Before Pearl Harbor, before Brown v. Board of Education, before Rosa Parks sat down on that bus, there were the “Dumbo” crows, led by the bowler-hatted, cigar-chomping top bird, Jim Crow.When Dumbo the baby elephant first took flight in the 1941 Disney animated feature, he landed in a tree. Out on a limb, the black crows were there to greet him.Teasingly kind and mockingly helpful, these “boys,” as …