Sir Richard F. Burton's notes on the Rukh:
The older "roc." The word is Persian, with many meanings, e.g. a cheek (Lalla "Rookh"); a "rook" (hero) at chess; a rhinoceros. etc. The fable world-wide of the wundervogel is, as usual, founded upon fact : man remembers and combines but does not create. The Egyptian bennu (Ti-bennu = phoenix) may have been a reminiscence of gigantic perodactyls and other winged monsters. [n.b. Burton was writing in the 1880's, it is no longer believed that humans were alive when pterodactyls were.] From the Nile the legend fabled by these Oriental "putters out of five fore one" over spread the world and gave birth to the Eorosh of the Zend, whence the Persian "Simurgh" (= the thirty-fowl-like"), the "Bar Yuchre" of the Rabbis, the "Garuda" of the Hindus; the "Anka" ("longneck") of the Arabs; the Hathilinga bird, of Buddhagosha's Parables, which had the strength of five elephants; the Kerkes of the Turks; the Gryps of the Greeks; the Russian "Norka"; the sacred dragon of the Chinese; the Japanesse "Pheng" and "Kirni"; the "wise and ancient Bird" Which sits upon the ash-tree yggdrasil, and the dragons, griffins, basiliks, etc. of the Middle Ages. A second basis wanting only a super structure of exageration (M. Polo's Ruch had wing-feathers twelve paces long) would be teh huge birds but lately killed out. SIndbad may allude to the Aepyornus of madagascar, a gigantic ostrich whose egg contains 2.35 gallons. The late Herr Hildebrand discovered on the African coast, facing Madagascar, traces of another huge bird. Bochart (Hierozoicon ii. 854) notices the Avium Avis Ruch and taking the pulli was followed by lapidation on the part of the parent bird. A Persian illustration in Lane (ii. 90) shows the Rukh carry ing off three elephants in beak and pounces with the proportions of a hawk and field mice: and the Rukh hawking at an elephant is a favorite Persian subject. It is possible that the "Twelve Knights of the ROund Table" were the twelve Rukhs of Persian story. We need not go, with Faber, to the Cherubim which garded the Paradise-gate. The curious reader will consult Dr. H. H. Wilson's Essays, edited by my learned correspondent, Dr. Rost, Librarian of the Indian House, vol. i. pp. 192-3.vol. vi. pp. 16-17
"...the quill of a wing feather of a young Rukh, whilst yet in its egg and unhatched; and this quill was big enough to hold a goat-skin's of water, for it is said that the length of the Rukh-chick's wing, when he cometh forth of the egg, is a thousand fathoms."
The older "Roc" which may be written "Rukh" or "Rukhkh." Colonel Yule, the learned translator of Marco Polo, has shown that "Roc's" feathers were not uncommon curiosities in mediaeval ages; and holds that they were mostly fronds of the palm Raphia vinifera, which has the largest leaf in the vegetable kingdom and which the Moslems of Zanzibar call "Satan's date-tree." I need hard ly quote "Frate Cipolla and the Angel Gabriel's Feather" (Decameron vi. 10.)vol. v., p. 122.
...I may remind the reader that the O. Egyptian "Rokh," or "Rukh," by some written "Rekhit," whose ideograph is a mostroud bird with one claw raised, also denots pure wise Spirits, the Magi, &c. I know a man who derives from it our "rook"=beak and parson.vol. xii. p. 186.