Sulphur-rumped Flycatcher

How to find it

Start by looking for mixed flocks in the lower levels of the forest, because this flycatcher is named among the birds that join them, along with antvireos and antwrens. At Carara, tour groups have spotted it coming to the stream bathing pools used by manakins, and another group found one perched high above that stream, so streams are worth your time. Watching ant swarms may also help, since one bird visited a swarm. Listen for the sharp, dry call. When you find a perched bird, watch for the fanned tail and drooping wings.

How to recognise it

This is a small flycatcher, about 12 cm long. Learn it by these marks:

Head and upper back: olive-brown.

Wings and tail: blackish.

Breast: tawny.

Face and eye ring: grey.

Throat: whitish.

Belly: yellow, and so is a small crest.

The pale yellow rump patch that names the bird reaches up to the mid-back. It often shows it off by fanning its tail and drooping its wings, which is a useful clue when you see it perched.

What it sounds like

Recording: rawcomposition, CC0 1.0, source, read 4 Nov 2026.

Behaviour and diet

It forages very actively, hopping energetically from branch to branch and chasing flying insects in the air. It joins mixed-species flocks that move through the lower levels of the forest, and it is often found near streams.

At Carara National Park one bird was photographed feeding alone in the dark mid-level of the forest, with a mixed flock, at about 452 m elevation. On the Caribbean slope a bird was seen perched low in brush at La Selva. Another was seen visiting an ant swarm, with its yellow rump showing clearly.

Where it lives

Its natural habitat is tropical and subtropical moist lowland forest. In Costa Rica it has been recorded on both slopes: on the Caribbean side at La Selva, in the Arenal area, at La Fortuna and in Guatuso in the northern lowlands, and in the Turrialba area, where it is listed as a resident.

On the Pacific side it occurs at Carara National Park in Puntarenas, at Corcovado National Park (La Sirena sector) on the Osa Peninsula, and in the southern Pacific foothills around Mastatal. The Carara bird at about 452 m elevation shows it reaches into the foothills.

Similar birds

The Black-tailed Flycatcher (Mosquerito Colinegro) is the only other Myiobius in Costa Rica, and it looks very much like this bird, with an olive back and yellow rump. One source says its chest and upper belly are usually paler and more uniform in colour. Its call is a softer, thin note, weaker than the Sulphur-rumped's, which may help you separate the two by ear. On one national checklist it is the rarer of the two.

Names and lore in Costa Rica

Other Spanish names used for the species include atrapamoscas de rabadilla amarilla, mosquero rabadilla amarilla and mosquitero rabiamarillo. The name used for Costa Rica is Mosquerito Lomiamarillo.

Status and conservation

The official Costa Rican list gives it resident status, and the IUCN rates the species Least Concern.

Photography tips

At Carara, one bird was found foraging in the dark middle level of the forest with a mixed flock. Low light there means you should look for flock activity rather than open perches.