Black-fronted Tyrannulet

Fairly common within humid montane tepui forest but inconspicuous and the song is infrequently heard, so it is genuinely tricky to find; access to the remote tepui belt is the main limiter. A 'work-for-it' endemic.

Distinctive for a Phylloscartes (~12–13 cm, 8–11 g): obviously gray crown, black forehead and lores plus a grizzled black-and-white face giving a 'frowning' look, and largely very pale underparts that lack any yellow wash — unusual for the genus. The clean, yellow-less underparts plus the black-fronted frowning face are the key marks.

Interior and edges of humid montane evergreen forest, and to a lesser extent mature secondary forest dominated by Melastomataceae; roughly 800–1800 m.

Active, restless mid-story flycatcher; usually in pairs and a regular member of mixed-species flocks, gleaning insects from foliage with quick acrobatic moves (often cocks/holds the tail). Suspected to also take small fruits.

Infrequently heard song a long (2–3 sec) very thin trill, the last half slightly descending; foraging call a thin sharp 'tsuk-cheez-tr'r'r'r'r'r...' (2nd note highest), also a 'cheh-cheh-ch'leet!'. Learn these well — voice is the main way to detect it. Search Xeno-canto and Macaulay Library for 'Black-fronted Tyrannulet' (eBird/ML code blftyr1).

Pull it out of mixed-species flocks on the upper Escalera and rely on the thin descending trill rather than expecting frequent song. Teach trainees the 'no yellow below + black frowning face' combo to nail it against the other small flock tyrannulets — it is the kind of subtle endemic that impresses serious listers.