Leviticus 11: Go Birds!

Chapter 11 discusses what makes animals kosher. Land animals need to chew their cud and have split hooves. The Torah then gives examples of which animals do one but not the other- camels, pigs, and rabbits. For fish, scales and fins are required. The Torah does not give examples of fish that are not kosher. Creepy crawling animals and bugs are forbidden in their entirety except for certain grasshoppers. Then comes birds. For birds the Torah does not list certain features, it simply lists 24 different birds. The complicated part of this list is deciphering which birds are mentioned. Many of the English translations are simply guesses as to the identity of the birds. Commentators try to match the names with other uses in Tanach or other languages. The Gemara in Chullin 60b quotes the Mishnah which states that the Torah did not provide signs for kosher birds. The Gemara then explains that through the list of non-kosher birds and known kosher birds one can deduce the signs of a kosher bird. The two birds that are discussed are a nesher as the non-kosher bird and the dove as a kosher one. There are four things the dove had that the nesher does not. The nesher does not have an extra toe, it does not have a crop, it does not have a gizzard that can be peeled and it claws its prey to eat it. Doves have an extra toe, they have a crop, its gizzard can be peeled, and it does not claw its food to eat. Any animal that has four signs that match either of these birds is either kosher or not kosher. The Gemara then proceeds to spend multiple pages discussing different scenarios of birds that have some signs, but not all signs, and at the same time are not listed in the Torah, whether or not these birds are kosher. The bottom line is that it is not straightforward. Rav Shimshon Rafael Hirsch explains that bird species are so numerous that it would be too difficult to have generalized classifications of simanim like animals and fish. In modern times this issue arose with turkeys. Some halachic authorities held that because of the confusion surrounding the list of non-kosher birds in the Torah, one could only eat birds for which there was a tradition that it was kosher. Turkeys were only brought to Europe in the 1500s, so there was no long-standing tradition regarding their kosher status. Others took the opposite approach. Because there was a tradition listing all 24 of the non-kosher birds in the Torah, any bird not listed should be considered kosher. A third group looked at the signs listed in the Gemara and also matched the turkey with a chicken (even though it is more like a pheasant, which is also kosher). Based on these signs and the closeness to the chicken, the turkey was deemed to be kosher.