The Roc, also known as the Rukh, is a stupendously gigantic bird of prey that comes out of Persian legends. It appears in texts around the 8th century CE, and is present in numerous Middle Eastern stories, atural histories, and sailors' tales, including the 1001 Nights. Sinbad's second voyage includes a run-in with a Roc.
Marco Polo, who wrote about these birds in his highly embellished travel log. He claimed that they were flying birds of prey with 48 foot wingspans, 24 foot long flight feathers, and eggs that measured almost 150 feet in circumference. It is unclear what Polo was actually trying to describe, as no bird of prey has ever come close to that size. (the largest bird of prey ever discovered went extinct 6 million years ago and it had a 25ft wingspan) Perhaps he had them confused with the Elephant Birds of Madagascar, though they were flightless and had no wingspan to speak of. Their eggs however, while not 150ft in circumference, could hold 2.5gallons of water which may have assisted in Marco Polo's embellishment.
Rocs are typically described as being white, with a resemblance to either eagles or vultures, depending on the source. Because they are so large, their meals consist of large prey! Rocs were said to capture entire elephants in their claws, killing them by dropping them on to rocks from high places. This is similar to methods employed by real life birds of prey. Vultures drop bones from high up to crack them and get the marrow. Eagles will capture large prey, such as this goat, and drag them off of cliffs. So once again, we've taken a look at a mythical creature based in some fact!