Mangrove Swallow

Tachycineta albilinea

eBird gives this description for the Mangrove Swallow:  Small swallow of tropical lowlands. Usually near water, from mangroves and coastal lagoons to rivers well inland; mainly in small groups, often mixed with other species of swallows. In its range, the big white rump patch is distinctive. Adult is metallic blue above with small white chevron across base of bill; gleaming white below. Juvenile has dusky gray-brown upperparts with white rump, looks like adult by early winter.

The Birds of the World website introduces the Mangrove Swallow with this descriptive information:  The Mangrove Swallow (Tachycineta albilinea), is a relatively small swallow.  It is a common resident from Mexico to south Panama, predominantly along the coast, becoming rarer moving inland.  The Mangrove Swallow is associated with areas of water, including mangroves, but may be found near rivers, lakes, ponds, marshes, coastal beaches, and wet meadows.  It is an aerial insectivore, and outside of the breeding season it may forage in large groups.  During the breeding season they are socially monogamous and breeding pairs are highly territorial of their nests. These nests usually are located in crevices in partially submerged snags and logs.  The upperparts are dark, part from a white rump; in fresh plumage the color is nearly black with a green-blue gloss, but with wear the color becomes closer to steel-blue.  The underparts are white with a gray wash.  A characteristic feature that distinguishes the Mangrove Swallow from other white-rumped swallows is the white supraloral streak.

I saw and photographed my first Mangrove Swallow on the late afternoon of February 10, 2023, while on a boat tour of the Tarjole River in Costa Rica.  As we departed the dock, there were several of these swallows flying near the boats and dock.