator|>
[4]
A molecular phylogenetic analysis of the genera of fruit doves and ...
Aug 15, 2019 · In particular our goal is to identify which of these genera should be included within Raphinae (the name which has taxonomic priority over ...
[5]
The mysterious Spotted Green Pigeon and its relation to the Dodo ...
Jul 16, 2014 · ... Raphinae, are members of a clade of morphologically very diverse pigeons. ... Columbidae / classification*; Columbidae / genetics*; Extinction ...
[6]
systematics and nomenclature of the Dodo and the Solitaire (Aves
Aug 16, 2024 · ... Raphus, a name given to this genus by Moehringius'). Note that Brisson (1760a, b) used both Raphus and Raphi for the generic name. It is ...<|control11|><|separator|>
[7]
https://doi.org/10.1093/zoolinnean/zlae086
[8]
Complete mitochondrial genomes of living and extinct pigeons ...
Oct 26, 2016 · To evaluate the robustness of our molecular clock approach, we performed an additional analysis in which we estimated divergence times at the ...Missing: Raphinae | Show results with:Raphinae
[9]
https://www.worldbirdnames.org/new/
[10]
https://birdsoftheworld.org/bow/families/4/cur/introduction
[11]
An ecomorphological review of the dodo (Raphus cucullatus) and ...
Aug 7, 2025 · Body mass and size measurements were estimated to be 28 kg (90 cm) and 17 kg (70 cm) for male and female, respectively (Livezey 1993). ...
[12]
https://www.researchgate.net/publication/229522550_An_ecomorphological_review_of_the_dodo_Raphus_cucullatus_and_solitaire_Pezophaps_solitaria_flightless_Columbiformes_of_the_Mascarene_Islands
[13]
Embryonic Development of the Avian Sternum and Its Morphological ...
Sep 29, 2021 · Despite the kakapo and the extinct, dodo, having also lost their flying ability, a sternal keel is still present, although it is greatly reduced ...Missing: vertebrae | Show results with:vertebrae
[14]
The Morphology of the Thirioux dodos - ResearchGate
Aug 10, 2025 · Here we describe the skeletal anatomy of two exceptional dodo specimens, collected around 1904 by amateur naturalist Louis Etienne Thirioux.
[15]
Raphidae | extinct bird family - Britannica
Sep 18, 2025 · It had blue-gray plumage, a big head, a 23-cm (9-inch) blackish bill with reddish sheath forming the hooked tip, small useless wings, stout ...Missing: GR | Show results with:GR
[16]
The Morphology of the Thirioux dodos - Academia.edu
Here we describe the skeletal anatomy of two exceptional dodo specimens, collected around 1904 by amateur naturalist Louis Etienne Thirioux in the caves and ...
[17]
An ecomorphological review of the dodo (Raphus cucullatus) and ...
The description of 'gigantic immaturity' in R. cucullatus by Strickland & Melville (1848) probably represents the first recognition of paedomorphosis in any ...
[18]
Bone histology sheds new light on the ecology of the dodo (Raphus ...
Aug 24, 2017 · Recent body mass estimates range from 9.5 kg to 14.3 kg; but almost no other information exists. Our research is therefore highly significant in ...
[19]
The dodo bird: The real facts about this icon of extinction
It had a large gizzard stone to help with digestion, which suggests it ate a diet of fallen fruits and seeds. CT scans of its braincase have revealed it had a ...Missing: Raphus | Show results with:Raphus
[20]
The first endocast of the extinct dodo (Raphus cucullatus) and an ...
Feb 23, 2016 · Enlarged olfactory bulbs are a shared characteristic of the Raphinae and posteriorly angled semicircular canals are particular to the dodo ...
[21]
[PDF] A synopsis of the pre-human avifauna of the Mascarene Islands
Dec 10, 2013 · All are volcanic in origin and have never been connected to each other or any other land mass.Missing: Raphinae | Show results with:Raphinae
[22]
https://verlag.nhm-wien.ac.at/buecher/2013_SAPE_Proceedings/15_Hume.pdf
[23]
A review of the dodo and its ecosystem: insights from a vertebrate ...
The bulk of the dodo subfossil material for pre-2005 studies on dodo anatomy were retrieved from an exceptionally rich vertebrate concentration Lagerstätte ...Missing: height | Show results with:height
[24]
Rodrigues Solitaire Pezophaps Solitaria Species Factsheet
The species was reportedly commonin 1733 (Gennes 1735) but supposedly declined rapidly after this time (Hume 2017). Reports suggest that Rodrigues harboured the ...Missing: pre- | Show results with:pre-
[25]
The Dodo and the Solitaire: A Natural History - ResearchGate
We used the average of these (13.75 kg) for the dodo's body mass. The Rodrigues solitaire's body mass was taken from Parish (2012) , who calculated masses of 13 ...<|control11|><|separator|>
[26]
The loss of anti-predator behaviour following isolation on islands - NIH
When isolated from predators, costly and no longer functional anti-predator behaviour should be selected against. Predator naiveté is often pronounced on ...
