Leviticus 1:14-16

14And if the burnt sacrifice for his offering to Yhwh be of fowls, then he shall bring his offering of turtledoves, or of young pigeons. 15And the priest shall bring it unto the altar, and wring off his head, and burn it on the altar; and the blood thereof shall be wrung out at the side of the altar:1 16And he shall pluck away his crop with his feathers, and cast it beside the altar on the east part, by the place of the ashes:2