I own a female rabbit and my neighbor owns a male rabbit. The two rabbits are together frequently. When my rabbit gave birth to a litter of rabbits, my neighbor claimed that he deserves some of the newborn rabbits since his rabbit impregnated my rabbit. Is he correct?
Even though the particular question does not come up frequently, the question involves several important principles which have broad applications.
This case is not discussed in the Gemara but there are two sections of Gemara that are relevant.
The Mishna (BM 100B) discusses a situation where a strong current of a river washed a person’s olive tree downstream and it took root in another person’s field and bore olives. Both the original owner of the tree and the owner of the field in which it grew claimed that he was entitled to the new olive crop, since his property was the cause of the new crop of olives. The Mishna rules that each one is entitled to half of the new crop.
The Gemoro (BM 101A) clarifies that this ruling of the Mishna is limited to the first three years after the tree takes root and only where not only the tree was washed downstream but also enough of the original surrounding soil to allow the tree to stay alive was embedded at the new location along with the tree.
The background for this halacha and for these conditions is that when one plants a tree the Torah forbids eating or deriving any gain from the fruit of the first three years after it takes root since in those years the fruit is orloh. However, if a tree which already was planted for three years, is replanted together with enough surrounding soil to maintain the tree, the fruit is permitted immediately since the tree already grew for three years in its previous location and its growth at the new location is considered a continuation of the original growth and not a new planting.
Based on these halachos, the Gemoro explains the ruling of the Mishna that the fruit is divided. Since the owner of the land could not have produced consumable olives during the first three years following the implantation of the tree, the owner of the tree shares in the olive crop. However, once three years elapse, since the owner of the field could have derived benefit from an olive tree had he planted one at the time that this tree was planted, the owner of the tree is no longer entitled to any of the new olives even though they grew on his tree.
The Rashba asks that if the tree could have lived with the soil that got washed along with it, why isn’t the tree owner entitled to all of the fruit in the first three years since the tree didn’t need the field at all? He answers that if the soil that came along with the tree could have fully sustained it, the tree owner is in fact entitled to all the fruit. However, in the situation that the Gemoro discussed, the soil that was washed along with the tree was only enough to keep the tree alive, but not enough to produce fruit. Since the owner of the tree could not have produced fruit without the field, the owner of the field is entitled to half of the fruit.
Thus, the reason they split the fruit of the first three years is because neither the tree alone nor the land alone could have produced the crop. Since both were needed, they split the crop. The approach of the Rashbo is cited by the Magid Mishne (Shecheinim 4, 10) and the Sema (CM 168, 3).
The Ra’avad (cited by the Shitto Mekubetses) answers the Rashbo’s question differently. Even if the soil was sufficient to produce fruit, the owner of the land can demand a share because the olive tree prevented him from using his land to produce something else. However, it is important to note that the Ra’avad only offers this answer according to an explanation of the Mishna by the Gemara which is not authoritative. Therefore, it is not clear that he disagrees with the Rashbo.
The Shulchan Aruch (CM 168, 1) rules this case and, based on Tosafos and the Rashbo, adds that the owner of the field must pay the owner of the tree at the end of the three years for his tree. The amount he owes is the amount tree was worth when it became implanted in his field. The reason he only has to pay for the value at the time the tree became implanted and not for its present value after the three years is because the added value is due to the input of the field.
Thus, based on the Rashbo’s approach, we can derive from the Gemara’s ruling concerning the fruit of the first three years, the important principle that even though the fruit grew because of the land, if the land could not have produced this fruit without the input of the tree, the owner of the tree is entitled to half of the land’s produce. Similarly, since the tree itself was incapable of producing fruit without the land, the owner of the land is entitled to half of the produce.
Furthermore, we see from the Rashbo that even though the tree sat on the land, if the land was not needed to produce the fruit, the tree owner is entitled to all of the fruit even though the owner of the land could have used the land for something else.
The Chida (res 7) was asked to rule concerning a case that is somewhat similar to yours. In his case, A placed ten eggs under his chicken to hatch them. Without informing A, B additionally placed five of his eggs under A’s chicken. When fifteen chickens hatched, B told A he must give him five of the chickens because they hatched from his eggs. A replied that he need only give him five eggs because that is all he received from B.
