I’m a full-fledged “craniac” now that I’ve spent four days awestruck at one of Earth’s most epic animal migrations — on, of all places, the wind-whistling prairies of central Nebraska. Every year — perhaps dating back eons — about 500,000 sandhill cranes roost along the Platte River, swooping down in spellbinding squadrons and resembling both prehistoric pterodactyls and the flying monkeys from “The Wizard of Oz.” Deeply stacked in shallow water and on sandbars, the cranes’ deafening cacophony will absolutely blow your mind — at times their nonstop racket sounded like raucous crowds cheering gladiators at Rome’s Coliseum. World-renowned anthropologist Jane Goodall, who has crane-watched here for 20 seasons, compares the feathered phenomena to the famed wildebeest migration in Africa.