The fluid lines of the birds' necks have the potential to lead the viewer's eye up and right out of the composition. But the beaks of the birds are the visual save. Black, and curved back into the center of the picture, their form encourages our eyes to return to the composition, where we can revisit the rich color contrast and warmth of an afternoon at the zoo.
Cropping plays an important role, building relationship and interest in the picture. The original photo was much larger. The birds were only bit players in one scene from the aviary. Isolating the flamingoes, and cropping the edges of the picture close to their heads, changes their status. Now they dominate the composition. In the revised photograph the story is all about them.