Tree Swallow Identification Guide

Key Field Marks

• Size & shape: A small, compact swallow with fairly broad-based, pointed wings and a short, only shallowly notched tail (not deeply forked like Barn Swallow).
• Plumage: Adults show glossy blue-green (can look almost teal or bottle-green in different light) upperparts contrasting sharply with immaculate white underparts, including a clean white face and throat with no dark mask.
• Sexes: Males are brighter, more uniformly iridescent blue-green; females and first-year birds are duller, browner above, sometimes with a faint breast band suggestion, but always white below.
• Behavior: Highly aerial, feeding on flying insects with quick, buoyant wingbeats and long glides low over water, fields, and marshes. Often seen in large flocks, especially during migration, swirling over wetlands or gathering by the thousands on wires in late summer/fall.
• Nesting: A secondary cavity nester, using old woodpecker holes and readily taking to nest boxes — often seen carrying white feathers, which it uses to line the nest.

Separating Tree Swallow from Similar Species

• Violet-green Swallow (western species): Shows white patches on the face that extend above and around the eye and onto the rump sides (visible as white flank patches nearly meeting over the rump), whereas Tree Swallow has a solid dark cap down to the eye and no white rump patches.
• Barn Swallow: Has a deeply forked "swallow tail," rusty-buff underparts and throat, and a dark chestnut forehead/throat — very different from Tree Swallow's clean white underparts and shallow tail notch.
• Bank Swallow / Northern Rough-winged Swallow: Both are brown above (not iridescent blue-green) with a distinct brown breast band (Bank Swallow) or dingy brown throat wash (Rough-winged) — Tree Swallow never shows brown upperparts or a breast band.
• Female/juvenile Tree Swallow vs. Rough-winged Swallow: Can look superficially similar (dull brown-ish above), but Tree Swallow retains a clean white underside without the smudgy brown throat wash of Rough-winged.

Where & When to See It

Breeds widely across Canada and the northern-to-mid United States, especially near open water, wetlands, and fields with nearby dead trees or nest boxes. Highly migratory; one of the earliest swallows to return in spring and among the latest to depart in fall because it can subsist on berries (notably wax myrtle/bayberry) when insects are scarce, allowing it to winter farther north than other swallows — from the southern U.S. and Mexico south to Central America.

Voice

Gives a liquid, cheerful chattering song and calls of bright, twittering "chi-veet" or "silip" notes, often delivered in a cascading series from a perch or in flight; flocks produce a constant twittering chorus, especially around nest boxes and staging areas.