Some intense blue colors, including cobalt blue and cerulean blue, are made with cobalt compounds. Rear like blue dolphins their cerulean curves? The wings and tail are black with cerulean blue edges. See also painted swatch and crystals of cerulean blue at ColourLex. Cobalt stannate is a tin compound which is used as a cerulean blue pigment. The cerulean warbler is the fastest declining neotropical migrant songbird. It consisted of dark cerulean, icterine yellow, and isabelline gray. During the breeding season, the adult male appears mostly a vibrant cerulean blue. Cerulean warblers depend on shade coffee plantations during the winter. "Cerulean blue" is the name of a pigment. Except for the cerulean kingfisher they all have some rufous in their plumage. There are more than 25 species of warblers, including the rare cerulean warbler. Overall, "Blue" came in first, with "Cerulean" second and "Purple Heart" third. This bright tone of cerulean is the colour called "cerulean" by Crayola crayons.