Ibn Ezra and the transsexual rabbits

In parashat Shemini, the Torah prohibits us from consuming certain animals:

ד  אַךְ אֶת-זֶה, לֹא תֹאכְלוּ, מִמַּעֲלֵי הַגֵּרָה, וּמִמַּפְרִסֵי הַפַּרְסָה:  אֶת-הַגָּמָל כִּי-מַעֲלֵה גֵרָה הוּא, וּפַרְסָה אֵינֶנּוּ מַפְרִיס--טָמֵא הוּא, לָכֶם.	4 Nevertheless these shall ye not eat of them that only chew the cud, or of them that only part the hoof: the camel, because he cheweth the cud but parteth not the hoof, he is unclean unto you.
ה  וְאֶת-הַשָּׁפָן, כִּי-מַעֲלֵה גֵרָה הוּא, וּפַרְסָה, לֹא יַפְרִיס; טָמֵא הוּא, לָכֶם.	5 And the rock-badger, because he cheweth the cud but parteth not the hoof, he is unclean unto you.
ו  וְאֶת-הָאַרְנֶבֶת, כִּי-מַעֲלַת גֵּרָה הִוא, וּפַרְסָה, לֹא הִפְרִיסָה; טְמֵאָה הִוא, לָכֶם.	6 And the hare, because she cheweth the cud but parteth not the hoof, she is unclean unto you.
ז  וְאֶת-הַחֲזִיר כִּי-מַפְרִיס פַּרְסָה הוּא, וְשֹׁסַע שֶׁסַע פַּרְסָה, וְהוּא, גֵּרָה לֹא-יִגָּר; טָמֵא הוּא, לָכֶם.	7 And the swine, because he parteth the hoof, and is cloven-footed, but cheweth not the cud, he is unclean unto you.

Most of these are described using the masculine gender. The exception to this rule is the arneves, commonly translated as the hare. Ibn Ezra discusses the reason for the rule, and its exception:

והזכיר: הגמל והשפן והארנבת והחזיר -
בעבור שיש לכל אחד הסימן האחד ודרך לשון הקדש להזכיר הזכר מכל מין כי הנקבה בכלל הזכר היא.

והזכיר ארנבת -
יש אומרים:
לפי שלא ימצא הזכר מהם.

ויש אומרים:
שהזכר ישוב נקבה והפך הדבר והראשון קרוב אלי.

That is, in terms of why the masculine is used in general for these species, this is not the masculine but the neutral gender, which encompasses both sexes. The word arneves seems clearly feminine, though, with the -es ending. Ibn Ezra presents two answers. The first answer, that some give, is that the male of the species does not frequent human areas, such that people typically find the female. Therefore, dibra Torah behoveh. (Or else he means that therefore the gender-neutral name of the species became the feminine name; but I think he meant dibra Torah behoveh.) The second answer, that some give, is that the rabbit switches genders -- the male turns into the female, and the opposite as well. And the first answer seems more likely to him. I am not sure whether it recommends itself to him more as grammatical point, or whether he disbeleives one or the other scientific, zoological claim (presence of males, or whether it switches genders).

I don't know who, before Ibn Ezra, suggests either of these two suggestions. I haven't found anything suggesting that the gender proportions of rabbits weigh more heavily towards females, so I will leave it at that, and explore the second suggestion, that the rabbits switch genders.

Such is not entirely crazy. We do see certain animals capable of switching genders. To cite one article:

Shrimp do it, orchids do it, even some tropical fish do it. Now biologists find that frogs do it, too--switch their sex, that is. A West German research team reports that females of two related frog species can become males without hormonal or surgical intervention. So complete is the transformation -- observed so far only in the laboratory -- that the newly male frogs breed successfully with members of their former sex.

Of course, that does not mean that it happens in mammals, such as the rabbit. This seems rather unlikely, from what I think we know about the world. But then, I am no expert on zoology. Perhaps some further discovery will show mammals which can perform this trick. But that does not mean that rabbits are capable of this. At some point, there are visible, signs, such as descended testicles, etc. See here for a text description of how to tell the difference. It is difficult to imagine that some developed body part would disappear, or switch, from one year to the next.

