The volcanic islands of the Azores are unique and beautiful: covered with temperate forests, spotted with craters and hot springs, and home to numerous species of plants and animals not seen anywhere else. But this enticing archipelago isn't quite what it used to be. A trip through the wilderness will reveal a mixture of introduced critters like rats and weasels, alongside native species in severely diminished numbers.

A new study shows that for some of the Azores' animal inhabitants, the threat posed by humans and invasive species was already being felt hundreds of years ago. A recently discovered extinct songbird was one of them.

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Reconstruction (left) of the extinct bullfinch, named Pyrrhula crassa, and its skull (right). Credit: Pau Oliver

On the southeast portion of Graciosa Island lies a 12,000-year-old volcano called Caldeira, and inside its volcanic crater is a small and formerly lava-filled cavern called Furna do Calcinhas. It is within this chamber that researchers discovered the bones of the skull, wings and other parts of an ancient species of bullfinch.

Comparing the bird to its living relatives, the scientists found that it was a previously unknown species, and the largest of the bullfinches. It's now been officially named Pyrrhula crassa.

"Its short, wide beak was not just considerably bigger, but also relatively higher than that of the common bullfinch ... with a very robust configuration reminiscent to an extent of the beak of a small parrot," said Josep Antoni Alcover of the Mediterranean Institute for Advanced Science, one of the authors of the study describing the new discovery. 

As for the living Azores bullfinch, it's not doing too well today. Thanks to a history of habitat loss and the introduction of invasive predators and alien vegetation, its population numbers have suffered, like many of the species in the archipelago and on islands around the world. And just like many other island species, there's only one place on earth these birds call home.

Human habitation on the Azores goes back at least to the 1200s, when Portuguese explorers landed and established settlements there. The new bullfinch species may very well have gone extinct due to the newcomers' arrival: even back then, humans were in the habit of rapidly cutting and burning down forests, and introducing – accidentally or intentionally – invasive species of plants and animals.

This is actually a trend seen all across the fossil record: when humans arrive on islands, local species tend to disappear from history, whether it's the Galapagos, Hawaii, the Canary Islands or elsewhere. The research team expects to find more evidence of this pattern as they continue to explore the ancient remains and fossils of the Azores.

"It is the first extinct passerine bird described in the archipelago," said Alcover, "and it won't be the last."



Top header image: Pau Oliver