Chullin 140b ~ Ornithology, Emotions, and the Reasons for the Commandments

We are just two days away from finishing the long tractate called Chullin, which dealt with all manner of questions about kosher meat and poultry. In the final chapter we are studying the details of a rather different issue: the command to frighten away the mother bird if you wish to eat the eggs she is incubating. This commandment is called שילוח הקן – shiluach haken, (lit. “sending away the nest”). We will discuss some ornithological issues and see how they might impact our understanding of the command.

Here are the details in the Torah:

דברים כב,ו–ז

כִּ֣י יִקָּרֵ֣א קַן־צִפּ֣וֹר ׀ לְפָנֶ֡יךָ בַּדֶּ֜רֶךְ בְּכָל־עֵ֣ץ ׀ א֣וֹ עַל־הָאָ֗רֶץ אֶפְרֹחִים֙ א֣וֹ בֵיצִ֔ים וְהָאֵ֤ם רֹבֶ֙צֶת֙ עַל־הָֽאֶפְרֹחִ֔ים א֖וֹ עַל־הַבֵּיצִ֑ים לֹא־תִקַּ֥ח הָאֵ֖ם עַל־הַבָּנִֽים׃ שַׁלֵּ֤חַ תְּשַׁלַּח֙ אֶת־הָאֵ֔ם וְאֶת־הַבָּנִ֖ים תִּֽקַּֽח־לָ֑ךְ לְמַ֙עַן֙ יִ֣יטַב לָ֔ךְ וְהַאֲרַכְתָּ֖ יָמִֽים׃

If, along the road, you chance upon a bird’s nest, in any tree or on the ground, with fledglings or eggs and the mother sitting over the fledglings or on the eggs, do not take the mother together with her young. Let the mother go, and take only the young, in order that you may fare well and have a long life.

That’s it. Two sentences. But have no fear - there are at least twelve pages of discussion about this in the Talmud, which raises all sorts of questions. Like this one, asked by Rabbi Zeira:

חולין קמ,ב

בעי ר' זירא יונה על ביצי תסיל מהו תסיל על ביצי יונה מהו

If a yonah (pigeon) is resting upon the eggs of a tasil, [a kosher bird resembling a pigeon,] what is the halakha with regard to sending away the mother bird from the nest? Likewise, if a tasil is resting upon the eggs of a yonah (pigeon), what is the halakha?

אמר אביי ת"ש עוף טמא רובץ על ביצי עוף טהור וטהור רובץ על ביצי עוף טמא פטור משילוח הא טהור וטהור חייב דלמא בקורא

Abaye said: Come and hear that which is taught in the Mishna (on 138b): In a case where a non-kosher bird is resting upon the eggs of a kosher bird, or a kosher bird is resting upon the eggs of a non-kosher bird, one is exempt from sending away the bird. One may infer from the mishna that in a case involving a kosher bird and kosher eggs, [e.g., a tasil resting on the eggs of a pigeon, one is obligated to send away the mother bird. The Gemara rejects this:] Perhaps this inference applies only to the case of a koreh, (? female pheasant) , which normally rests upon the eggs of other birds. Since this is its normal behavior, one is obligated to send it away even if it rests upon the eggs of another kosher bird. This may not be the case with regard to a tasil or pigeon.

Let’s try and figure all this out. First, what are the identities of these three birds mentioned: the yonah, the tasil and the koreh?

Male and Female Bird Plumage

The Yonah is fairly easy to identify; there is unanimous agreement that it a dove. Or a pigeon. Confused? They are both members of the species Columbida: The common (or domestic) pigeon is Columba livia domestica, and the mourning dove is Columbidae Zenaida macroura. Moving right along.

The Tasil is a bit more challenging. Rashi declares that it is “a tahor [ie kosher] bird, similar to the yona.” And that’s how it is translated in the Schottenstein Talmud. Marcus Jastrow wrote in his dictionary that is “a species of small dove.” The Koren notes that the tasil might be “a bird similar to a pigeon, or to a laughing dove, a small dove native to Eretz Yisrael.” So a bit of a mystery.

The identity of the Koreh seems to be easy. At least that what it seems from the translations. The Soncino translates it as a partridge, as is does the Schottenstein. The Koren English translation is even more specific: “This bird is identified as the sand partridge, a desert bird of the genus Ammoperdix in the pheasant family Phasiandae.” Wow. That’s some impressive ornithology.

Actually that specific identification is very important, because there is a debate as to whether this whole business of sending away the bird brooding over some eggs applies only to the female bird, and not to a male that is incubating. Here is a photo of a male sand partridge. It is grey with wavy flanks and beautiful white markings over the beak and behind the eyes. The female is a drab sandy brown color.

Male sand partridge. Note the beautiful white markings behind the eyes.

Male sand partridge. Note the beautiful white markings behind the eyes.

A lady sand partridge. No white facial markings.

A lady sand partridge. No white facial markings.