[27]
[PDF] The history of the Dodo Raphus cucullatus and the penguin of ...
The dodo's history is based on inadequate accounts, few illustrations, and limited fossil evidence. Early accounts are often misinterpretations, and few live ...
[28]
Extinctions on the island of the dodo are pushing plants towards ...
Mar 16, 2023 · While the dodo may have eaten the seeds, there's simply not enough evidence to know whether it acted as a seed disperser or a seed predator.Missing: Calvaria major
[29]
https://animalia.bio/common-emerald-dove?page=1
[30]
[PDF] Columbiformes - Harrison's Bird Foods
TABLE 44.7 Incubation Period and Fledging Age for Pigeons (in days). Common name. Incubation. Period. Fledging Age. Nicobar Pigeon. 28-30. 90. Blue-crowned ...
[31]
Possible resource‐defence polygyny in the extinct Rodrigues ...
Dec 23, 2015 · Possible resource-defence polygyny in the extinct Rodrigues Solitaire Pezophaps solitaria (Columbidae: Raphini). Ingvar Byrkjedal ...
[32]
The Oxford Dodo - Oxford University Museum of Natural History
Dodo birds were endemic to the island of Mauritius, in the Indian Ocean. It is thought that after the first explorers arrived on Mauritius in the late 1500s ...
[33]
[PDF] The History of the Dodo Bird and the Cause of Its Extinction
19 The Reunion. Solitaire has been extinct since the end of the seventeenth century, and the Rodriguez. Solitaire since the latter half of the eigh- teenth ...
[34]
Le musée du Dodo - DODO AND SOLITAIRES, MYTHS AND REALITY
A French astronomer, Abbé Gui Pingré (1763) who visited Rodrigues in 1761 to observe the transit of Venus, reported the bird to be near extinction. He had ...
[35]
The way of the dodo - ScienceDirect.com
Sep 23, 2024 · The real-life dodo (Raphus cucullatus) was a flightless bird of the pigeon family (Columbidae) endemic to Mauritius. This remote volcanic island ...
[36]
The Challenges and Future of Environmental Archaeology in Mauritius
Jan 29, 2024 · ... Mascarenes were loss of biodiversity, and the degradation or loss of habitat. These were driven by continued land clearance, invasive ...
[37]
'It's just a weird, weird bird': Why we got the dodo so absurdly wrong
Jul 15, 2025 · Successfully creating a dodo-like bird would allow scientists to see how the dodo interacts with other species in the Mauritian habitats, says ...Missing: thousands ancient
[38]
making and using a flightless monster in early modern natural history
Clusius's extensive dissection of the physical and textual evidence created a definitive dodo image that, along with the first travelogue description, was ...
[39]
The other Dodo: Extinct bird that used its wings as clubs - BBC
Dec 1, 2017 · Francois Leguat was marooned on the island of Rodrigues in 1601 where he encountered, described and drew the forgotten Rodrigues solitaire.
[40]
Remembering The Rodrigues Solitaire - Avibirds.com
Feb 3, 2021 · Extinction The Rodrigues solitaire is believed to have gone extinct by the 1760s. One theory posits that their extinction was linked to ...Missing: IUCN | Show results with:IUCN
[41]
How Owen 'stole' the Dodo: academic rivalry and disputed rights to a ...
George Clark, probable discoverer of the fossil site, sent consignments of bones initially to Richard Owen (British Museum), and subsequently to Alfred Newton, ...
[42]
[PDF] How Owen 'stole' the Dodo - Julian Hume
Mar 1, 2009 · Both Richard Owen and Alfred Newton shared the spoils of anatomically describing the two giant, flightless ground pigeons, but Owen succeeded in ...Missing: recognition | Show results with:recognition
[43]
Why do we still talk about the dodo? - University of Oxford
Sep 29, 2015 · ... dodo: an icon of extinction, and a powerful symbol of humanity's impact on the environment. It crosses disciplinary lines, encompassing ...
[44]
The Dodo is Dead, Long Live the Dodo! | National Geographic
Feb 10, 2011 · The last confirmed dodo sighting on its home island of Mauritius was made in 1662, but a 2003 estimate by David Roberts and Andrew Solow placed the extinction ...
[45]
Dodos and Solitaires (Raphidae) | Encyclopedia.com
Large turkey-like bird. Contemporary paintings of this species, based on live birds or traveler's descriptions, show grayish plumage, darker above and lighter ...Missing: classification | Show results with:classification
[46]
https://iucn.org/sites/default/files/2025-09/2024-2025-iucn-ssc-pigeon-and-dove-report_publication.pdf
[47]
Reviving the Dodo - Colossal Biosciences
Colossal plans to de-extinct the dodo using genomics, tissue culture, and interspecies surrogacy, partnering with MWF and the government of Mauritius.Missing: subfossil | Show results with:subfossil