Proof text in Rosh Hashanah for month of mating season

Question

The Gemara in Rosh Hashanah on 11a says:

ר' יהושע אומר מנין שבניסן נברא העולם שנא' (בראשית א, יב) ותוצא הארץ דשא עשב מזריע זרע ועץ עושה פרי איזהו חדש שהארץ מליאה דשאים ואילן מוציא פירות הוי אומר זה ניסן ואותו הפרק זמן בהמה וחיה ועוף שמזדווגין זה אצל זה שנאמר (תהלים סה, יד) לבשו כרים הצאן וגו'

Rabbi Yehoshua says: From where is it derived that the world was created in the month of Nisan? As it is stated: “And the earth brought forth grass, herb yielding seed after its kind, and tree yielding fruit” (Genesis 1:12). Which is the month in which the earth is full of grass and the trees begin to bring forth fruit? You must say that this is Nissan. And further proof that the world was created in Nissan is that when the world was first created, the animals had to breed in order to fill the world, and the period beginning with Nisan is a time when cattle, and beasts, and birds mate with one another, as it is stated: “The flocks are clothed in the meadows, and the valleys are wrapped in grain; they shout for joy, they also sing” (Psalms 65:14).

Yet earlier in Rosh Hashanah (8a) the Gemara establishes that this text demonstrates that animals primarily mate in Adar:

אלא אמר רבא דכ"ע לבשו כרים הצאן בזמן שעמקים יעטפו בר באדר

Rather, Rava said that the dispute must be explained as follows: Everyone is of the opinion that “the flocks are clothed in the meadows,” i.e., the sheep conceive, primarily at the time when “the valleys are wrapped in grain,” in the month of Adar.

It's important to note that the Gemara on 8a seems to assume a significant difference between Adar and Nissan. We see this from a machloket there about whether R"H for ma'aser beheima is in Elul or Tishrei. This is based on an argument from this passuk about whether or not the animals primarily mate in Adar or Nissan. Thus it appears that Adar and Nissan are different enough in terms of when the mating period is.

Therefore, my question is how can our Gemara use this passuk as a proof for R' Yehoshua that creation happened in Nissan?

Answer 1

A potential answer is as follows:

R. Yehoshua is not adducing a formal proof when he quotes the verse לבשו כרים הצאן. It is simply an additional support. He is saying that I said that creation was in Nissan and you said that creation was in Tishrei, and it makes more sense for it to have been in Nissan because Nissan is around the mating time and Tishrei is not.

This does not mean that he is saying that Nissan is the exact and only time that animals mate. Indeed, he doesn't even say that Nissan is the month (חודש) of mating (as he does with his first proof); he says it is the time (פרק) of mating, which means it is around the time of mating. If the time of mating was three months long (Adar-Sivan) this would still be correct, and it would be evidence that Nissan is more likely than Tishrei to have been the month of creation.

Indeed, when we look back at the passage on 8a, we find that it does not say that only Adar is the time of conceiving. The Talmud first presents it as a dispute amongst tannaim whether the majority conceive in Adar with a minority in Nissan, or the majority conceive in Nissan with a minority in Adar. Even if the passage on 11a accepts Rava's conclusion from 8a that everyone agrees that most animals conceive in Adar, there is still the minority of animals that conceive in Nissan.

Thus, if we know that some animals conceive in Nissan, and the rest of them conceive in Adar which is the same "time period" as Nissan, it is fair to assume that the world was created in Nissan over Tishrei, because that would allow the animals to mate.

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I subsequently found that R. Shmuel Strashun also raises this question, and answers similarly that the Talmud on 8a grants that some animals mate in Nissan.

Hagahot V'Chidushei HaRashash, Rosh Hashanah 11a

ואע"ג דמסקינן לעיל (ח) דלכ"ע לבשו כו' בזמן דעמקים כו' דהיינו באדר מ"מ כיון דאותן שלא לבשו באדר מתלבשות בניסן כדאמר שם ואיכא נמי כו' שפיר הוי זמן זיוג להנבראים עתה