Tree Swallow

How to find it

Look for open ground near water, where flocks hunt. Scan the larger flocks of other migrant swallows, because a few Tree Swallows are often tucked among them. This happens both on autumn passage and in winter. Check for white undertail coverts and a deeper tail notch to pick them out. Sometimes they form large single-species flocks, so keep an eye out for that. Expect numbers to change from one year to the next.

How to recognise it

Field marks to look for:

The adult male is glossy dark blue-green above, with blackish wings and tail. Below it is pure white, sometimes with a grayish tint on the breast. The tail is notched, and the undertail coverts are white. It is a small swallow, about 14 cm long.

Juveniles look different. They are grayish brown above, with a dusky band across the chest. Their underparts are clearer white than those of young Bank or Northern Rough-winged Swallows, a useful clue when a mixed flock sweeps past.

What it sounds like

Recording: Mason Holum, CC BY 4.0, source, read 4 Nov 2026.

Behaviour and diet

The Tree Swallow catches insects in flight. It forages up to about 50 m above the ground, alone or in groups, and its flight mixes flapping and gliding. It glides more than other swallows.

Just before sunset, flocks can gather in dense swirling clouds over a roost site, then drop down to perch. In Costa Rica, a few Tree Swallows are often tucked among larger flocks of other migrant swallows, though sometimes they form large single-species flocks.

Where it lives

In Costa Rica it ranges from the lowlands of both slopes up to about 1500 m. It is a migrant and winter resident.

It frequents pastures and open savanna near ponds, marshes or salt pans, and sometimes flies over open water.

When to see it

It is a passage migrant from early September to late October and again in March and April. It is also a winter resident.

Similar birds

It is larger than the Blue-and-white Swallow, with longer wings and tail, a deeper tail notch and white undertail coverts. Juveniles resemble Bank Swallows, but the Bank Swallow is smaller, with a crisp, clean-edged brown breast band, white behind the ear and a paler brown rump. Violet-green Swallow is a rare migrant in Costa Rica; its white reaches above and behind the eye and it has white patches on the rump sides, while the Tree Swallow's white does not reach above the eye.

Names and lore in Costa Rica

The official Spanish name on the Costa Rican list is Golondrina Bicolor. Plain 'golondrina' is also used as a common name.

Status and conservation

The AOCR lists it as a migrant (M), and the species is rated Least Concern.

Photography tips

Look for open ground near water, where flocks hunt. Birds forage up to about 50 m above the ground, so a flock hunting low over a pond gives the best chance of a clear view.