Sand martin

This species was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, and originally named Hirundo riparia; the description consisted of the simple "H[irundo] cinerea, gula abdomineque albis" ("an ash-grey swallow, with white throat and belly") and the type locality was simply given as "Europa", The specific name means "of the riverbank"; it is derived from the Latin ripa "riverbank". There are three or four weakly defined subspecies: • R. r. riparia (syn. R. r. dolgushini, R. r. innominata, R. r. kolymensis). Breeds Europe, western Asia, North America; winters Africa, South America. • R. r. taczanowskii. Doubtfully distinct from R. r. ijimae and often included in it. It is smaller, and has paler grey-brown upperparts and a less distinct breast band. It winters in Pakistan, southern India and Sri Lanka. ==Description==

The sand martin is brown above, white below with a narrow brown band on the breast; the bill is black, the legs brown. The young have rufous tips to the coverts and margins to the secondaries. Its brown back and breast band, white throat, small size and quick jerky flight separate it from similar swallows, such as the common house martin (Delichon urbicum), the American cliff swallow (Petrochelidon pyrrhonota) and the tree swallow (Tachycineta bicolor). The other species of Riparia are more similar; the sand martin generally only occurs them in the wintering range, though there is breeding range overlap with pale martin in central Asia, with both species sharing mixed colonies without interbreeding. The banded martin (Neophedina cincta) of sub-Saharan Africa is very similar in plumage pattern, but is markedly larger, nearly double the weight. Measurements: • Length: • Wingspan: • Weight: (to before migration) The song is a continuous gravelly twittering when the birds are on the wing and becomes a conversational undertone after they have settled in the roost. The harsh alarm is heard when a passing falcon, crow or other suspected predator requires combined action to drive it away. ==Ecology==

Linnaeus already remarked on this species' breeding habits: Habitat in Europae collibus arenosis abruptis, foramine serpentino ("it lives in Europe, in winding holes in sheer sandy hills"). It has been observed that sand martins favour loess as a particular type of ground to nest in. Sand martins are generally found near larger bodies of water, such as rivers, lakes or even the ocean, throughout the year. by the IUCN. They are considered threatened in California, where populations exist in the Sacramento Valley and at two coastal sites, Año Nuevo State Park and Fort Funston. ==Gallery==

File:Digesvale.jpg|Showing dark breast band File:Riparia Riparia-2006-Ejdzej-1.jpg|Adult at nest site, Dziwnówek, Poland File:Sand-Martin.jpg|Active breeding colony File:Backsvala - (Riparia riparia) - Nest - Ystad-2021.jpg|Abandoned breeding colony File:Riparia riparia-nest.jpg|Nest with egg File:Riparia riparia MWNH 2218.JPG|Eggs, Collection Museum Wiesbaden, Germany ==References==