Why do we need a Mesorah for Birds?

A startling revelation about the development of the laws of Kashrut

Warning: Some readers may find this post overly technical. However, I think it’s worth the effort to follow it!

In a previous post, I wrote about the laws of kashrut for birds. The Torah lists two dozen types of birds that may not be eaten (shown below in the Hall of Kosher Classification at the Biblical Museum of Natural History). Chazal, aware that it was difficult for people to identify these non-kosher birds, simplified things by giving four signs via which to distinguish kosher from non-kosher birds. These are possessing a hind toe, a crop, a peelable gizzard, and not being “predatory” (to use an imprecise but convenient translation). But it’s a little tricky to understand what Chazal meant.

According to Rashi’s interpretation, the non-kosher birds in the Torah’s list possess the first three of these signs; but in order for a bird to be kosher, it must also be known to be non-predatory. And Rashi says that since it’s difficult to be really sure that a bird is never predatory, one needs a tradition that it is kosher.

However, according to the majority of Rishonim (including Rabbeinu Tam, R. Moshe b. Yosef, Ramban, Ran, Rashba, Ritva, Rif, and others), the birds in the Torah’s list do not possess these three signs; if they were found present in a bird, then this alone would be sufficient, as it would demonstrate that the bird is ipso facto non-predatory. This is not just a dispute about how to understand the Gemara; the Rishonim bring empirical evidence that Rashi’s view is mistaken (namely, that examining the known birds in the Torah’s list reveals very clearly that they do not have all three signs).

You’d expect, therefore, that the Shulchan Aruch and Rema would follow the majority view. And yet they don’t. Shulchan Aruch (Yoreh Deah 82:2) rules that possessing the three signs is insufficient and requires a mesorah to confirm that a bird is kosher, unless it has a bill and webbed feet; Rema requires a mesorah in all cases.

But why? Why adopt Rashi’s view, if it went against the majority view of the Rishonim and had been empirically disproved by Ramban? It’s certainly not what one would expect, based on how halacha normally works. What reason could there be?

It turns out that the answer is readily available. Both R. Yosef Caro and R. Moshe Isserles explain their reasoning in their earlier works, Beis Yosef and Darkei Moshe. The reason is that the Rosh and Rabbeinu Yerucham had raised the concern that the stork seemingly proves Rashi’s concern to be correct.

In Rema’s Darkei Moshe commentary on the Tur, he is explicit about how he initially was going to follow the majority view, and the only reason why he required mesorah was because of the problem raised by the stork:

“…If a bird has the three kosher signs on its body, and also a wide foot and a broad bill in which case it is most certainly not predatory, then it is obvious that one can permit it, for there is nothing to be concerned about. However, in Issur V’Heter Ha-Aruch 3 he writes that one should not eat any bird except from a tradition. And it appears to me to rule the halacha in the same way, because in Toldot Adam V’Chava 15:21 (by Rabbeinu Yerucham) he writes about the cigonia (stork) which nests on tall buildings, and we found that the Rosh wrote, cited by Beis Yosef, rules that it is non-kosher. Thus, even though we see that it possesses all the kosher signs, nevertheless it is not kosher. And therefore one cannot permit any bird on the basis of its possessing signs, only via tradition. And even though one could reject this and say that we are not concerned about rare cases, as we wrote above regarding [another case], nevertheless it appears that one should be stringent in the matter.”

Rema was concerned because the Rosh had objected that some people in Spain were eating storks. Rosh speculated that perhaps they did this because someone had examined storks and found them to possess the three kosher signs. Rosh nevertheless ruled that this would be insufficient, since (following Rashi) it still could be that it is predatory, and there was a firm tradition in Germany and France that the stork is the chasidah of the Torah (which indeed appears to be the correct identification, based on other references to the chasidah in Tanach) - and the chasidah is listed explicitly as one of the non-kosher birds.

It seems that Rema took Rosh’s speculative theory as to how people started mistakenly eating storks – that it was based on finding them to possess the kosher signs - as reflecting a fact. And Rema further referenced Rabbeinu Yerucham, who claimed with certainty that storks possess all three kosher signs, and that moreover they also have webbed feet. This led Rema to be concerned that in rare cases, birds with three kosher signs, and even with a bill and webbed feet, could still be predatory and thus non-kosher.

(Still, due to this view being a minority status among the Rishonim, and due to perceiving it as being an extremely unlikely scenario, it was ultimately only accepted as a stringency. Indeed, Rema himself, in Darkei Moshe, makes his hesitations clear and admits that he is proposing it as a “yesh le-hachmir.” Nevertheless, in his glosses to the Shulchan Aruch, he adds “v’ain leshanot.”)

But in fact, the Rosh’s speculation could not possibly be the real explanation of how the mistaken practice of eating storks began, and Rabbeinu Yerucham’s claims were similarly incorrect. Examinations of storks (such as a halachic dissection at Bar Ilan that I attended) demonstrate that although storks have a peelable gizzard and a hind toe, they do not possess a crop. Furthermore, they clearly do not possess either a bill or webbed feet, as anyone can see by examining the storks that we have on display at the museum. We don’t know why some people were eating storks - perhaps they confused it having two signs with having three signs, or perhaps they were confused with swans, which had a similar name. But it was certainly not due to storks actually having the requisite kosher signs – they don’t.

The Rema thus only decided to adopt a stringency and follow a ruling that was categorically rejected by the majority of Rishonim (in part due to it being empirically disproven) because of a misunderstanding of a situation described by Rosh. It was a stringency adopted in error.

I find it absolutely incredible that in all the voluminous discussion over the years about the kashrut of birds, nobody (including me, up until last week) seems to have ever noticed this!

Still, note that it does not at all necessarily mean that Rema’s view need not be followed. This would depend on one’s general worldview of halacha, for which there is no single approach. For some (such as R. Yosef Shaul Nathanson) the empirical disproof of Rashi’s approach is reason to discount it, and the same would doubtless be true for the empirical disproof of Rema’s concern about storks. Others - probably most - would take the approach that regardless of the validity of the basis for Rema’s stringency, it has generally become accepted practice (with the potential exception of turkey!). Some others might take an intermediate approach, preferring to take Rema’s stringency into account, but allowing the fact that it has a mistaken basis to potentially combine with other factors that may render it irrelevant.

Thus, there are approaches which would accept Rema’s stringency, regardless of its mistaken basis. Still, it would be important to be aware of why one is accepting it.

(Meanwhile, the problem with my publishing a post like this is that it might make people suspect that we will not be following Rema’s view for all the birds being served at the BMNH’s forthcoming Feast of Kosher Curiosities. Rest assured that all species served will be in accordance with Rema’s view - though, naturally, not everyone will agree with our evaluation of what counts as a valid mesorah. And one species in particular will come as an enormous surprise for most people. All participants will be fully informed, and are encouraged to consult with their own halachic authority. Meanwhile, with over 100 seats already taken, there’s a very limited number of places left, so book soon if you’re interested!)