Bird Sex ID

We have all struggled to ID the sex of various birds. Sometimes it is easy as either the male or female is brightly colored, smaller, or has some other very distinguishing characteristic. But when the phenotype of both male and female are identical, the process of determining sex gets much more difficult.
I have found that a bird’s sex can sometimes be distinguished by their behavior. With a little practice, almost any biologist can become proficient in this manner. Look at the picture below and see if you can identify the male and female bird in the picture.