It appears much more likely that Ibn Ezra was citing a zoological position which is simply incorrect, though which was believed correct at his time. There is no shame in believing the scientific experts of one's era, and attempting to use such scientific knowledge to explain a pasuk, even if eventually it turns out that the scientific belief was incorrect. This is simply good Torah Umaddah which came to a wrong conclusion. (Though in this instance, Ibn Ezra preferred the former explanation, and so did not wholeheartedly endorse the latter.)

From rabbit.org, here is another recording that a rabbit can its gender:

A number of explanations account for this hare/moon symbiosis. One is that the hare is nocturnal and feeds by night; another is that the hare's gestation period is one month long. And, it was believed that a rabbit could change its sex—like the moon.

I am not certain what their source is for this, but it does tell me that there is indeed some source out there. I found a book, Christianity, Social Tolerance, and Homosexuality: Gay People in Western Europe from the Beginning of the Christian Era to the 14th Century, by John Boswell, which happens to mention that ancients believed in quite similar traits for rabbits, and the precise trait for hyenas, and that they connected it with the non-kosher status of these animals. Thus,

and

Thus, we have Ibn Ezra's assertion, directly made about the hyena, with the assumption that Moshe Rabbenu spoke about the hyena. In a footnote (not pictured), the author explains how this came about -- a mistranslation of a word, elsewhere, for pig. But many ancient natural historians believed this. And "Pliny cites Archalaus that rabbits are hermaphroditic and the conceive while pregnant. Aelian relates that the male hare bears young and 'has a share in both sexes.'" And all this is relatively early, but these early accounts were quite often believed into medieval times.

What about the hare's behavior would make people believe this? We can only guess. But here is my guess. From a Yahoo Answers page: What age can you tell a rabbit's gender? The best selected answer, from cwgirlup2000, was:

An experienced breeder or vet can tell you sooner, but around 3-6mo a male rabbits "boy bits" will drop and it is pretty obvious when this happens.

Source(s):

My own boy rabbit

So they might have looked earlier, not been able to determine that it was a male rabbit, but subsequently found that it was male. Thus, a transformation in gender.

At answerbag, someone explicitly asks if rabbits can change gender. Some good answers:

No. Mammals are pretty much whatever sex they are born, human sex-change operations and accidental hermaphrodites notwithstanding.

Be aware that female rabbits can also display aggressive "mounting" behavior. However, they are still female and will not be able to make another female pregnant.

If so, perhaps ancient zoologists saw this mounting behavior and erroneously believed that the female rabbit became male; or that it was a hermaphrodite. Another good answer:

No. If you suspect it it means someone didn't know how to sex the rabbits correctly in the first place. It isn't so hard to tell if you know what to look for but I've noticed that most people expect that a male rabbit look like a 'male' from early on. They don't have a penis that sticks out nor do they have testicles showing until they are several months old. But you can still tell the difference from the shape of their opening.

Which is how one could confuse. Also, accidentally placed as an answer, and plausible for our question, males as well exhibit homosexual behavior. See there. If so, they might have believed that the male had become female. And before we saw how they might have believed that a female had become male.

Mechokekei Yehuda, a supercommentator of Ibn Ezra, tells us more,

Thus, he cites רב"ח (=Rabbenu Bachya) that hares are hermaphroditic, and have both male and female genitals. And cites R' Eliyahu Bachur, in Tishbi, shoresh gilgul, that they are רובע ונרבע. Bachur's statement on gilgul is interesting in its own right, in how he distinguishes Chazal's gilgul from kabbalah's gilgul, the former merely being rolling underground to reach Eretz Yistael at the time of techiyas hameisim:

He mentions a kabbalistic belief that male homosexuals come back as rabbits, because of their רובע ונרבע aspect. Fascinating.

Update: Rabbi Slifkin mentions some of the above in his book, The Camel, The Hare, and The Hyrex. (That is, some of the Jewish and Greek sources; not the early Christian material or my particular explanation of how this misconception could arise.) Looking at some of the footnotes from his book, here is another interesting source. From Midrash Talpiyos (last mentioned in the context of number of teeth):

That is, arneves turns from male to female. And this is known to us in truth. (And this is the reason that a male homosexual comes back as a gilgul as a rabbit, as the Arizal writes.)

And we have the following in Pseudodoxia, from Sir Thomas Browne:

And here is Rabbenu Bachya: