Pigeons

"Pigeons" (clade Columbidae) constitute a wide variety of common bird found in almost every region and ecostystem of the world. Also known as "doves" (from a Germanic word descriptive of their diving flight), pigeons can range in size from that of a turkey (Crowned Pigeon of New Guinea) to that of a small house sparrow (New-world Ground Dove). Usually typified by short beaks and legs with a small head on a larger compact body, pigeons articulate their characteristic head-bob as a means of keeping their visual field consistent as they walk. With an enormous ratio of wing-muscle mass to body weight (nearly 41%), pigeons are one of the strongest fliers of any winged species and are highly maneuverable in flight. Across the field of expressions, pigeons display a wide variety of colors and patterns, ranging from brightly colored with ornamentation and plumage to dull and neutral with little flash. Of the three hundred and ten known species, fifty-nine are threatened with extinction.
Pigeons and doves have a unique place in religious literature. In the Hebrew Bible pigeons are acceptable sacrifices, the chosen bird to seek land during the Great Flood, as sign of endearment (Song of Songs), and, most importantly, the form the Holy Spirit takes in descending upon Christ after his baptism. In Islam, pigeons are held as sacred through the belief that they aided Muhammad in defending the cave of Thaw'r from his enemies.
"Pigeon" or "pigeons" appear in seven Stevens' poems: "Like Decorations in a Nigger Cemetary," "Sunday Morning," "Gray Stones and Gray Pigeons," "Examinations if the Hero in a Time of War," "Notes Toward a Supreme Fiction," "L'essor Sacade," and "Le Monocle de Mon Oncle." In general Stevens deploys the pigeon against its religious associations, emphasizing instead their commonness, dullness, and excrement (i.e. "a marble soiled by pigeons" in "Examinations"). Most famously Stevens deflates their Christocentric symbolism in "Sunday Morning," in which the final image of this poem about a turning away from Christianity reads:
 And, in the isolation of the sky,
 At evening, casual flocks of pigeons make
 Ambiguous undulations as they sink,
 Downward to darkness, on extended wings.