How do we know which animals are kosher?
According to the Mishna (59a), although the Torah offers indicators for animals – split hooves and chewing its cud – it does not do so for birds. Nevertheless, the Sages established a number of indicators for birds:
- A bird that is a dores – it hunts its prey – is not a kosher bird
- A bird that has an extra toe, a crop, and a gizzard that can be peeled is a kosher bird.
The Gemara on today’s daf offers the source for these rules. The baraita teaches that the nesher is mentioned as one of the non-kosher birds and we know that a tor is a kosher bird since it is brought as a sacrifice. We can therefore conclude that:
Just as the nesher is unique in that it has neither an extra toe nor a crop, its gizzard cannot be peeled, it claws its prey and eats it, and is not kosher, so all that have similar characteristics are not kosher.
Torim have an extra toe and a crop, their gizzard can be peeled, they do not claw their prey and eat it; just as they are kosher, so all that have similar characteristics are kosher.
Traditionally, the nesher has been identified as an eagle, a bird of prey that is called an ayit in modern Hebrew. Rabbeinu Tam argues that this identification cannot be correct, since eagles do have an extra toe. The Ramban adds that according to a passage in Sefer Mikha (1:16) it appears that the nesher is bald, which would preclude identifying it as an eagle. An alternative identification is the gyps fulvus or griffon vulture, a bird of prey that has a very white bald head, very broad wings and short tail feathers.
In contrast to the nesher, the baraita points to the tor as the archetype kosher bird. In fact, the Torah does not list any kosher birds; the entire list of 24 birds mentioned in the Torah (see 11:13-19) are non-kosher. According to the Torah (Sefer Vayikra 1:14), the two types of birds that can be brought as sacrifices are torim and benei yona – turtledoves and pigeons. The tor that is referred to is identified as Streptopelia turtur, while the yona is identified as Columba livia domestica. Since they are brought as sacrifices, the Gemara assumes that they must be kosher for mundane purposes, as well.