Aphrastura is a small genus of terrestrial passerine birds in the ovenbird family Furnariidae.
Commonly known as rayaditos, these birds are endemic to southwestern South America.
Aphrastura includes two previously-known species: the thorn-tailed rayadito (Aphrastura spinicauda) and the Masafuera rayadito (Aphrastura masafuerae).
The former species inhabits the temperate forest biome of the South American continent, and the latter’s distribution is limited to the misty tree fern forests of the oceanic Alejandro Selkirk Island.
“The Alejandro Selkirk Island has an area of only 85 km2 and is part of the Juan Fernández Archipelago, separated from the continent by 670 km,” said Dr. Ricardo Rozzi, a researcher at the Universidad de Magallanes and the University of North Texas, and his colleagues.
“Unlike the Masafuera rayadito, the thorn-tailed rayadito has a broad distribution along the entire latitudinal range of the South American temperate forests’ biome.”
“It inhabits deciduous and evergreen forest types ranging from north-central Chile to the extreme south of Chile and Argentina.”
The newly-identified species, named the subantarctic rayadito (Aphrastura subantarctica), inhabits the Diego Ramírez Archipelago.
“The Diego Ramírez is the southernmost point of the South American continent,” the researchers said.
“While emerging only 100 km southwest of Cape Horn on the margin of the continental shelf, the archipelago is separated from it by one of the world’s roughest seas in the northern section of the Drake Passage, with harsh climatic conditions and difficult access from the continent.”
The subantarctic rayadito has a total length of 14.5 cm and weighs about 15 grams.
The species differs from the thorn-tailed rayadito by its larger beak, longer tarsi, shorter tail, and larger body mass.
It moves at shorter distances from ground level, and instead of nesting in cavities in trees, it breeds in cavities in the ground, reflecting different life-histories.
“The genetic, morphological, and ecological divergence of the subantarctic rayadito population, which may have resulted from isolation on an island with a distinct habitat, is probably an ongoing evolutionary process,” the authors said.
“Because of the small size of the Diego Ramírez islands and the potential arrival of exotic mammal predators, it is pressing to protect this new endemic species from extinction.”
The discovery of the subantarctic rayadito is reported in a paper in the journal Scientific Reports.
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R. Rozzi et al. 2022. The subantarctic rayadito (Aphrastura subantarctica), a new bird species on the southernmost islands of the Americas. Sci Rep 12, 13957; doi: 10.1038/s41598-022-17985-4
This article by Natali Anderson was first published by Sci.News on 29 August 2022. Lead Image: The subantarctic rayadito (Aphrastura subantarctica). Image credit: Rozzi et al., doi: 10.1038/s41598-022-17985-4.
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