Hilchos Maasei Hakarbanos 6:20

A bird burnt offering was brought as follows: The kohein ascended the ramp. He turned right on the ledge and proceeded to the southeast corner, where he would separate the bird’s head at the nape of its neck. If he does not separate it completely, the offering is unfit. He squeezes the blood of the head and the blood of the body onto the wall of the altar above the dividing line in the middle. If he squeezed out the blood of the head but not of the body, it is invalid; if he squeezed out the blood of the body but not of the head, it is valid.

Hilchos Maasei Hakarbanos 6:21

The kohein takes the head and brings the place where it was severed to the altar; he dips it in salt and throws it on the fire. He then comes to the body. He manually removes the crop, and the skin that is on it with the feathers. He takes the intestines that come out with it and throws them on the ash heap.