According to the Talmud there is agreement that the command of shiluach haken does not apply to male birds. But there is a dispute about this specific bird, the koreh - our sand partridge. Rabbi Eliezer ruled that when it comes to this particular species, the male bird that is brooding must be frightened away before taking the eggs, just like the female.

תניא נמי הכי זכר דעלמא פטור קורא זכר ר"א מחייב וחכמים פוטרין

With regard to a male bird in general, one is exempt from the mitzva of sending it away, but with regard to a male koreh, Rabbi Eliezer deems one obligated to send it away from the nest, and the Rabbis deem one exempt from sending it away.

This requirement only makes sense if the two are readily distinguishable at a distance, and thanks to these nice photos, we now know they are.

By the way, have you wondered why this bird is called the קורא - koreh, which from the hebrew root ק–ר–א, k-r-h which means to call out? Apparently the bird has a prominent call which is heard long before it can be seen. Which perhaps gave its name: “the one that calls out.” (If you want to hear that call, click here. To be honest, to me it sounds like a slower version of the swish of a baby’s heartbeat heard with ultrasound. But that’s just me.)

Who is sitting on the eggs? Mom or dad?

As we noted, the Talmud rules that the commandment of shiluah haken applies only to the female of the species. Should the father be incubating, no such command applies (except for the sand partridge, as we just discussed). Here, for example, is what the great Maimonides wrote in his code, the Mishneh Torah:

רמב’ם משנה תורה הל׳ שחיטה. יג:י

זָכָר שֶׁמְּצָאוֹ רוֹבֵץ עַל הַקֵּן פָּטוּר מִלְּשַׁלֵּחַ

If a male was found incubating in the nest, there is no obligation to send him away [before taking the eggs or chicks].

This is also the ruling of the Shulchan Aruch, the Code of Jewish Law. Which raises the question - just how common is it for the male of the species to incubate the eggs? This is, of course a very challenging question to answer, because it all depends: which birds (European, American, African)? Birds of prey? Backyard birds? But given that, can we make a generalization?

Yale’s Ornithologist-in-Chief to the rescue

For an answer, Talmudology turned to Richard Prum, who is both the William Robertson Coe Professor of Ornithology in the Department of Ecology & Evolutionary Biology at Yale University, and the Curator of Ornithology, (and Head Curator of Vertebrate Zoology,) at Yale’s Peabody Museum of Natural History, in New Haven, Connecticut. And here is what he told us:

The brooding behavior of birds has evolved extensively among birds of the world. About 38% of bird species have female only incubation. About 50% of bird species have male and female incubation, and 6% of bird species have male only incubation.

This certainly came as a bit of a surprise. It turns out then that you will find a male brooding in the nest a lot of the time! Prof. Prum also noted that these behaviors are not randomly distributed among birds. Closely related species of birds tend to have similar incubation behavior, but higher groups may differ extensively. 

In addition, most of the species with substantial eggs have female only incubation. These groups include most game birds and waterfowl like chickens, quail, francolins, guineafowl, ducks, geese, etc. In most of these species, the male takes no part in parental care.  That last bit is really important, because it is just these kinds of kosher wild birds that are subject to the law of sending the mother-bird away. In most of these species the male takes no part. So the Talmud was spot on, so to speak, in limiting the commandment to these kinds of fowl. But there is another complication. Prof. Prum also wrote that “in many species with shared incubation, it is impossible to distinguish the male from the female by plumage.”

reasons For the Commandments

There is a well-known philosophical debate about whether it is appropriate to give reasons behind the 613 mitzvot (commandments) found in the Torah. Much has been written and many fine minds were engaged with this question as it pertains to the commandment of shiluach haken. Perhaps it is an example of imitatio dei:God is kind, so you should be kind to his creatures. Therefore send the mother bird away so she cannot get upset when you remove her eggs. As an example of this train of thought (and there are many) here is the commentary of the famous Moshe ben Nachman, (1194-1270), better known as the Ramban:

הטעם לבלתי היות לנו לב אכזרי ולא נרחם, או שלא יתיר הכתוב לעשות השחתה לעקור  המין, אע"פ שהתיר השחיטה במין ההוא. והנה ההורג האם והבנים ביום אחד, או לוקח אותם בהיות להם דרור לעוף, כאלו יכרית המין ההוא

If the nest of a bird chances to be in front of you: Also this commandment is explained by "it and its son do not slaughter on one day" (Leviticus 22:28); since the reason in both of them is that we should not have a cruel heart and [then] not have mercy, or that the verse should not permit us to be destructive to destroy the species, even though it allowed slaughter within that species. And behold, one who kills the mother and the children on one day or takes them when they are 'free to fly' is as if he cuts off that species.

