Pigeons lack external sex organs, and like many birds, they utilize a cloaca to reproduce rather than dedicated organs such as a penis or vagina. They also do not differ in plumage depending on sex, as many other birds do. This makes determining sex difficult.
Males are slightly larger than females, beginning at birth. The crown of their heads is set somewhat higher. However, most clues to proper pigeon sexing are behavioral. Males are more aggressive than females. When courting, males drag their tail feathers and chase after their intended mate, puffing out their chest and strutting in a circle. Females "beak," placing their beak into the opened mouth of their partner. Females also stroke the back of the male's neck when they desire to mate.