Midrash sur Zacharie 10:8

(Fol. 63) R. Juda said: "The comorant (Lev. 11, 17) is that bird which catches fish out of the sea; the hoopoe (Ib.) is that bird which has a double crest." We are also taught in a Baraitha to the same effect: The hoopoe is that bird which has a double crest, and it is the same bird which brought the worm shamir for the [building] of the Temple. R. Jochanan, upon seeing a comorant would recite the following verse (Ps. 36, 7) Thy judgments are like the great deep; and upon seeing an ant he would recite the beginning of that passage, Thy righteousness is like the mighty mountains. R. Juda said: "The gier-eagle (Lev. 11, 17) refers to the bird which produces the sound Sh'rakrak, and why is it called Racham [which means mercy]?" Said R. Jochanan: "Because as soon as the Rahcam (gier-eagle) appears, mercy comes upon the world." Said R. Bibi b. Abaye: "This refers only when it stands upon something and produces the sound Sh'rakrak, and we have a tradition that when she will sit upon the ground and pronounce that sound, then it be a sign for the Messianic period, as it is said (Zech. 10, 8) I will hiss (esh'rka) for them, and gather them." R. Ada b. R. Shimi said unto R. Idai: "Did it not happen that one of them were sitting on a cultivated field making the above sound when a stone fell upon it and pierced its brains [hence the sign is not positive]? "That one was a liar [and was therefore killed]," came the reply.