Mishna:
If he prepared black birds and found white ones, or he prepared white birds and found black ones [the Gemara will ask that this is obviously superfluous to say, since these birds were certainly not prepared], or if he prepared two birds and found three; they’re all forbidden [although it’s possible that only one is new, it is not battel because it’s a davar sheyesh lo mattirin (009)].
If he prepared three birds and found two; they’re permitted. If he prepared them inside the nest and found them in front of the nest [on the little porch], they’re forbidden. If no other nests are nearby, they’re permitted.
Gemara:
Question: It’s superfluous to say that birds of another color are forbidden?
Rabbah: We’re discussing a case where he prepared both black and white and then found that they had switched places on Yom Tov, we might think they’re the same birds but switched places, so the Mishna teaches that actually they’re different birds.
There are two possibilities here. A. We assume they are the same birds, because they are nearby. B. We assume they are new birds because there are so many birds in the world, that the majority is new birds.
Suggestion: It would seem that this is proof to Rabbi Chanina.Rabbi Chanina: When there is a conflict between Rov [majority] and Karov [nearby], we follow Rov.
Response: It is as Abayye said (047): On the platform. Here too, the Mishnah is discussing a platform [the platform is an invitation to all passing birds to alight, and so all faraway birds are also nearby birds, because we assume they will stop by].
[We actually do follow Rabbi Chanina, only that there is no proof to him from our Mishnah]. 
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