Serra Antwren

The serra antwren (Formicivora serrana) is a species of small insectivorous bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is endemic to southeastern Brazil. == Taxonomy and systematics == The serra antwren has these three subspecies according to worldwide taxonomic systems: F. s. serrana (Hellmayr, 1929) F. s. interposita Gonzaga & Pacheco, 1990 F. s. littoralis Gonzaga & Pacheco, 1990 Subspecies F. s. littoralis was originally described as a subspecies of the serra antwren but was later separated as a species, the "restinga antwren". A study published in 2011 showed little or no vocal differences among serrana, interposita, and littoralis and only minor morphological differences between interposita and littoralis. The worldwide taxonomic systems therefore restored littoralis to subspecies status. The South American Classification Committee of the American Ornithological Society retains the serra and restinga antwrens as separate species but is urgently seeking a formal proposal to combine them. == Description == Antwrens in the genus Formicivora have comparatively long tails, and the males are unusual in having underparts that are darker than the upperparts. The serra antwren is 12 to 14 cm (4.7 to 5.5 in) long and weighs 10 to 13 g (0.35 to 0.46 oz).…