Bringing a bird as a sin offering involves a highly unique procedure for handling its blood, distinctly different from other sacrifices. The primary approach among commentators is that instead of collecting the blood in a vessel and applying it with a finger or a branch, the sprinkling is done directly from the bird's body. The priest holds the back of the bird's neck or its body, moves it forcefully up and down, and splashes the blood from a distance toward the altar [רש"י, רשב"ם, מלבי"ם, ביאור יש"ר, רד"צ הופמן]. This action separates the bird sin offering from the bird burnt offering, which involves no sprinkling at all, only the squeezing of blood [רש"י, רשב"ם]. Additionally, this specific service is valid only when performed by priests and is invalid if done by non-priests or women [תורה תמימה].
The precise target for the blood is the wall of the altar, rather than the ramp or the entrance to the sanctuary [תורה תמימה]. The sprinkling must occur on the lower half of the altar, specifically below the red line that surrounds it, at the southwestern corner [רד"צ הופמן, רלב"ג, תורה תמימה]. This requirement ensures that the blood naturally flows and drains down toward the foundation, which is the lowest level of the altar. Such a natural downward flow is only possible when the initial sprinkling is directed at the lower wall [מלבי"ם, תורה תמימה, מנחת שי].
Because it is impossible to extract all the blood through splashing alone, the remaining blood must be actively drained [ביאור יש"ר]. At this stage, the priest presses the cut in the bird's neck directly against the wall of the altar. He squeezes the remaining blood between his fingers so that it runs down to the foundation [חזקוני, פרדס יוסף, מלבי"ם].
The entire procedure must be accompanied by a specific mindset regarding the offering's status. The primary approach among commentators is that the service must be performed explicitly for the sake of a sin offering, and it becomes invalid if done with another sacrifice in mind [רש"י, אדרת אליהו, מלבי"ם]. Although this rule is already established for animal sacrifices, it is reinforced here because the procedure for a bird sin offering is so radically different that one might mistakenly assume its core laws are also different [מזרחי, שפתי חכמים, גור אריה]. The underlying essence of the sacrifice remains paramount [ברכת אשר]. Ultimately, the required squeezing of the blood is an absolute condition that determines the validity of the offering, not merely an optional step [תורה תמימה]. Furthermore, the meat of the bird sin offering is legally equated to that of an animal sin offering, meaning it is to be eaten by the priests [ביאור יש"ר, רד"צ הופמן].