Rav Yosef had small date trees. Bloodletters sat under them. Ravens came to eat the blood of their Kelim, and perched on the trees, and damaged the dates.

Rav Yosef: The bloodletters must leave!

Abaye: It is only Grama!

Rav Yosef: Rav Tuvi taught that Grama of damage is forbidden.

Abaye: They are Muchzak to sit there!

Rav Yosef: Rav Nachman taught that there is no Chazakah for something that damages.

Abaye: Rav Mari taught that that refers to smoke, and Rav Zevid taught that it refers to a Beis ha'Kisei (a privy. It does not apply to other things!)

Rav Yosef: I am very sensitive. The ravens bother me like smoke and a Beis ha'Kisei.

(Mishnah): One must distance a dovecote 50 Amos from a city.

One may not make a dovecote in his property unless he owns 50 Amos around it in every direction;

R. Yehudah says, he must own (the area in which one seeds) four Korim. This is as far as birds fly.

If one bought a dovecote, even if it is very close to neighbors, he is Muchzak (and may keep it).

(Gemara) Question: Fifty Amos is not enough!

Contradiction (Mishnah): We may not set traps for doves within four Mil (a Mil is about a kilometer) of a settled area.

Answer (Abaye): They can fly further, but they eat their fill within 50 Amos.

Question: They can fly more than four Mil!

Contradiction (Beraisa): In a settled area, one may not set traps within 100 Mil!

Answer #1 (Rav Yosef): That is when vineyards are in between (it flies from vineyard to vineyard).

Answer #2 (Rava): That is when other dovecotes are in between.

Question: If so, one may not spread traps due to the other dovecotes!

Answers: The trapper owns the other dovecotes, or a Nochri owns them, or they are Hefker.

(Mishnah): R. Yehudah... (If one bought a dovecote, even if it is very close to neighbors, he is Muchzak).

(Rav Papa): This teaches that we suggest claims on behalf of buyers and heirs.

Question: A Mishnah explicitly teaches that we claim on behalf of heirs!

(Mishnah): An heir need not explain how the one who bequeathed to him received the property.

Answer: Rav Papa needed to teach about buyers.

Question: A Mishnah also explicitly teaches that we claim on behalf of buyers!

(Mishnah): If one bought a Chatzer with ledges sticking out (over the Reshus ha'Rabim) he is Muchzak (that he is entitled to them).

Answer: We must teach both cases.

Had we taught only that case, one might have thought there we argue for a buyer, for perhaps the area under them was really part of the Chatzer, or the public allowed the previous owner to build them, but we would not argue for one who buys a dovecote.

If we only taught about a dovecote, one might have thought that the previous owner appeased the neighbor, or the neighbor allowed him;

But we would not assume that one appeased or obtained pardon from the public!

(Mishnah): He is Muchzak.

Question: Rav Nachman taught that there is no Chazakah for damage!

Answer #1 (Rav Mari): Rav Nachman refers to damage of smoke.

Answer #2 (Rav Zvid): He refers to a Beis ha'Kisei.

(Mishnah): A chick found within 50 Amos of Reuven's dovecote belongs to Reuven;

If it is more than 50 Amos away, the finder keeps it.

If it is found between two dovecotes, it belongs to the owner of the closer one;

If it is exactly in the middle, they divide it.

(Gemara - R. Chanina): When in doubt about where something came from, we assume that it came from the majority, even if the minority is closer.

Even though the Torah says that we follow the majority, and that we attribute to the closest source, the majority is stronger.

Question (R. Zeira): "Ha'Ir ha'Kerovah" - we attribute (an unknown murderer) to the closest city, even though other cities have more people!

Answer: No, the Torah selects the closest city only when the populations are equal.

Question: If we follow the majority, we should assume that the murderer came from the rest of the world (not from the closest city)!

Answer: The case is, the area is surrounded by mountains (so we do not suspect that the murderer came from further away).

Question (Mishnah): A chick found within 50 Amos of Reuven's dovecote belongs to Reuven;

Even though there are dovecotes with more birds, we assume that it came from Reuven's!

Answer #1: The case is, no dovecote in the area has more birds.

Objection (Mishnah): If it is more than 50 Amos away, the finder keeps it.

If no dovecote in the area has more birds, surely it came from Reuven's!

Answer #2: The chick cannot fly, it only walks.

(Rav Ukva bar Chama): A chick does not walk more than 50 Amos. (If it is not within 50 of any dovecote, we must say that it flew. We assume that it came from elsewhere in the world.)

Question (R. Yirmeyah): If one leg is within 50 Amos and the other is outside, what is the law?

R. Yirmeyah was expelled from the Beis Medrash for this (Rashi - for asking too many questions; Tosfos - for not accepting that it cannot walk more than 50 Amos).

Question (Mishnah): If it is found between two dovecotes, it belongs to the owner of the closer one.

This is even if one has more chicks than the other!

Answer: No, both have the same amount.

Question: We should assume that it came from elsewhere in the world (since it cannot walk more than 50)!

Answer: The case is, it was found on a path between vineyards, so it can walk more than 50;

It could not have come from another dovecote, since a chick will never walk out of sight of its nest (and these are the only two dovecotes in sight).