Description wikipedia

The fan-tailed warbler (Basileuterus lachrymosus) is a New World warbler in the genus Basileuterus that lives along the Pacific slope from northern Mexico to Nicaragua. Vagrant records exist for Arizona, New Mexico and Texas. It is yellow on its throat and underparts with a tawny wash on its chest. The head is gray with a black-framed yellow crown and white around the eyes. The undertail coverlets are white. It is 5.8-6.3 in (14.5–16 cm) long and has a pleasant, upslurred song. Fan-tailed warblers live in and at the edge of evergreen and semideciduous forest, especially near ravines. They eat insects, and are seen hopping around on either the forest floor or close to it. They are found alone or in pairs. Fan-tailed warblers are known to engage in commensal feeding, wherein prey that has been roused or disturbed by the foraging or hunting of another animal is opportunistically captured. They have been observed following and foraging for prey near army ants, other passerines, and nine-banded armadillos. The fan-tailed warbler was formerly placed in the monotypic genus Euthlypis due to its unique morphology, but its nest, eggs, voice, and juvenile plumage are consistent with Basileuterus. A molecular phylogenetic study published in 2010 found that the fan-tailed warbler was basal to the other species in the genus Basileuterus. In contrast, a 2024 molecular phylogenetic study found that the fan-tailed warbler was sister to a clade containing the genera Myioborus, Cardellina, and the remaining Basileuterus species.