Related for Beitzah 1:4
זִמֵּן שְׁחוֹרִים וּמָצָא לְבָנִים, לְבָנִים וּמָצָא שְׁחוֹרִים, שְׁנַיִם וּמָצָא שְׁלֹשָׁה, אֲסוּרִים. שְׁלֹשָׁה וּמָצָא שְׁנַיִם, מֻתָּרִים. בְּתוֹךְ הַקֵּן וּמָצָא לִפְנֵי הַקֵּן, אֲסוּרִים. וְאִם אֵין שָׁם אֶלָּא הֵם, הֲרֵי אֵלּוּ מֻתָּרִים:
If he prepared black and found white, white and found black (they are forbidden). [This (as it stands) is obvious and need not be stated. What is meant is that if he prepared black and white, and found black in the place of white, and white in the place of black, etc. And this is how our Mishnah is to be understood: If he prepared black in one nest and found white in it; and if he prepared white in another nest and found black in it — we might think that they are the same birds and that they changed nests; we are, therefore, apprised otherwise.] (If he prepared) two and found three [and he does not recognize those he prepared], they are [all] forbidden. (If he prepared) three and found two, they are all permitted. [For we assume that one left and the other remained, and we do not say that just as one left so they all left and these are other birds.] (If he prepared them) inside the nest and found them outside [and found nothing inside the nest], they are forbidden. And if they were the only ones there [in the dove-cote], they are permitted. [And even if there is another dove-cote within fifty cubits of it, if that dove-cote is not aligned with this one, but in a corner, we do not surmise that it might have come from that dove-cote; for fledglings, so long as they do not fly, but hop, hop only to a nest aligned with theirs, only, if when they turn around, they can see their nest.]