The Réunion Swamphen, known to early French settlers as the oiseau bleu (blue bird) and sometimes called the Réunion gallinule, was a large, ground-dwelling rail that once lived in the mountainous heart of Réunion, a volcanic island in the Mascarene group east of Madagascar. It ranks among the strangest of the region's lost birds because it is known almost entirely from the written accounts of travellers, hunters and colonists who saw it between roughly 1660 and the mid-1700s. No mounted specimen was ever preserved, and confirmed bones have proven maddeningly hard to pin down, so the species hovers between solid history and tantalizing mystery.
What the eyewitnesses described was memorable: an entirely blue bird about the size of a large chicken, with a bright red bill and red legs, that ran swiftly through the upland plains and flew poorly if at all. Naturalists later gave it the scientific name Porphyrio coerulescens, grouping it with the swamphens, the same widespread genus that includes the living purple swamphens and New Zealand's takahe. Like so many flightless island birds that had never learned to fear people, it was easy prey. Within a few decades of permanent settlement, hunting and introduced animals had wiped it out.
Because the Réunion Swamphen vanished before anyone described it scientifically, its appearance is known only from period travellers' reports rather than measured specimens. Those accounts are remarkably consistent, however. They describe a stout, upright, chicken-sized bird that was wholly blue, set off by vivid red bare parts, and that moved on the ground with speed and confidence. Observers repeatedly stressed how well it ran and how reluctantly it flew, a classic profile for a swamphen on a predator-free island.
| Size | Reported around 65 to 70 cm long, roughly the bulk of a large chicken |
| Plumage | Described by every observer as entirely blue, with no strong markings noted |
| Bill | Large, stout and bright red, typical of the swamphen genus |
| Legs & feet | Long, sturdy and red, built for running over open highland ground |
| Flight | Weak and rarely used; the bird was probably flightless or nearly so |
| Overall shape | Upright, heavy-bodied rail with a short tail, resembling a small takahe |
Male vs. female
No historical observer distinguished males from females, and nothing is known about whether the sexes differed in size or color. Among living swamphens the sexes look essentially alike, with males often only slightly larger, so any difference in the Réunion bird was probably subtle. Given how briefly the species overlapped with literate settlers, and how little interest early accounts took in such details, it is unlikely we will ever know whether the oiseau bleu showed any visible difference between the sexes.
Juveniles
The young of the Réunion Swamphen were never described. In related swamphens, chicks hatch covered in blackish down and are precocial, able to leave the nest and follow their parents within a day or two while remaining dependent for food for some weeks. By analogy, young oiseaux bleus were most likely dark, downy and mobile from hatching, gradually acquiring the blue plumage of adults. This is an inference from close relatives, not something any observer recorded, and it should be read with that caution.
No description of the Réunion Swamphen's voice survives. As a member of the swamphen and rail group, it very probably had loud, harsh, far-carrying calls, similar to the shrieks, cackles, grunts and booming notes produced by living Porphyrio swamphens, which use such sounds to defend territory and stay in contact through dense cover. All of this, however, is inferred from its relatives. The actual sounds of the oiseau bleu are lost, and any confident claim about its calls would go beyond the evidence.
The Réunion Swamphen was found only on Réunion, a single volcanic island in the western Indian Ocean about 175 km southwest of Mauritius. It occurred nowhere else on Earth, an extreme example of the narrow ranges typical of Mascarene endemics. Within the island, historical accounts consistently place it away from the coast, in the elevated interior. Observers described it on the high plains and marshy uplands of the mountainous centre, most famously the Plaine des Cafres and similar highland basins between the island's great volcanic massifs.
This upland distribution may partly explain how it survived the first years of settlement, since coastal areas were colonized and hunted first. It also sealed its fate, however, because as settlers, escaped livestock and introduced predators spread into the interior, the bird had no other refuge and nowhere else to go. Being restricted to one island, and then to its highlands, left the species with no buffer against a shrinking, increasingly dangerous range.
