you tell which is the male?
The bird on the left is the male. Do you notice clues in the two birds' sizes and coloration? The male is slightly larger than the female. Do you notice clues in the head positions of the two cranes? The male's head is thrown farther back than the female's head as they call.
While size and color clues are good for telling the gender of most birds, it doesn't always work with Whooping cranes. The only way to be certain of the gender is to examine their DNA. This can be done by a blood test and also by examining the lining of the shells from which the crane hatched as a chick.