Audubon Aquatint, Carbonated Warbler

AUDUBON, John James (1785 - 1851).
Carbonated Warbler, Plate 60.
Aquatint engraving with original hand color.
London: Robert Havell, 1827-1838.
38 5/8" x 25 1/2" sheet.
Comparable: Christie's, 1/18/2001 - $1,998; Christie's, 9/14/1987 - $1,540
They were both busily engaged in searching for insects along the branches and amongst the leaves of a Dog-wood tree. Their motions were those common to all the species of the genus Sylvia. On examination, they were found to be both males. I am of opinion, that they were both young birds of the preceding year, and not in full plumage, as they had no part of their dress seemingly complete, excepting the head.