Ask the Rabbi: What characteristics make a bird kosher?

birds from the New World represent an intriguing example of the intersection between ancient traditions and new discoveries.

kishon river birdies 311 (photo credit: Kishon River Authority)
kishon river birdies 311
(photo credit: Kishon River Authority)
The Torah provides detailed signs regarding the kashrut of certain animals. Fish require fins and scales, while terrestrial mammals with four legs must have split hooves and chew their cud. Yet the Torah never provides definitive signs for birds or fowl.
Instead, it lists 24 classes of birds that are prohibited (Leviticus 11:13-19).
While a few medieval commentators believe that other forbidden birds might exist (Tosafot Hulin 61a), most assumed that the Torah, by inference, deemed kosher all birds not included in the forbidden list (Ma’achalot Asurot 1:15). Unfortunately we cannot definitively identify the biblically forbidden species, making it difficult to classify the various species of birds.
To solve this conundrum, the Sages provided four identifying characteristics to identify kosher birds, which, unfortunately, did not provide the necessary clarity to resolve these disputes (Hulin 59a). First, a kosher bird is not a predator (dores). While they provided two physical indicators of predators (it spreads two toes to each side while standing on a rope and can consume food mid-flight), the medieval commentators continued to disagree on how to define a “predator” (Beit Yosef YD 82). Some focused on the method of killing, stating that predators claw their prey to death or inject it with venom. Others highlighted the method of consumption, requiring the bird to hold its prey down with claws and break off small pieces, or consume the prey while it is alive.
The Sages further stated that animals with the following three features are kosher: an “extra” toe (sometimes a defensive spur, as with chickens), a gizzard in the digestive tract that can be peeled, and a muscular pouch, or crop, near the throat to store food. The commentators, however, disagreed on whether all four of these criteria must exist to make the animal kosher, or if the presence of some (or all) of the other three signs indicate that the bird is inherently not a predator (Meiri Hulin 61a).
This confusion led 12th-century Rabbi Abraham ben Isaac of Narbonne to bemoan, “We are groping and searching for God’s word and not finding it” (Sefer Ha’eshkol, Simanei Behema 180a).
This frustration, in truth, already existed in the talmudic period, when Jews errantly ate a non-kosher bird, causing much consternation (Hulin 62a). The Talmud further documents that acrimonious debates led stringent scholars to declare that those who ate the disputed bird “will pay the price” in the World to Come (65a).
To solve this problem, some scholars, including Rabbi Yosef Karo, sought to codify the normative physical characteristics and used them to identify kosher birds (YD 82:2-3). He also adopted various other indicators found in rabbinic literature, including the shape of the bird’s eggs (86:1). Yet Karo himself desired an established tradition to attest to the permissibility of the given species. This requirement was unequivocally adopted Rabbi Moshe Isserles, who contended that we can never rely on these disputed identifying characteristics.
One may, however, rely on the traditions of a different locale than one’s own, provided that tradition has bona-fide credibility (84:4).
Transmitting these traditions over the centuries and through different locales, however, is not a simple matter. Before contemporary scientific categorization, it was very difficult to depict the given bird accurately – orally or in writing – especially since the colloquial names for birds differ in various areas. While some felt that written lists were not helpful (Darchei Teshuva 82:34), other scholars wrote pamphlets to painstakingly classify various birds and fowl.
As professors Zohar Amar and Ari Zivotofsky have brilliantly documented, a fascinating debate ensued regarding the status of fowl discovered in the New World, such as turkey and the Muscovy duck, which by definition could not have an old tradition.
One distinguished European scholar, Rabbi Shlomo Kluger (d.1869), asserted that any bird originating in America could not be kosher, since no Jews historically lived there to establish a tradition of kosher birds (Ha’elef Lecha Shlomo YD 1:111). This sentiment initially led some scholars to prohibit Muscovy duck, even as it gained popular acceptance and ultimately rabbinic sanction because it readily crossbreeds with kosher species – which, according to some talmudic interpretations indicates the questionable species is also kosher (Meishiv Davar 2:22).
For some reason, turkey did not share the same controversy and has been deemed kosher for hundreds of years (Arugot Habosem, Siman 16). Some asserted that its de facto consumption (Meishiv Davar 2:22), along with its perceived similarity to chicken (Dvar Halacha 53), create a sufficient “tradition” to continue that consumption.
Others even contended, to much dissent, that the consumption of turkey proves that we may rely upon the talmudic indicators and do not require a bona-fide tradition (Maharam Shick YD 98-100). In any case, birds from the New World represent an intriguing example of the intersection between ancient traditions and new discoveries.
The writer, online editor of Tradition and its blog, Text & Texture (, teaches at Yeshivat Hakotel.
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