Juan Manuel Borrero / Illustration of Hirundinidae family: Common Sand Martin (Riparia riparia), Northen House-Martin (Delichon urbicum), Common Swift (Apus apus) and Barn Swallow (Hirundo rustica). Pencil and watercolor p...

Markus Varesvuo / Sand martins (Riparia riparia), Barn swallows (Hirundo rustica) and Yellow wagtails (Motacilla flava) collecting mud for nests on ground, Israel, May