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.

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. They are known in Mexico as chipe de roca.

The Fan-tailed Warbler is a mid-sized warbler. The sexes are similar in appearance. Their upperparts are grayishs, their forehead is black with a yellow crown patch, a white loral spot and narrow white eye crescents. Their lores are white and their underparts are yellow that transition to white ventrally. Their tail is long and graduated with a white tip. Their bills are long and black, their iris is dark, and their legs are dusky pink. They are found in submontane and lower montane evergreen and in 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 structurally similar to the Yellow-breasted Chat, Icteria virens.

The Fan-tailed Warbler is found in northern Mexican 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.

From a conservation perspective the Fan-tailed Warbler is currently considered to be of Least Concern with stable, widely but thinly distributed populations.