Variable Antshrike

The variable antshrike (Thamnophilus caerulescens) is a species of bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is found in Argentina, Bolivia, Brazil, Paraguay, Peru, and Uruguay. == Taxonomy and systematics == The variable antshrike was described by the French ornithologist Louis Pierre Vieillot in 1816 and given its current binomial name Thamnophilus caerulescens. Major taxonomic systems assign these eight subspecies to the variable antshrike: The variable antshrike's highly variable plumage, some variations in the voice, and its unusual distribution have resulted in widespread speculations that it involves more than one species. Studies involving mtDNA and voice of the Bolivian populations, which is a meeting point for several of the distinctly different subspecies, did not support the theory of several species, instead suggesting that much of the vocal variation is clinal. and geneflow between various populations remains uninterrupted. Subspecies T. c. cearensis in northeastern Brazil, which also is relatively distinctive, was not included in these studies, and it therefore remains unclear if it is worthy of species recognition. Another problem relates to the variations within subspecies. The subspecies dinellii and cearensis, for example, are both variable, resulting in some authors proposing additional subspecies within the widely accepted…