Eighty years ago, Charles Darwin made one final stop with the HMS BeagleattheAzores, a remote mid-Atlantic archipelago.In his journal Darwin described the islandsas being populated by “some old English friends”: starlings, wagtails, chaffinches, and blackbirds. But little did he know that lying below his feet were the remainsof birds as unique as the Galapagos finches.
Now, a few of thespeciesthat eluded Darwin havefinallybeenrevealed. Last December,Josep Antoni Alcover, a zoologist at the Mediterranean Institute for Advanced Studies, and agroup of European biologists and paleontologists identified the bones ofsixpreviously undiscovered species of rails that went extinct on the Azores and the nearby archipelago of Madeira. The most modern of the bunch died out nearly600 years ago, the scientistsestimate in their recent article published in.“If [Darwin]had visited the islands 500 years earlier, hecould have seen different endemic rails, endemic quails, endemic little-owls, endemic finches, endemic pigeons, endemic thrushes, endemic wrens, and huge quantities of seabirds,” Alcover says.
The new species, which the researchers believe evolved independently from the common (still-living)ancestorRallus aquaticus,include a slender rail from Porto Santo, a small rail from Pico, a short-legged rail from São Miguel, and a minute rail from São Jorge. The researchers also identified a plump rail on Madeira, along witha sixthspecies, currently unnamed, preserved in silica on Terceira.
A Band of Flightless Birds
of the sixnew rail speciesare thought to have beenflightless.By studying the structure of the fossils, the scientists discovered thatthe Pico rail was the only one withaerial abilities—and even those were limited. All of therails were probably airborne at first; but soon after they spread out and seemingly conquered the islands, theydevelopedshort legs, weak wing bones, and other signs of flightlessness. The theory is that the islands were sofilled with fish, insects, crustaceans, and grassy nesting habitat thatthe rails didn’t find the need to fly anywhere else.
Flightlessness does appear to have come at a cost, however. The researchers point out that the rails’ extinctions may have coincided with the arrival of human colonizers. It's to otherisland bird species that have lost the ability to fly—most notably the Dodo. “They had restricted distribution areas,” says Alcover. “They bred on the ground. They evolved without terrestrial predators. All together [this] made them very vulnerable to the ecological changes that started with the humans’ arrival."
WhichRails Have Survived?
Today, there are 100-plus rail speciesspread out acrossthe world.Only a feware flightless andindigenous,isolated to obscure islands, such as Tristan da Cunha and Gough. The rest are migratory. All rails, both flightless and flighted, are elusive—quiet and hard to spot among the tall reeds and dark muck of their wetland habitats. Most birders “either love them or hate them” because of the challenge they present when it comes to spotting them,says, a PhD student at the University of Arkansas and associate wildlife biologist at Arkansas Cooperative Fish and Wildlife Unit, who wasn’t involved with the study.
Given their history with humans, it makes sense that modernrails stick to themselves and toisolated habitats.That’s why it's necessaryto preserve these types of places, Alcover says,so that unique species—like rails—aren’t lost forever.
“There’s a lot we don’t know about rails,”Fournier adds. “This study sheds a little more light on these cool and charismatic, yet covert, birds.”
Correction: Due to an editing error, the story previously said that there are only 13 species of rails left in the world.