White-crested Tyrannulet (Serpophaga subcristata) [XC486111]
by Guillermo Treboux from Estancia La Candelaria, Lobos, Buenos Aires, Argentina (call)
White-crested Tyrannulet (Serpophaga subcristata) [XC686540]
by Fernando Igor de Godoy from Parque Estadual do Esphinillo Barra do Quara\u00ed, Brazil (call, song, hatchling or nestling)
Subspecies
Taxonomic status controversial. Sometimes considered conspecific with White-bellied Tyrannulet (Serpophaga munda), but the two differ in plumage, also slightly in voice, and in Argentina are narrowly parapatric with limited hybridization. Further study is required.
The following 2 subspecies are recognised:
subcristata (Vieillot, 1817) - Bolivia (from northern La Paz) and southern Brazil (southern from southern Mato Grosso) south through Paraguay to Argentina (south to northern Chubut).
straminea (Temminck, 1822) - South-eastern Brazil (southern Piauí and Bahia south to Rio Grande do Sul) and Uruguay.