Basileuterus lachrymosus
Silhouette: Andy Wilson · PhyloPic
In 3 days ~50% in a week ~80%
The fan-tailed warbler (Basileuterus lachrymosus) is a species of bird in the family Parulidae, the New World warblers. It is found from Mexico to Nicaragua. It has also been recorded as a vagrant in the U. S. states of Arizona, New Mexico, and Texas. Its "habit of constant tail-fanning and tail-swinging [is] distinctive".
The fan-tailed warbler has a complicated taxonomic history that as of July 2026 has not been resolved. Its formally description in 1850 with the binomial Sylvia lachrymosus is credited to Charles Lucien Bonaparte. However, Bonaparte appended "(Basileuterus? lachrymosus, Cabanis)" to the binomial. Cabanis had not published the name and so is not credited with the description despite the species' later assignment to his genus. In 1850 Cabanis had also erected genus Euthlypis, and in 1902 Robert Ridgway assigned the fan-tailed warbler to it, retroactively declaring it the type species of the genus.
A molecular phylogenetic study published in 2010 found that the fan-tailed warbler was basal to the genus Basileuterus. Based on the study, in 2011 taxonomic systems began reassigning it to that genus. As of July 2026 the IOC, BirdLife International... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Cañón del Sumidero National Park | 🇲🇽 Mexico | |
| 2 | El Triunfo | 🇲🇽 Mexico |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | San Salvador | 🇸🇻 El Salvador |
Possible
About 20% of wildlife watchers report a Fan-tailed Warbler sighting in El Triunfo on a given day, based on 39 verified sightings from GBIF citizen-science data from 2019 to 2026. It is the 86th most-seen of the 221 birds we can rate there. Over three days the chance rises to about 50%, and over a week to about 80%, if each day is a fresh chance.
April
In that month about 50% of wildlife watchers report a Fan-tailed Warbler in El Triunfo on a given day, against about 10% in March, May and July–January, the lowest months. That is one of El Triunfo's driest months, with about 65 mm of rain against 420 mm in June. June has too few records to rate.
Between 8 and 11 am
Across all the parks we cover, that three-hour window holds the most Fan-tailed Warbler sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 2 parks where we can rate Fan-tailed Warbler sightings, El Triunfo ranks 2nd at about 20%, level with the leaders once rounded. The best odds are in Cañón del Sumidero National Park (Mexico, about 20%).
Same genus: Basileuterus
The closest relatives of the Fan-tailed Warbler that you can see in El Triunfo (genus Basileuterus) are Rufous-capped Warbler (about 50%), Golden-crowned Warbler (about 30%) and Golden-browed Warbler (about 20%), with each one's daily chance of a sighting.
GBIF citizen-science records
It is estimated from how often the Fan-tailed Warbler is recorded against all the birds logged in El Triunfo (39 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
