Me'ilah 8 - The Progression Of Bird Sin-Offering
A bird sin-offering is either a turtledove or a young pigeon. As soon as one verbally consecrates it as such, it becomes completely forbidden for any other use, and thus the laws of misappropriation begin. After it is slaughtered, and its blood is applied to the Altar, no parts of it are burned on the Altar, but edible parts are eaten by the Kohanim. Naturally, since its meat is permitted to the Kohanim, the laws of misappropriation cease to apply.
The slaughter of birds is done completely differently than that of animals: the bird's neck is pierced with a thumbnail from the back of the neck. This process is called " melikah ." After the melikah is done, the bird becomes susceptible to be disqualified, such as if it comes in contact with someone who went to the mikvah to purify himself, but the sun did not set it; or with one who needs an atonement offering but has not brought it yet; or it was left beyond permitted time. Its last service is sprinkling of its blood on the Altar. At this time, the wrong intention disqualifies it. If the intentions were right, but one ate it beyond its time or while being impure, becomes liable to being cut off from his spiritual source.
Art: Porfiri Egorovich Pilaev - Feeding The Pigeons