One must distance his ladder from the dovecote four amos in order that a nemiyah will not jump to (attack) the dovecote.

One person must distance his wall from the rainwater drainage pipe, in order that the pipe owner will be able to stand his ladder there if he needs to fix the pipe.

One must distance his dovecote 50 amos from the city (to prevent the pigeons damaging the vegetable gardens of the city).

One must not build a dovecote within his own property unless there is space around it of 50 amos.

R. Yehudah: There must be a Beis Arba'ah Kur of space (75000 square amos) around it, which is the flying distance of a pigeon.

If he bought the land with a pre-existing dovecote, even if there is only a space of Beis Rovah (roughly 104 square amos) around it, it can remain.

(Gemara) -R. Elazar: (Distancing the ladder from the dovecote is only necessary) when the ladder it to the right side of the dovecote, but if the ladder is to the left side, there is no need to distance it.

Question: Here you said that it must be distanced 50 amos, and there you said (in Maseches Bava Kama) that one may not lay traps for pigeons unless it is 30 ris (which is 4 mil=8000 amos away from an inhabited place?!

R. Yosa ben R. Bun: They look for food within 50 amos, but they can fly up to 4 mil.

(Mishnah): If one found an unfledged chick - within 50 amos of a dovecote, he should return it to the dovecote owner; beyond 50 amos, it may be kept by the finder.

If he found it between two dovecotes, it belongs to the owner of the closer dovecote; if it is equidistant, they divide it.

(Gemara): (It is given to the closer one) only when there is no public thoroughfare separating them, but if there is, it may be kept by the finder.

This case can learn from the case in Bava Metzia (that if a person stayed in an inn and found there lost articles he may keep them. (The Gemara there establishes that the owner had rented it out to three people.) The case there can learn from the case here...

This case can learn from there - if there were only two people, he must announce it.

The case there can learn from here - if there were three people, it belongs to the finder.