Ornithologists have described a new bird species from the subantarctic islands

Ornithologists have described a new species of bird that lives on the Diego Ramirez Islands south of South America. It is called the subantarctic rayadito. In the past, the local population was thought to be the spiny-tailed rayadito, which is widespread in Chile and Argentina. However, the analysis showed that individuals from the Diego Ramirez Islands are larger and behave differently: instead of climbing trees and building nests in hollows, they hide from the wind in tall grass and hatch chicks in abandoned seabird burrows. A description of the new species was published in an article for the magazine Scientific Reports.

Ornithologists know about eleven thousand species of birds, and thanks to new discoveries, this list is replenished from time to time. For example, last year experts described a previously unknown genus and species of birds from Bolivia and Peru – the brightly colored sun tanager (Heliotraupis oneilli). However, much more often ornithologists do not discover completely new species, but split up already known ones, based on genetic and morphological analysis. So, about ten years ago, a red-bellied pitta (Erythropitta erythrogaster), widespread from the Philippines to northern Australia and Melanesia, has been divided into thirteen separate species. One of them, Louisiada pitta (E. meeki), only recently discovered after a hiatus of more than a hundred years.

Another new species of bird was described by a team of ornithologists led by Ricardo Rozzi from the University of Magalhaes. The focus of researchers' attention was the spiny-tailed rayadite (Aphrastura spinicauda) are small insectivorous representatives of the furnace family (Furnariidae), living in the forests of Chile and Argentina. One of the populations of this species inhabits the subantarctic Diego Ramirez archipelago, which is located in the Drake Passage and is considered the southernmost point of Chile and South America. Local rayaditos are isolated from their mainland relatives by the stormy ocean. In addition, they differ from them in environmental preferences. Since there are no forests or trees on the archipelago, the rayaditos here live in tall grass – thickets of bluegrass fan-shaped (Poa flabellata).

Rozzi and his colleagues decided to clarify the taxonomic status of the rayadito from the Diego Ramirez archipelago. To do this, they caught thirteen representatives of this population, weighed them and measured the length and width of their beaks, as well as the length of their wings, legs and tail. In a similar manner, the authors examined the morphological characteristics of 104 mainland rayaditos from two regions of Tierra del Fuego: from the shores of the Beagle Channel and from the island of Navarino. It turned out that individuals from the Diego Ramirez Islands are a quarter heavier than their relatives from Tierra del Fuego, but their tails are shorter. In addition, island birds have longer and wider beaks and longer legs. At the same time, the length of the wings of individuals from the Diego Ramirez archipelago and from Tierra del Fuego does not differ. The authors note that rayaditos from the shores of the Beagle Channel and from Navarino Island are morphologically similar to each other, while their relatives from the Diego Ramirez Islands form a separate cluster.

In the next step, the researchers compared the mitochondrial DNA of 120 rayadites from across the species' range, from central Chile to the Diego Ramirez archipelago. The analysis confirmed the isolated position of the population from the subantarctic islands. By comparison, individuals from Tierra del Fuego are not isolated from other South American populations. In addition, the rayaditos from the Diego Ramirez Islands were found to have low genetic diversity. Compared to other populations, they exhibit the least heterozygosity, the highest inbreeding coefficient, and the lowest allelic diversity.

Rozzi and co-authors also conducted field observations of raiadito from the Diego Ramirez Islands. On Gonzalo, the second largest island of the archipelago, researchers noted 47 of these birds per kilometer of the survey route. Almost all the rayaditos held on and looked for food in the tall grass that protected them from the wind, flying short distances and not rising high above the ground. It is possible that the larger body weight and shorter tails characteristic of representatives of the local population are associated with these behavioral features. Ornithologists were able to find ten rayadito nests, half of which were located in burrows dug by seabirds or natural cavities in the soil. In comparison, mainland rayaditos forage in trees and nest in hollows. Ornithologists note that the Rayaditos from Diego Ramirez are ecologically similar to wrens (Troglodytidae), while birds from South America are more likely to occupy the niches of tits (Paridae) or pikas (Certhiidae).

Since the Rayadito from the Diego Ramirez Islands are noticeably different from their mainland relatives morphologically, genetically and ecologically, Rozzi and his colleagues proposed to distinguish this population as a separate species. It was named subantarctic rayadito (Aphrastura subantarctic). This is the second island species of the genus Aphrastura: first, island rayadito (A. masafuerae) lives on Alexander-Selkirk Island in the Juan Fernandez Archipelago and is on the verge of extinction due to invasive predators. Alien species have not yet arrived in Diego Ramirez, so the native rayaditos are safe for now. However, Rozzi and his co-authors are calling for increased control over the biological safety of the archipelago to ensure that the new bird species is not harmed by rats, cats or American minks, which may get here along with people.

Previously, we told how two species of Turkic birds were caught in their love for truffles and other mushrooms. Having gone to the temperate forests of Chile, where these birds live, biologists found them searching for and eating mushrooms. Analysis of the Turko's droppings confirmed that they regularly eat a variety of mushrooms and spread their spores throughout the forest.

Sergey Kolenov

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