Zevachim 6:3

Anyone who ascended the altar did so on the right, going around and descending on the left, except for those who ascended for the three things enumerated at the end of the previous mishna (i.e., water libations, wine libations and bird burnt offerings). These people ascended the altar and then turned around on their heels (going back the way they came).

Zevachim 6:4

Sin offerings of birds were prepared as follows: the kohein nipped the head of the bird at the nape without severing it and sprinkled its blood on the wall of the altar. He drained the rest of the blood over the base of the altar. The altar only received the blood of this sacrifice; the rest of the bird went to the kohanim.