BIRD FAMILIES OF THE WORLD
 
 
a web page by Don Roberson
 
 
ELACHURA Elachuridae
  • 1 species in southern Asia
  • DR personal total: 0 species (0%), 0 photo'd

"The past 10 years have witnessed a surge in taxonomic changes in Asian birds, partly as a result of molecular analyses," wrote Per Alström and coauthors in Biology Letters in 2014. One of the most surprising was that White-bellied "Yuhina," a common bird throughout much of tropical Asia, and well-ensconsed within the Babblers, was actually related to Vireos in the New World (Cibois 2003, Alström et al. 2006); see the Erpornis page. Now something even more shocking has been discovered.

Alström et al. (2014) were interested in the evolution of Asian babblers. The international team amassed a huge DNA sequence dataset for the Passerida, which represents about 60% of global bird species. They found the Passerida was composed of ten clades [evolutionary lineages], nine of which were expected. But on a single "bare branch" at the base of the evolutionary tree was something totally unexpected — a tiny "wren-babbler," traditionally known as Spotted Wren-Babbler "Spelaeornis formosus," which had recently been moved to its own genus (Elachura) because of distinctive morphology and vocalizations (Collar & Robson 2007).

Here (left, in an amazing shot by Roon Bhuyan) is Elachura, now described by Alström et al. (2014) as the only extant member of the ancient family Elachuridae.

Elachura is, to quote a blog by "grrlscientist" in The Guardian in April 2014, a "little brown bird that is so shy that it's heard more often than seen as it goes about its business in dense moist forests throughout the mountains of tropical and subtropical Asia." It is usually located by its distinctive vocalization, and it does hide in the undergrowth, where it is a local resident within its range. This map (right) is from Alström et al. (2014) and shows the range of Elachura in red: eastern Himalayas extending down mountain chains into Burma and Vietnam, and an isolated range in the mountains of southeast China. The three black (and named) dots on the map where the locations of specimens analyzed by Alström et al. (2014).

The "grrlscientist" blog interviewed Per Alström about the discovery of this unique little bird. He said that he doubted "that we'll find another species that belongs in the same family. So the Elachura is likely to be a true loner." It managed to avoid detection as a unique family for so many years because of the "wonders of convergent evolution," which permit unrelated species to evolve to resemble each other because they occupy similar niches.

As to seeing one in the field, Alström himself had seen it in both India and China, but added "It's extremely difficult to watch, as it inhabits dense undergrowth, often in little gullies on very steep mountain slopes." As to finding one: "All of the ones that I've seen I've first noticed by their distinctive song."

There were once a half-dozen or so other genera that were called wren-babblers but it is truly remarkable that when genetic analysis was undertaken, two of them were not babblers at all. Elachura proved to be this ancient lineages, and the genus Pnoepyga, sometimes called the "pygmy wren-babblers," were also not babblers and were elevated to the Pnoepygidae, the Cupwings. Will there be more surprises? It seems unlikely. The DNA evidence published so far has found that the remaining wren-babblers with the family Timaliidae, but that there they divide yet again: genus Spelaeornis is within the subfamily Timaliinae while the remaining genera termed wren-babblers (e.g., Rimator, Ptiolcichla, Kenopia, Napothera) are now assigned to this subfamily Pellorneinae. Several major world checklists (e.g., Clements, IOC) currently elevate what I recognize as three subfamilies of Babblers to three Family-level groupings. In that scenario, the "old" wren-babblers have proven to belong to four (!!) different families.

 

Photos: The Elachura Elachura formosa was photographed in Arunachal Pradesh, India.

      Photo © Roon Bhuyan, as credited, and used with permission; all rights reserved. I am grateful to Murray Lord, Tony Paliser, and Abidur Rahman for help in obtaining permission to use this very nice photograph.


Bibliographic note: There is no "family book" on this new family, but a good introduction to the genus, with photos, is in Collar & Robson (2007).

Literature cited:

Alström P., P.G.P. Ericson, U. Olsson, and P. Sundberg. 2006. Phylogeny and classification of the avian superfamily Sylvioidea. Molecular Phylogenetics & Evolution 38: 381-397.

Alström. P., D.M. Hooper, Y. Liu, U. Olsson, D. Mohan, M. Gelang, L.M. Hung, J. Zhao, F. Lei, and T.D. Price. 2014. Discovery of a relict lineage and monotypic family of passerine birds. Biol. Letters 10 (3) doi:10.1098/rsbl.2013.1067

Cibois, A. 2003. Mitochondrial DNA phylogeny of babblers (Timaliidae). Auk 120: 35-54.

Collar, N. J. and C. Robson. 2007. Family Timaliidae (Babblers) pp. 70–291 in Handbook of the Birds of the World J. (del Hoyo, A. Elliott, & D.A. Christie, eds.). Vol. 12. Lynx Edicions, Barcelona.

 
 

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