Reference for Pesachim 4:7
מוֹשִׁיבִין שׁוֹבָכִין לַתַּרְנְגוֹלִים בְּאַרְבָּעָה עָשָׂר. וְתַרְנְגֹלֶת שֶׁבָּרְחָה, מַחֲזִירִין אוֹתָהּ לִמְקוֹמָהּ. וְאִם מֵתָה, מוֹשִׁיבִין אַחֶרֶת תַּחְתֶּיהָ. גּוֹרְפִין מִתַּחַת רַגְלֵי בְהֵמָה בְאַרְבָּעָה עָשָׂר, וּבַמּוֹעֵד מְסַלְּקִין לַצְּדָדִין. מוֹלִיכִין וּמְבִיאִין כֵּלִים מִבֵּית הָאֻמָּן, אַף עַל פִּי שֶׁאֵינָם לְצֹרֶךְ הַמּוֹעֵד:
It is permitted to set up chicken coops [for the hatching of chicks, ab initio] on the fourteenth. And if a hen ran away, she is returned to her place, [That is, if she ran away on chol hamoed. For if she ran away on the fourteenth — if it is permitted to set coops ab initio on the fourteenth, it is obviously permitted to return her. We must be speaking, then, of a hen that ran away on chol hamoed. And the instance must be one in which she had been sitting on the eggs three days before she ran away, so that the eggs are no longer fit for eating and are "a thing that will go lost" if she is not returned. Therefore,] if she dies, another is set in her place [so that the eggs not go lost]. (Dung) is flung out from under the legs of the beasts on the fourteenth. And on chol hamoed, [which is of greater sanctity], it is [not flung out but] moved to the side. Articles may be brought to and from the craftsman's house [on the fourteenth], even if not needed for the festival.