Mishná sur Le Lévitique 1:18

A bird hatat is performed below [the red line], but a beast hatat is performed above [the red line]. A bird olah is performed above, but a beast olah below. If he changed this procedure with either, then the offering is disqualified. The seder [ordered ritual] in the case of kinnim is as follows: In the case of obligatory offerings, one [bird] is a hatat and one an olah. In the case of vows and freewill offerings, however, all are olot. What constitutes a vow? When one says: "It is incumbent upon me to bring an olah." And what constitutes a freewill-offering? When one says: "Behold, this shall be an olah." What is the [practical] difference between vows and freewill offerings? In the case of vows, if they die or are stolen, one is responsible for their replacement; But in the case of freewill offerings, if they die or are stolen, one is not responsible for their replacement.

Thirteen rulings govern the carrion of a clean bird:There must be intention; It need not be rendered susceptible; It conveys food uncleanness if its minimum bulk is that of an egg; And it conveys uncleanness when in one's gullet if its minimum bulk is that of an olive; He that eats of it must wait until sunset [to be clean]; Guilt is incurred on account of it for entering the sanctuary; Terumah is burned on account of it; He who eats a limb of it while it is alive suffers forty lashes; Slaughtering it or nipping [off its neck] cleanses it even if it is terefah, the words of Rabbi Meir. Rabbi Judah says: they do not cleanse it. Rabbi Yose says: the slaughtering does cleanse it but nipping does not.