In the Fall, it is often difficult to ID birds, as the adults lose their breeding costumes and the juveniles may look totally different. Often the male juvies resemble the female adults and don't get their male feathers until one or a few years later. Following are three comparison images of juvenile and adult Black-crowned Night Herons. In this case, I believe that the males and females are quite alike.
Top Image: Adult taken at 500 mm (Dx). Note the deep red eyes and no streaking on its chest and belly.
A juvenile about to transform to an adult, taken at 700 mm (Dx). Note the pinkish eyes and the minor streaking still evident on its chest.
This year's crop, taken at 500 mm (Dx). A juvinile , still fully streaked and with yellow eyes.
