Chestnut-backed Antbird

How to find it

Start by listening, because it is easier to hear than to see in dense forest. Birders can draw it into view by imitating its whistled song, and it may then show a puffed-up body, drooped wings and a pumping tail. Scan low along forest edges, streams and old treefall gaps. At Carara, a guide on the main loop trail saw it well near an army ant swarm and calls it commonly seen there. Finding a swarm is called the most reliable way to see antbirds.

How to recognise it

Think small, chunky and short-tailed. The bird is about 14 to 15 cm long and weighs roughly 29 g.

Look for a bold eye ring and spots on the wing. Costa Rican experts used exactly these marks, together with the habit of living in pairs, to identify the bird on a decorated artifact from an archaeological project.

The two Costa Rican forms differ in colour below. The Caribbean form has darker chestnut underparts. On the Pacific slope the female of the form occidentalis has more rufous underparts.

When excited, it may show a puffed-up body, drooped wings and a pumping tail. Use the eye ring, the wing spots and the compact shape together rather than leaning on one mark.

What it sounds like

Recording: Dan MacNeal, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

This antbird feeds low in the vegetation, sometimes with other species in mixed flocks. It is usually alone, in pairs or in family groups, and pairs stay together through the year. In northeastern Costa Rica a territory is roughly 1 to 3 hectares.

In a territory dispute, birds pound the tail, sleek the back of the head and sing hard, and both sexes do this.

It is not an obligate army ant follower. It joins a swarm only when one passes through its territory, so a swarm is a good chance to see it.

Where it lives

It lives in the understory of wet forest, especially at edges, along streams and in old treefall gaps. In Costa Rica it occurs up to about 1,200 m elevation.

The nominate form lives on the Caribbean slope. The subspecies occidentalis lives on the Pacific slope of western Costa Rica. Its song has also been recorded in the Gandoca-Manzanillo and Sixaola area of the Caribbean southeast.

When to see it

Breeding has been recorded between April and November in Costa Rica and Panama.

Similar birds

Dusky Antbird is another antbird seen with it at Carara. Dusky Antbird favors second growth at the park edge, while Chestnut-backed stays in the forest understory.

Names and lore in Costa Rica

Costa Ricans use the AOCR name Hormiguero Dorsicastaño. Other Spanish names are hormiguero de lomo castaño and hormiguerito dorsicastaño.

A Costa Rican museum identified this bird on a decorated artifact, and noted that the artifact's sound is very like the bird's song.

Status and conservation

The AOCR list marks it as R, a resident, and the IUCN rates it Least Concern, meaning no significant threats to survival.

Photography tips

An army ant swarm is the best chance for a clear view, since the bird joins swarms that pass through its territory. A Costa Rica trip account lists it among the birds that visit swarms. Imitating its whistled song can bring it into the open, and at Carara birds have perched on the path.