Fan-tailed Warbler

Overview

The fan-tailed warbler (Basileuterus lachrymosus) is a species of New World warbler found from Mexico to Nicaragua. It is generally considered a year-round resident, though some northern populations may withdraw south in winter. The species is assessed as Least Concern by the IUCN, with an estimated population of at least 50,000 mature individuals.

Identification

• Approximately 15 cm long with a dark gray face featuring a black forecrown, narrow yellow crown patch, and white lores spot.
• Upperparts are dark gray with a faint olive wash; throat, breast, and belly are rich yellow with tawny-flanked sides.
• Long, graduated dark gray tail with white feather tips; the bird exhibits a distinctive habit of constant tail-fanning and tail-swinging.
• Song consists of a series of clear, downslurred whistles, such as "wee wee wee wee wee wee-cher", or "see'sah'see'sah'see'seew'seew".

Habitat

Found on the Pacific and Gulf slopes of Mexico, extending south to central Nicaragua, and occasionally as a vagrant in the southern United States. It inhabits semi-deciduous and evergreen forests with intact understories in foothills and lower mountain slopes, favoring rugged, rocky areas like ravines and lava flows. Elevation ranges from 50 to 1,850 m.

Diet

Feeds on insects and other invertebrates, gleaning prey from leaves and rocks on the ground or in low vegetation. It regularly attends army ant swarms and may follow nine-banded armadillos to capture fleeing insects. In the non-breeding season, it may join mixed-species feeding flocks.

Did you know?

The species has a complicated taxonomic history, with its genus classification shifting between Basileuterus and Euthlypis due to conflicting molecular studies and authorities. As of 2025, the American Ornithological Society returned it to Euthlypis, while other systems retained it in Basileuterus.