A yearly migration about to begin in Iowa may remind you of an old movie. Buzzards. Vultures. They’re a big bird with a bad image, honed by years ofcowboy movies and the image of a big ugly raptor that likes it when it cansee dead things. And there’s a good reason why they circle slowly in groups.According to Polk County naturalist Joe Boyles, it’s aeronautical, notpsychological, as the birds are riding “thermals” of warmer air. A yearlymigration is about to begin in Iowa, though you may not miss the birds whenthese have gone. The turkey vultures will be heading south, and you’ll knowif that’s what you’re watching. Boyles says the vultures are first-cousin toour national bird, the bald eagle, but even bigger. The big buzzards areabout to begin their fall migration OUT of Iowa. They have to go southbecause they smell their food and can’t find it that way when things arefrozen. The birds are native to most of the 48 continental states.