A similar reason is cited by the French French commentator Rashbam Samuel ben Meir (1085 – c. 1158). It it prevents cruelty (שדומה לאכזריות ורעבתנות). So too the Spanish commentator R. Bechayei (1255-1340):

שלח תשלח את האם, טעם המצוה ללמדנו על מדת הרחמנות, ושנתרחק מן האכזריות שהיא תכונה רעה בנפש, וכעניין שאסרה תורה (ויקרא כב) לשחוט אותו ואת בנו ביום אחד, וכעניין שנצטוינו בתורה שבעל פה דרך רחמנות לא דרך אכזריות בשחיטה בצואר ולא מן העורף, והוא דעת הרב בספר המורה, וכבר הזכרתיו למעלה" 

The reason for the command is to teach us the quality of mercy, and to distance us from cruelty…just as the Torah prohibited the slaughter of a mother and its calf on the same day…

Maimonides, in his Guide for the Perpexled, also weighed in on the reason for this command, and decided it was all about kindness:

Guide to the Perplexed, Vol. 3 chap 48:

The same reason applies to the law which enjoins that we should let the mother fly away when we take the young. The eggs over which the bird sits, and the young that are in need of their mother, are generally unfit for food, and when the mother is sent away she does not see the taking of her young ones, and does not feel any pain. In most cases, however, this commandment will cause man to leave the whole nest untouched, because [the young or the eggs], which he is allowed to take, are, as a rule, unfit for food. If the Law provides that such grief should not be caused to cattle or birds, how much more careful must we be that we should not cause grief to our fellowmen.

On the other hand…

There are a few sources that criticize the entire enterprise of ascribing reasons for any of the commandments in general, and of shiluach haken in particular. Like this one in the Mishnah itself:

ברכות לג,ב

משנה :האומר על קן ציפור יגיעו רחמיך …משתקין אותו

If a person adds in his prayers: “Your mercy is extended to a bird’s nest, so too extend Your mercy to us…he is silenced

Why such drastic action for reciting such a nice prayer? Here is the talmudic discussion:

פליגי בה תרי אמוראי במערבא רבי יוסי בר אבין ורבי יוסי בר זבידא חד אמר מפני שמטיל קנאה במעשה בראשית וחד אמר מפני שעושה מדותיו של הקדוש ברוך הוא רחמים ואינן אלא גזרות

Two amora’im in Eretz Yisrael disputed this question; Rabbi Yosei bar Avin and Rabbi Yosei bar Zevida; one said that this was because he engenders jealousy among God’s creations, [as it appears as though he is protesting the fact that the Lord favored one creature over all others]. And one said that this was because he transforms the attributes of the Holy One, Blessed be He, into expressions of mercy, when they are nothing but decrees of the King that must be fulfilled without inquiring into the reasons behind them.

So there are two opinions as to why this prayer is forbidden: the first, because it is inherently unfair to single out the incubating bird for a dose of extra divine mercy. What about the rest of the animal kingdom? And the second, because in general, the commands have nothing to do with mercy. They are just the commandments of God. And if they are kind, well that’s an added benefit; but even if they were cruel they are there to be obeyed.

Ornithology and today’s daf

Now back to the observations of Prof. Prum, and today’s page of Talmud. If it is indeed the case that:

1) male and female birds are often equally likely to be incubating and

2) in many species with shared incubation, it is impossible to distinguish the male from the female and

3) that male incubators are exempt from commandment of shiluach haken,

then what becomes of the school of thought that ascribes mercy to the reason for it in the first place? Don’t male incubators, who have built the nest and are just as invested in the project as are the females, don’t they deserve some mercy too? And why exempt male birds when male and females are so often indistinguishable?

There is increasing evidence that all kinds of animals experience emotions just like we do. And it’s not only playful chimps and depressed dogs. Elephants mourn. Pigs kept in boring pens show behavior that in humans we would call depression. Rats enjoy being tickled.

And birds? Well, some birds like to surf at the beach, a behaviour that does not “seem to provide any obvious function apart from enjoyment — they look like they are having fun.” And birds have self-control. Really. Remember the Marshmallow test? (We reviewed it back in April 2015 when we learned Ketuvot 83. If you’ve forgotten, read this and then come back….) Well it turns out that when a (particularly smart and cooperative) parrot was given the bird equivalent of the test, he was successful 90% of the time, enduring delays of up to 15 minutes. The researchers noted that to do this “the parrot had to postpone the immediate available reward to gain more desirable future rewards, maintaining the choice to delay, and tolerate the frustration of this self-inflicted delay.” So, yeah, birds have self control. The more we study, the more we realize that animals too, have emotions. So if sending away the mother bird might reduce her grieving, let’s do it.

Pairs of bluebirds in my backyard, getting ready to build their nest, visit every empty nestbox, hoping in and out multiple times, the male alternating with the female...After weeks of scouting, the male puts a few branches or grass sems into one of the boxes, then lets the female guard the actual nest, while he guards the site. The drawn out decision process has reached its conclusion. Do bluebirds have free will?
— Frans de Waal. Mama's Last Hug: Animal emotions and what they tell us about ourselves. W.H. Norton 2019. p222
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