I initially asked this question on Worldbuilding, and a few people said this site would be a better fit. How big is the ziz? Mythology states that it was large enough to block out the sun with its wings, but I'm wondering if that is incorrect. I don't have any information apart from what I can gather from Wikipedia, which I know is often unreliable.
Does anyone have better, more trustworthy info on how big a ziz is?
As you've checked Wikipedia, you're probably aware that the term 'Ziz Sadai' (זיז שדי) first appears in Psalms 50:11 and 80:14, but these passages do not say much about the nature of this entity, other than revealing that it's a bird and appears to have some connection to God.
The legends about the tremendous size of the bird come from Rabbinic literature, mainly from the Byzantine period and onward. In these sources, the Ziz is consistently described as a gigantic bird:
BT (Babylonian Talmud) Bava Batra 73b:
"And Rabba bar bar Ḥana said: Once we were traveling in a ship and we saw a certain bird that was standing with water up to its ankles and its head was in the sky. And we said to ourselves that there is no deep water here, and we wanted to go down to cool ourselves off. And a Divine Voice emerged and said to us: Do not go down here, as the ax of a carpenter fell into it seven years ago and it has still not reached the bottom. And this is not because the water is so large and deep. Rather, it is because the water is turbulent. Rav Ashi said: And that bird is called ziz sadai, as it is written: “I know all the fowls of the mountains; and the ziz sadai is Mine” (Psalms 50:11)."
"Rabbi Menaḥama, Rabbi Bevai, Rabbi Aḥa, and Rabbi Yoḥanan in the name of Rabbi Yonatan said: In exchange for what I prohibited for you, I permitted for you. In exchange for the prohibition of [forbidden] fish, the leviathan is a kosher fish. In exchange for the prohibition of [forbidden] birds, the ziz is a kosher bird. That is what is written: “I know every bird of the mountains; and the ziz of the field is with Me” (Psalms 50:11). Rabbi Yehuda ben Rabbi Simon said: When it spreads its wings it dims the disc of the sun. That is what is written: “Is it through your understanding that the hawk flies, stretches its wings to the south?” (Job 39:26). Why is it called ziz? It is because it has several varieties of taste, from this and from that."
Midrash Shokher Tov on Psalms 18:25 (some manuscripts):
Rabbi Berachiah in the name of Rabbi Yaakov said: ...know My (=God's) sons that a great feast is awaiting you in the World to Come from the feast of the Leviathan, and from Behemoth [and from?] Ziz Sadai, as it is written: "And you shall eat your fill" (Joel 2:26)."
(This midrash suggests that the Ziz, along with the Leviathan and perhaps the Behemoth [the actual phrase, בהמת זיז שדי, Behemoth Ziz Sadai doesn't make sense, so perhaps the passage was distorted over the ages by some scribes] are large enough to be able to provide enough meat for all of the righteous people in the World to Come).
"On the Fifth Day the Holy One, Blessed is He took light and water and created from them Leviathan and its wife, and all of their fish, and hung the entire world from the fins of Leviathan; He mixed them with swamp water and created from them the Ziz Sadai and all the fowl of the sky, and hung the legs of Ziz Sadai upon the fins of Leviathan, and its head against the Throne of Glory..."
It should be noted that another massive bird, called "Bar Yokhnei",1 appears in Rabbinic legends (BT Yoma 80a; Bechorot 57b; Sukkah 5a-b). According to the Talmud in Bechorot 57b, the Bar Yokhnei is identified with a bird mentioned in Job 39:13, "Kenaf Renanim". In the Aramaic Targum on that verse, the name of the bird is translated as "Tarnegol Bara" (תרנגול ברא), 'wild rooster',2 while in the Targum on Psalms 50:11,3 the "Ziz Sadai" is translated with the same phrase: "Tarnegol Bara", which has led some commentators to conclude that the Ziz Sadai may be identified with the Bar Yokhnei (however, it should be noted that these targums weren't authored by the same person/people). In Sukkah 5a-b it's stated that Bar Yokhnei's face is larger than a handbreadth (which in Rabbinic literature is somewhere between 7.6 cm-9.6 cm).
In short, while exact measurements are never given, the Ziz Sadai was consistently viewed as a gigantic bird with the ability to cover the sun. And if the Ziz can be identified with the Bar Yokhnei, then when one of its eggs fell it caused tidal waves and destroy hundreds of towns (Bechorot 57b).
1 Marcus Jastrow proposed that the name was derived from the Varaghna (Bactrian) Ostrich.
2 See also Céline Mangan's translation of the targum here.
3 See also Edward M. Cook's translation of the targum here.
