a pair of cliff swallows petrochelidon pyrrhonota building a nest on a wooden ledge, in the spring time, san francisco bay area

america american animal animals area bay beak bird birds brown building california cliff colorful copy couple cute detail environment environmental face feather francisco free head ledge ledges life living mud muddy natural nature nest ornithology outdoors outside pair petrochelidon plumage pyrrhonota san small song songbird space spring states swallow swallows time tiny two united usa watching wild wildlife wooden