Ornithologists have described a newly identified bird species inhabiting the sub-arctic islands off South America. The discovery is part of a broader study described in the N+1 version of the report.
The research team led by Ricardo Rozzi from the University of Magallanes and colleagues examined the spiny-tailed rayadito, a small insectivorous passerine found at the southern limits of Argentina and Chile. A distinct, isolated population lives on the Diego Ramirez archipelago in the Drake Passage, separated from the mainland by a broad ocean expanse. On these islands, the birds adapted to dwelling among tall grasses rather than tall trees.
To investigate, researchers captured thirteen individuals from the island population, weighing them and taking measurements of beak length and width, wing length, claw length, and tail length. These were then compared with mainland relatives. The results showed that Diego Ramirez islanders weighed about a quarter more than Tierra del Fuego birds, yet possessed shorter tails. The island birds also exhibited longer and wider beaks and longer claws. Wing length, however, was similar between the Diego Ramirez archipelago group and those from Tierra del Fuego. The team noted that raiaditos from the Beagle Channel shores and Navarino Island share a similar morphology, while the Diego Ramirez birds form a separate cluster in the analysis.
In modern biology, DNA is the primary criterion for classifying organisms. The Diego Ramirez population appeared genetically isolated with a high level of inbreeding. Behavioral observations highlighted notable lifestyle differences as well. On the archipelago, these rayaditos feed primarily on grasses at ground level, rarely fly to higher elevations, and often lay eggs in earthen nests created by other birds. Scientists propose that the combination of larger body size and shorter tails in this local population is tied to these ecological habits. In contrast, mainland relatives forage for insects among trees and nest in hollows within them.
Taking all evidence into account, the researchers proposed recognizing the island population of rayaditos as a distinct species. The proposed name for this new taxon is the Subantarctic rayadito.
A separate note from the paleobiology record mentions that some Ecuadorian whales have begun to emit long scent-like songs that resemble those of their distant relatives across the ocean, a reminder of how interconnected marine life can be across vast distances.