Birds mate by rubbing their cloaca together in what scientists call a cloacal kiss. Birds of both sexes have a cloaca, which is an opening that swells and sticks out of the body slightly during mating season.
After an elaborate wooing and courtship process that may include auditory calls, songs and even dances, copulation lasts generally for just a few seconds with the female hunching to help the male balance and moving her tail to the side to expose her cloaca so that it can touch his. It is during this rubbing session that the male sperm is deposited into the female cloaca. The sperm makes its way to the bird's ova where fertilization occurs. The eggs can be laid a few days later or even several months later, depending on the particular type of bird.