Yellow Tyrannulet

How to find it

Check shrubby second growth, bamboo stands and field edges. It is easy to overlook because it is small and quick, so listen for the chattery song and then watch low exposed perches. Look for pairs, since it is usually seen with a mate or family group. Open fields and forest edges worked for one tour at La Selva, where a pair was working through grasses along the Police Station Road. Wet fields and scrubby field habitat on the southern Pacific side have also produced it, and so has a short walk at Virgen del Socorro, a brief stop along the road down from Cinchona.

How to recognise it

Look for a very small flycatcher with these marks:

Bright yellow underparts.

A bright yellow eyebrow.

A dark line through the eye.

A somewhat bushy crest.

Two wide but faint wing bars.

Olive green upperparts.

Its slender build and thin bill make it look like a tiny vireo or warbler. Males and females look alike, while young birds are browner above and paler yellow below.

It often perches horizontally with the tail partly raised, and sits more upright when resting. That posture helps you pick it out among the foliage.

What it sounds like

Recording: Pablo H Capovilla, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

This is an active, restless bird that flicks its tail. It makes short sallies to catch insects in the air and often returns to low, exposed perches, which can give good views. It is usually seen in pairs or family groups.

It apparently breeds nearly year-round in Costa Rica. The only fully described nests came from here: open cups of plant fibres, grass and bark, usually with moss on the outside.

Where it lives

It lives in shrubby second growth with some trees, and is sometimes found near stands of tall bamboo. It also uses thickets, forest and stream edges, dense second growth, and bushy pastures or clearings. It has a special liking for bamboo and avoids tall forest, preferring openings and edges with dense low vegetation.

In Costa Rica it reaches about 600 m on the Caribbean slope and about 1,200 m on the Pacific slope. The Costa Rican form occurs on the Caribbean slope, and on the Pacific slope from San José and central Puntarenas provinces southward into Panama.

Similar birds

It is a brighter yellow than most other tyrannulets, which helps separate it from them. Small yellow tyrannulets can still be hard to separate by ear. A tour group in the far north could not tell a calling Ornithion tyrannulet (Yellow-bellied or Brown-capped) apart west of Caño Negro, so learn the voices before you go.

Names and lore in Costa Rica

Costa Ricans call it Mosquerito Amarillo. Other Spanish-speaking countries use different names, such as tiranuelo amarillo in Colombia and mosquitero amarillo in Nicaragua.

Status and conservation

Listed as a resident (R) on the AOCR list, it is considered common in Costa Rica and is rated Least Concern worldwide.

Photography tips

Between flights after insects it often sits on low, open perches, so watch those and wait. Listen for the chattery song to locate it first, since it moves fast. Its horizontal posture with the tail partly raised helps you pick it out among the foliage.