Chullin, Chapter 12, Mishnah 3. This chapter is devoted to the mitzvah of shiluach haken, sending away the mother bird before taking the young. Having established in the earlier mishnayot which birds and which nests the mitzvah governs, our mishnah refines the picture from several angles: how close the mother must be to the nest, how many eggs or chicks are needed, which eggs and which chicks count at all, what happens when the mother keeps returning, and whether the finder may reverse the arrangement to suit himself.
When the Mother Is in the Air Above the Nest
"Haytah me'ofefet": when the person arrived at the nest to collect the eggs, the mother was aloft, hovering in the air over her young rather than settled inside. Does that count as her being present with them, or not?
The mishnah fixes the boundary at physical contact. "Bizman shekenafeha nog'ot baken": so long as her wings still reach down into the nest and touch what lies within, then "chayav leshale'ach," he must send her off, even though she has not lowered herself onto her young. But "ein kenafeha nog'ot baken": if her wings fall short and make contact with nothing, then "patur mishale'ach," no obligation rests upon him.
The measure comes from the language of the pasuk, which describes the mother as "rovetzet," roosting. Notice which words the Torah did not choose. It did not say "yoshevet," sitting, which would have required her to be fully settled on the nest. And it did not say "me'ofefet," hovering, which would have included a mother entirely detached from her young, floating above them in the air. "Rovetzet" describes something in between: she is over the eggs, rising and lowering herself, present in that space and in contact with them, without needing to be seated upon them.
How Many Eggs or Chicks Are Needed
A single one is enough. "Ein sham ela efro'ach echad," even where the nest holds no more than one chick, "o beitza achat," or one solitary egg, the finder must first send the mother off and only then take it.
The proof lies in the term the Torah chose for the nest itself: "shene'emar kan." Since the pasuk mentions a "kan" plainly, attaching no condition to it, the derivation follows: "ken mikol makom," whatever sort of nest it may be is included, even one holding just a lone chick or a lone egg.
Which Chicks and Which Eggs Are Excluded
Certain chicks and certain eggs fall outside this mitzvah altogether. "Hayu sham efrochin mafrichin": the young have already grown able to take wing and to forage for themselves; a second case, "o beitzim muzarot," is eggs that no male ever fertilized. In either situation, "patur mishale'ach," the mother need not be sent off. And unfertilized eggs can be recognized: she has brooded over them for a long stretch of time and no chick has taken shape inside.
On what basis is this said? "Shene'emar veha'em rovetzet," and the pasuk continues, "al ha'efrochim," over the chicks, "o al habeitzim," or over the eggs. Young and eggs are thus set together beneath one and the same brooding mother, and the mishnah reads that pairing as a comparison running in both directions.
Reading from the chicks to the eggs: "ma efrochin bnei kayama," the young the verse speaks of are alive, and correspondingly, "af beitzim bnei kayama," the eggs too must hold life within them. They need to be capable of one day becoming chicks, even though the finder will take them long before that day arrives. Hence "yatzt'u muzarot": eggs that were never fertilized are ruled out, since nothing will ever come of them.
Reading in the reverse direction, from the eggs to the chicks: "umah habeitzim tzrichin le'iman," eggs cannot manage without their mother, who must brood upon them and carry them to hatching, and correspondingly, "af ha'efrochin tzrichin le'iman," the young in question must still be dependent on her for their food. Hence "yatzt'u mafrichin": fledglings that fly off and feed themselves are ruled out. They have no further need of her, and the mitzvah does not apply to them.
The Mother Who Keeps Coming Back
"Shilechah vechazrah": he drove the mother off, and she was back at the nest before the eggs were in his hands. Again, "shilechah vechazrah," he drove her off a second time and once more she returned. "Afilu arba'ah vachamishah pe'amim," though the scene repeat itself four or five times over, "chayav," the duty falls on him afresh each time before he may take the young.
"Shene'emar shale'ach teshalach," the pasuk doubles the expression of sending. That repetition rules out any exemption. A person cannot argue that he already fulfilled his part and that her return is her own doing. As long as the mother is there with her young, the eggs may not be taken. He sends her away as many times as it takes until he finally succeeds.
May He Reverse the Arrangement?
"Amar hareini notel et ha'em," a man declares that he would rather keep the mother for himself, "umeshale'ach et habanim," driving off the young in her place. The ruling is "chayav leshale'ach." Such a swap is not his to arrange, since it cuts against what the Torah laid down. He sends off the mother, "shene'emar shale'ach teshalach et ha'em": the pasuk names her as the one to be released, leaving the young to be taken for himself.
The One Case Where He Need Not Send Her Again
We saw that a mother who comes back to the nest must be dispatched a second time. One situation, however, stands apart. "Natal habanim vehechziran laken": having sent her off, he took the young as his own and afterwards set them back inside the nest. "Ve'achar kach," and subsequently, "chazrah ha'em aleihem," the mother came back and settled over them again. The halachah is "patur mishale'ach," he owes her no further sending.
The reason is that once he took the young they became his. They are now "mezuman," ready and available to him, no longer to be regarded as belonging to the mother. And where the eggs or chicks are already at hand in this way, the obligation of shiluach haken does not apply, as we learned in mishnah alef of this perek.