The Chida first brings the ruling of Rav Shabsei Ghermezian who ruled that B is correct that he is entitled to five chickens. He based his ruling on his understanding of the Gemara. He understood that the reason they split the olives for the first three years is that both parties are somewhat correct. The contribution of the owner of the tree is that his tree was needed in order to produce the olives since it was in the first three years but he must share the produce with the owner of the field because he could have planted something else. He says that really the amount he is entitled to is what he could have produced, but since we don’t know how much that is, the Chachomim chose to give the field owner half.
Based on his understanding of the Gemoro, Rav Shabsei ruled that the owner of the five eggs is entitled to the chickens that hatched from his eggs because the owner of the chickens suffered no loss on account of these eggs since he only placed ten eggs and was not planning to place more eggs.
The Chida disagrees with Rav Shabsei because the expressions of the Gemara indicate that the reason the owner of the land is entitled to half is because of the input of the land in the produce and not because of a loss. Based on this, he first wanted to rule that they should split the five extra chickens. He then backtracked a bit saying that even though the main reason the owner of the field gets half of the olives is because of his field’s contribution towards the production of the olives, nevertheless, we also need the claim that he suffered a loss because he could otherwise have planted something else. Therefore, in the case of the eggs he agreed with Rav Shabsei, saying that if the owner of the chicken was not aware that eggs were placed under his chicken, all the chicks belong to the owner of the eggs since the owner of the chicken suffered no loss.
We note that the Yabia Omer (4, CM 4, 3) asks that it is likely that the hen’s owner had some loss because the hen probably became weaker because of the extra eggs it needed to sit on. Therefore, according to the Chida they should split the five chickens.
It seems that the Rashbo agrees with the Chida’s first approach since the Rashbo indicates that if both of the sources are necessary in order to produce the profit, the two owners split the profit even if no loss was suffered by the owner of the land. Therefore, if one can compare the Chida’s case to this Gemara it seems that in any case the owner of the chicken should share in the chicks.
However, it is not obvious that one can compare the Chida’s case to this Gemara since even though it was necessary to have the hen sit on the eggs in order to produce the chicks, the hen does not contribute to the production of the chickens the way a field contributes to the production of olives. In the case of the Gemara, the field provides the tree with the nutrients which enable it to produce fruit. In contrast, the hen merely provides a warm environment to enable the eggs to hatch, a task performed today by ovens. This point is noted by the Pri Yitzchok (1, 15). The Pri Yitzchok concludes that whether a chicken sitting on eggs is comparable to a field is a dispute in the Yerushalmi.
The principle that we derived from the Rashbo that if two sources are needed to produce a profit the profits are split, is seen elsewhere as well. The Gemara (Kesubos 98B) rules that if a person sends an agent to buy something for him and the agent receives more than expected for the money that he paid, the extra goods are split between the agent and the customer who paid for the purchase. The Rif (57B) says the rationale of the Gemara is that even if the extra item was given expressly to the agent, he must nevertheless split it with the customer since without the customer’s money he would not have received the present. Again, the principle is that if two factors are necessary in order to earn the extra amount it must be split between both factors since each was necessary in order to earn the profit.
Returning to your question, based on the above it seems that according to the Chida your neighbor is entitled to half of the newborn rabbits since your neighbor “lost” something since the male rabbit used his nutrients and became a drop weaker as a result of producing the sperm to impregnate your rabbit.
Even according to the Pri Yitzchok perhaps he is entitled to half of the rabbits because the contribution of the male rabbit is greater than the contribution of the hen that sat on the eggs.
However, there are many poskim who rule that you can keep all of the rabbits since the rabbits came from the female and the male only contributed sperm. This was the understanding of the Radvaz (res 598), Maharit Algazi (Kehillas Yacov Tosefos Derabbonon letter ayin siman 251 page 315) and the Sefer Yehoshua (res 37), who explains that the sperm is like saliva and we consider the child to be the offspring of the female. This is also the understanding of the Imrei Moshe (siman 26) and Rav Eliashev (He’oros, Gittin 43A).
Finally, since you are in possession of the baby rabbits and your neighbor seeks to take them away from you, even if the issue is in doubt, you may keep the young rabbits and not give or pay your neighbor anything.