The diet of the Réunion Swamphen was never recorded in any detail, so it must be reconstructed from its swamphen relatives. Living Porphyrio swamphens are broad, opportunistic feeders. They pull up and eat the shoots, stems, roots and seeds of marsh and grassland plants, often gripping food in one foot to bite off pieces, and they readily supplement this vegetable diet with insects, snails, worms, eggs and other small animals when the chance arises.
The Réunion bird, with its stout red bill and highland marsh habitat, was almost certainly a similar generalist, grazing and probing through wet upland vegetation for plant matter and small invertebrates. Its tameness toward people, so often remarked upon by hunters, suggests a bird that had evolved with few natural enemies and foraged in the open without much fear.
Nothing was ever recorded about the breeding of the Réunion Swamphen, including its nest, eggs, clutch size or season. Everything below is inference from close relatives rather than observation. Living swamphens build bulky, trampled platforms of reeds, grasses and other vegetation, usually hidden low in dense marsh growth near water, and lay clutches of several spotted eggs. Both parents, and sometimes additional helpers, share incubation and the care of the precocial young.
If the oiseau bleu followed this pattern, it likely nested on or near the ground in the marshy highland vegetation where it lived, which would have made its eggs and chicks tragically easy prey for introduced rats, cats and pigs. Ground nesting is a common thread among the flightless island birds that introduced mammals drove to extinction, and it may well have hastened this one's disappearance.
The Réunion Swamphen has been extinct for nearly three centuries, so there is no way to see one in life. What you can do is seek out its closest living relatives and visit the island it once called home. The following are honest ways to connect with the story of the oiseau bleu and with the swamphens that still survive.
- See a living relative: the takahe of New Zealand is the large flightless swamphen most often compared to the Réunion bird, and it can be seen at sanctuaries such as Zealandia and on predator-free islands.
- Watch a purple or Australasian swamphen in the wild across Europe, Africa, Asia and Australasia to picture the red bill, red legs and confident gait the oiseau bleu shared.
- Visit Réunion itself, especially the highland Plaine des Cafres, to walk the upland landscape where the blue bird once ran.
- Explore Réunion's surviving endemics, including the Réunion cuckooshrike and Réunion harrier, whose conservation is the living continuation of this island's natural history.
- Read the primary travellers' accounts and modern reviews of Mascarene extinctions to understand how much, and how little, we truly know about this bird.
- Support island predator-control and habitat programs, the exact conservation work that keeps relatives like the takahe from following the oiseau bleu into extinction.
- Takahe: Large flightless swamphen of New Zealand thought to resemble the extinct Réunion bird
- Australasian Swamphen: Living blue-and-black swamphen with a red bill, a likely relative of the Réunion species
- Western Swamphen: Purple-blue rail of the Old World with red bill and legs, similar in form
When did the Réunion Swamphen go extinct?
It is generally thought to have died out around 1730, though some accounts suggest scattered birds may have survived into the 1760s. Hunting by settlers and predation by introduced cats, rats and pigs are considered the main causes.
Did the Réunion Swamphen really exist?
Almost certainly. It is sometimes labelled a hypothetical species because no undisputed physical remains have been confirmed, but several independent eyewitnesses described the same distinctive blue, red-billed bird, and most researchers accept it as a genuine extinct swamphen.
What did it look like?
Historical observers described an entirely blue bird about the size of a large chicken, with a stout red bill and long red legs, that ran well but flew poorly or not at all. It may have resembled a smaller version of New Zealand's takahe.
Why are there no specimens or skeletons?
Réunion was settled and its wildlife hunted before organized scientific collecting existed, and the bird vanished quickly. No bones have been definitively matched to it, so nearly everything we know comes from written travellers' reports.
What is the closest living relative I can actually see?
The takahe of New Zealand, a large flightless swamphen, is the relative most often compared to the Réunion bird and can be seen at predator-free sanctuaries. Widespread purple and Australasian swamphens also share its red bill and legs and are far easier to find.
Why did so many Mascarene birds like this one die out?
Islands such as Réunion, Mauritius and Rodrigues had birds that evolved without ground predators, so many were tame and flightless. When people arrived with cats, rats and pigs and hunted the birds directly, species like the oiseau bleu and the famous dodo had no defences and disappeared fast.