The headline on the e-blast inviting people to Congregation Beth Aaron on Thanksgiving morning was catchy.

“Is your turkey kosher?” it asked. “Are you sure about that?”

One could imagine the panic among desperate housewives. “What?! OMG! If turkey is treif, what will happen to my kosher kitchen? Why did you wait until Thanksgiving to tell me?”

The economic and gastronomic ramifications of turkey being declared a member of the non-kosher bird family were frightening – especially only hours before the start of Thanksgiving dinner.

More than 100 people, ranging in age from six to 75 came to a rabbi talk turkey that morning. The rabbi was Daniel Senter, kashrut administrator at the Kof-K Supervision Service. Senter had the whys and the wherefores at hand, going all the way back to Moses and the mesorah (tradition), which teaches us which birds are kosher and which are not. His talk covered 3,000 years and half the globe. By the time it was over, he was able to assure everyone that turkey, properly slaughtered, was as kosher as a Shabbat chicken.

Using colorful slides, actual livestock (he came complete with a live turkey, a chicken, a partridge, and a quail – all acceptable birds) to make his points, the kashrut expert began his lecture by explaining that the Torah identifies 24 bird species, all predators that are definitely not kosher. It might be assumed, therefore, that any bird not on the list would be kosher. That was not the case, however. Things got complicated because not every bird, including turkeys, had been discovered as yet and, in at least one case, a bird that was considered kosher turned out to be a predator and therefore moved over to the treif column.

What is the difference between a kosher bird and one that is not? Non-kosher birds have talons that are differently configured, and grab branches in a certain way, which Senter described as the “Rope Test.” They swoop down on their prey, sometimes catching it in midair, eat their prey while it is still alive, or tear at it with their beaks.

There are three traits that mark a bird as kosher – they have a different talon configuration than do the predator birds, and include a vestigial leg. They have crops and gizzards that are peelable. Maimonides ruled that the three signs enumerated in the Talmud were reliable, but the commentator Rashi, citing the case of the predator bird that had been previously considered kosher, voided that ruling. Instead, Rashi said, there had to be a mesorah, a tradition, of consumption in addition to the three talmudically ordained signs.

Put another way, if there were no Jewish communities that included a particular ostensibly acceptable bird on their menus, then the bird was not acceptable as food even if it met the Talmud’s three requirements.

For example, everyone agrees that chicken has a mesorah of being eaten by Jews going all the way back to the 7th century B.C.E. Because it has all three signs of being kosher, there was never any question of the acceptability of chicken.

May the same be said, however, for a bird that no one ever heard of before?

That was a theoretical question until Columbus discovered America – and turkeys flew into the picture. The Conquistadors and other early explorers brought these New World birds back home with them, along with tomatoes, cocoa, and other plants. By 1530, turkeys had found their way onto tables in Poland, France, England, and Italy. Jews were raising turkeys in the shtetls of Eastern Europe. The birds were considered kosher because they looked like giant chickens and had all three kosher bird traits – the crop, the gizzard, and the vestigial foot. Still, there was that troublesome ruling from Rashi requiring a mesorah, as well. What was the tradition for a New World bird?

This question can be recast as “what’s in a name.”

Turkey was considered acceptable in the Ashkenazic world of Eastern Europe because it was assumed that there was a mesorah from the Sephardi communities in the Middle East. First, the American birds were being traded by Turkish merchants (which is why we call the bird a turkey). Second, in some parts of Europe, and both in Hebrew and Arabic, the bird was called a “hodu,” indicating that it came from India and there thus was a tradition.

Needless to say, there was much confusion until the definitive halachic decisor for Ashkenazic Jewry, Rabbi Moshe Isserles (1520-1572) of Krakow, “drew a line in the sand.” He ruled that only those birds known to be eaten by Jewish communities at the time of his ruling were allowed. This included the turkeys – but only just. Any new species of birds, however, were not to be considered kosher even if they met the three requirements.