New wren from Colombia

Antioquia Wren, a dry scrub specialist, is already classified as Vulnerable due to the planned damming of its valley habitat. Photo: Carlos Esteban Lara
Antioquia Wren, a dry scrub specialist, is already classified as Vulnerable due to the planned damming of its valley habitat. Photo: Carlos Esteban Lara

A new species of wren has been named from north-western Colombia, which had remained undiscovered despite being present in a fairly popular birding  tour destination.

The bird – named Antioquia Wren Thryophilus sernai  – had been heard singing in the Bolombolo area by a number of visiting groups recently and was misidentified as Rufous-and-white Wren T rufalbus, despite that species' range not extending to any of the sites. The area is popular for several localised Colombian endemics.

The new wren is isolated from other near relatives in the Cauca River Canyon in the Andes mountains, surrounded by highland rain forest. The bird lives mostly along watercourses in remnant patches of semi-deciduous dry forest and scrub at between 250 and 850 m and, though anecdotally "not uncommon", its limited range and shrinking habitat, as well as the planned damming of part of the valley, mean that it is already viewed to be threatened with extinction. It appears to fit the criteria for classification as Vulnerable and the authors recommend immediate conservation action.

Main author Carlos Esteban Lara discovered Antioquia Wren on 26 February 2010, when he noted an unidentifiable Thryothorus-like wren in a narrow stretch of the Cauca Valley where none had been recorded before. Its true affiliations only emerged when he and his assistants made further observations in the field.

The Cauca River Valley in north-western Colombia provides the sole habitat and home for the new wren species. Photo: Carlos Esteban Lara

Three specimens were taken , including an adult male as a type specimen for morphometrics, mitochondrial cytb gene sequences were sampled and deposited with Genbank, and a recording of the voice was also lodged with the Banco de Sonidos Animales, Instituto Alexander von Humboldt, Boyacá, Colombia. The new species is apparently readily separable from its nearest congeners on both voice and plumage. Another adult male and an adult female were also taken as paratypes.

Antioquia Wren can be told from other Thryophilus species by its pale, cinnamon-brown upperparts, fine dark barring on the wings and tail with spotting at the end of the main feathers, a narrow white supercilium, brownish streaking on the cheeks and pale brown underparts with dull brown flanks. It is smaller than its potential confusion species, with shorter wings and a longer tail than T rufalbus.

Phylogenetic analysis suggests that the bird has probably been isolated from its congeners for up to two million years and is a valid species under the phylogenetic species concept , and its geographical isolation and distinctive plumage and vocalisations imply reproductive isolation, too,  enabling justifiable splitting under the biological species concept. Its closest relative appears to be Niceforo's Wren Thryophilus nicefori, found in a relatively nearby branch of the same mountains, or the more widespread Rufous-and-white Wren.   

Lara, C E, Cuervo, A M, Valderrama, S V, Caldéron-Franco, D and Cadena, C D. 2012. A new species of wren (Troglodytidae: Thryophilus) from the dry Cauca River Canyon, Northwestern Colombia. The Auk in press.
Also Caldéron-Franco, D (2012). Internet forum posting at: www.birdforum.net/showpost.php?p=2454301&postcount=9