White-crested Tyrannulet

The white-crested tyrannulet (Serpophaga subcristata) is a small species of bird in the family Tyrannidae, the tyrant flycatchers. It is found in Argentina, Bolivia, Brazil, Paraguay, and Uruguay. == Taxonomy and systematics == The white-crested tyrannulet was originally described as Sylvia subcristata, thought to be a member of what at the time was the Old World warbler family. The white-crested tyrannulet has three subspecies, the nominate S. s. subcristata (Vieillot, 1817), S. s. munda (Berlepsch, 1893), and S. s. straminea (Temminck, 1822). Subspecies S. s. munda was originally described as a full species. BirdLife International's Handbook of the Birds of the World lumped it into the white-crested tyrannulet in 2020. The Clements taxonomy followed suit in 2022 as did the South American Classification Committee of the American Ornithological Society and the International Ornithological Committee in 2023. In addition, what is now Straneck's tyrannulet (S. griseicapilla) was long confused with the white-crested tyrannulet but was eventually recognized as a full species based largely on their very different vocalizations. == Description == The white-crested tyrannulet is 11 cm (4.3 in) long and weighs 6 to 8.6 g (0.21 to 0.30 oz). The sexes have the same plumage. Adults of the nominate subspecies…