Bay-breasted Warbler

How to find it

Aim for fall passage, when the Caribbean lowlands and foothills hold the most birds. Check canopy flocks at forest edges, since in tropical wintering areas it often joins mixed-species flocks and feeds high up. Because the song is so quiet and hard to pinpoint, watch for moving foliage and the buzzy sip call rather than waiting for a song. In the Central Valley, trees in urban parks are worth a look: one Costa Rican naturalist searched freshly pruned trees in a park during a year when many more than usual passed through. On trips we build, guests can meet it in the Central Valley on fall passage, including in parks with trees.

How to recognise it

Winter birds are olive with black streaks above. They usually show some chestnut on the crown and a whitish throat. Look for these marks:

A strong chestnut tint on the flanks.

Two white wing bars.

Buff undertail coverts.

In fall plumage the face and underparts look pale lemon, with a little pink on the flanks, and the crown and back are olive with dark streaks. Fall females and immatures show little bay colour, so look for a plain face without a strong eyeline, a bright yellow-green head and back, and bold white wing bars.

The breeding male, which is how the species looks on its breeding grounds, has a black face, chestnut crown, throat and flanks, a pale neck patch and two white wing bars.

What it sounds like

Recording: Mary E. Macaulay, P.Eng., CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

In Costa Rica in winter it is usually solitary and often joins mixed flocks with other warblers. In the migration season it moves in flocks and waves.

It searches foliage and twigs, looks around, then hops or flutters after prey. It mostly eats slow-moving insects, including many larvae. While perched it is quick to flick its tail, which helps pick it out among the leaves.

Where it lives

In Costa Rica in winter it prefers forest edges and partly cleared areas, and is sometimes in the forest canopy or in secondary growth. In fall it can turn up almost anywhere, from forest interior to pastures.

Fall migrants become less numerous at higher elevations but regularly reach at least 1850 m and cross the Central Valley. They are rare in the Pacific lowlands. As winter residents they are uncommon to rare but regular in the lowlands, and in places they reach 1200 m on both slopes.

When to see it

In fall it passes through from late September to mid-November. In spring it passes mainly along the Caribbean coast, from April to early May, and some birds are still around in midwinter in non-breeding plumage.

Similar birds

Fall Blackpoll Warblers look very similar. Blackpolls have white undertail coverts and often yellowish feet, while the Bay-breasted has buff undertail coverts and always dark legs. It also lacks blurry chest streaking. The song is easy to confuse with those of Blackpoll and Cape May Warblers; it is similar in tone and pattern to Cape May but softer.

Names and lore in Costa Rica

Costa Rica uses Reinita Castaña. Other Spanish names are used elsewhere, such as chipe pechicastaño in Mexico and reinita pechicastaña in Panama.

Status and conservation

The official Costa Rican list marks it M, a migratory species that breeds elsewhere and does not nest here.

Photography tips

The tail flick while perched helps pick it out among foliage. Check canopy flocks at forest edges and watch twigs patiently, since it searches foliage and then hops or flutters after prey.