Slaty Antwren

How to find it

Start by finding a mixed flock, because the antwren is usually part of one. Listen for the thin 'cheeur' call, then scan the low and mid levels of the understory. It usually forages in dense vegetation about 1 to 6 m up, but sometimes on the ground or as high as 12 m. A guided group heard one across a valley and then found a few in a mixed flock along the Tapantí park road. At Curi-Cancha Reserve near Monteverde, flocks can include Slaty Antwren alongside Plain Antvireo, Spotted Barbtail and Eye-ringed Flatbill. Check ant swarms where you meet them, as birds there can appear one after another.

How to recognise it

This is a very small antwren, about 10 cm long and weighing around 9.5 g. The English name refers to its slate color, and the scientific name means 'small ant hunter' of slate color.

The white on the wings is less extensive than on related antwrens, which helps separate the male from similar species.

It is so small that it is easy to overlook among bigger birds, so size, slate tone and the company it keeps are the most useful clues. Look for pairs or small family groups moving through the understory rather than a lone bird in the open.

What it sounds like

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

Behaviour and diet

Look for it with mixed-species flocks rather than alone. It usually forages in pairs and often tags along with woodcreepers, ant-tanagers, ovenbirds and Basileuterus warblers.

It picks insects and spiders off leaves and gleans from dead leaf clusters and vine tangles. When prey is dislodged, it chases it to the ground.

Birders in the Monteverde area found it with an ant swarm, where a quiet, stealthy flock attended the swarm and the birds appeared one after another.

The nest is a deep cup of fine fungal threads bound with spider silk, hung from a branch fork, usually less than about 2 m above the ground.

Where it lives

It lives in the understory of wet foothill and cloud forest and in nearby tall second growth. In Costa Rica it reaches about 2,000 m, while across Central America it generally ranges from sea level to about 1,250 m. It tends to live higher than most other antwrens.

In Costa Rica and Panama it is found in semi-humid forest on the Pacific slope. Records come from Tapantí National Park in Cartago, the Monteverde area, Arenal, Carara and the deep south near San Vito.

When to see it

In Costa Rica it breeds between March and July.

Similar birds

The male is separated from similar antwrens by its wings, which show less white than related species. Because it is so small and moves with other birds, take a careful look at the wing before settling on the name.

Names and lore in Costa Rica

In Costa Rica the usual Spanish name is hormiguerito pizarroso, the same as in Colombia, Honduras and Peru. Mexico and Venezuela use hormiguerito or hormiguero apizarrado, and Nicaragua uses hormiguerito pechinegro. Hormiguero Plomizo is also listed for this species.

Status and conservation

The AOCR list marks it as a resident (R), and the IUCN rates it Least Concern, with a very large range and uncommon to fairly common numbers.

Photography tips

Scan the low and mid levels of the understory, where it forages in dense vegetation about 1 to 6 m up. A blogger on a Costa Rica trip found it hard to photograph, as few photos of the bird exist, so patience with a passing flock matters.