Leviticus 1:14-16

14“‘If his offering to the Lord is a burnt offering from the birds, he must present his offering from the turtledoves or from the young pigeons.

15The priest must present it at the altar, pinch off its head and offer the head up in smoke on the altar, and its blood must be drained out against the side of the altar.

16Then the priest must remove its entrails by cutting off its tail feathers, and throw them to the east side of the altar into the place of fatty ashes,