Grass Wren

How to find it

Head for the wet, tall-grass fields around Coris and scan the tops of grass clumps and bushes for a small bird on an open perch. In the breeding season the male perches in the open and sings, which gives away where it is. The rest of the time it creeps low through tall grass and is hard to watch. Imitated squeaking sounds can bring it up to scold. A birder at Coris found several in the first wet field his group scanned. Be patient and ready to look fast, because it dives back into cover quickly.

How to recognise it

Look for a tiny, slim wren, about 11 cm long, with a fairly long tail.

Adults show a black crown and back with thin pale buff streaks. The throat and belly are white. The breast is buffy. The back is streaked, and the rump is cinnamon.

The cinnamon rump shows in flight, a useful clue when the bird drops back into the grass. Juveniles are duller brown, with fainter streaking.

What it sounds like

Recording: Valentín Alfano, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

The Grass Wren is always alert, active and irritable. It probes through grass, leaves and twigs for small beetles and other insects.

It usually stays hidden, but it will sing or scold from an open perch on a grass clump or bush, then dives back into cover quickly.

The nest is a hollow ball of grass leaves with a low side entrance, set a few centimetres above ground in dense grass or rushes. It lays 4 white eggs.

Where it lives

In Costa Rica it lives in low, waterlogged meadows with tall grass, damp scrubby fields and open marshes. Near Cartago it uses wet, flooded fields, tall-grass pastures and scrub, and it is hard to see in these places.

Resident birds are in the Guarco area of Cartago, around Coris and Ochomogo. It sometimes wanders to San José and has also been recorded at San Vito and Cañas Gordas. No reports exist from other places in the country.

Across its whole range the species uses savannas, grasslands and wetlands, and in the Andes it reaches about 4000 m.

When to see it

Breeding runs from April to December.

Similar birds

Costa Rica has about two dozen wren species, but only this one is a small, streaked wren of open wet grass near Cartago. Its cinnamon rump shows in flight. The Costa Rican birds also look and sound a little different from northern Sedge Wrens.

Names and lore in Costa Rica

Costa Ricans call this bird Soterrey Sabanero, and also Guachipelín. Wrens in general are often called cucaracheros, meaning cockroach hunters.

Status and conservation

The AOCR list marks it as a resident (R), and it is listed as endangered in Costa Rica because the draining of wetlands has destroyed its habitat.

Photography tips

Watch the tops of grass clumps and bushes, where it will perch in the open to sing or scold, especially when it hears imitated squeaking sounds. It dives back into cover quickly, so keep the camera ready. A scope helps, since it tends to stay in the long grass.