Fan-tailed Warbler, Basileuterus lachrymosus
Fan-tailed Warbler, Basileuterus lachrymosus. Photograph taken within the Reserva Monte Mojino, in Alamos, Sonora, May 2018. Photograph and identification courtesy of David F Smith, Alamos, Sonora.
Background and Identification
The Fan-tailed Warbler, Basileuterus lachrymosus, is a mid-sized member of the Parulidae Family of New World Warblers, which has one hundred eleven individual species that have been placed into eighteen genera, and one of twelve global members of the Basileuterus Genus. Their song consists of a series of rich, whistling notes, often heard in dense forest undergrowth where they forage for insects. They are known in Mexico as Chipe de Roca.
The Fan-tailed Warbler is mid-sized. The sexes are similar in appearance and size, known as sexual monomorphism. Adults have a length of approximately 14 cm (5.5 in). They have a bright yellow underside, an olive-brown back, and a bold black-and-white facial pattern, which includes a striking black stripe through the eye and a white supercilium (eyebrow). Their bills are long and black, their iris is dark, and their legs are dusky pink. One of their most distinctive features is their habit of flicking and fanning their long, rounded tail, which has white outer feathers that are often visible in motion.
Habitat and Geographical Range
This species is found in submontane and lower montane evergreen and semi-deciduous forests within undisturbed understory in rocky areas and forest-covered lava flows in the foothills and lower mountains at elevations between 50 m (165 feet) and 1,800 m (5,900 feet). They are ground foragers that feed as individuals, in pairs or in mixed-species flocks that consume insects and other invertebrates that are known to follow swarms of army ants, feeding on invertebrates that flee the ants, and Nine-banded Armadillos. The Fan-tailed Warbler has been poorly studied and very limited information about their behavioral patterns and biology has been documented.
The Fan-tailed Warbler is found in northern Mexico from northwest Baja California to Tamaulipas and south to northwestern Nicaragua. Most are non-migratory but some of the northern populations winter in the south.
Common Misidentifications
The Fan-tailed Warbler is structurally similar to the Yellow-breasted Chat, Icteria virens. However, the Fan-tailed Warbler can be distinguished by:
- bold black-and-white facial markings (more pronounced than in similar species).
- habit of fanning its tail is uncommon among other warblers.
- a longer tail with white outer feathers, visible in flight and when flicked.
Conservation Status
From a conservation perspective, the Fan-tailed Warbler is currently considered to be of Least Concern with stable, widely but thinly distributed populations.