Wild Wildlife: Black-Crowned Night Herons

A visitor touring the outdoor bird exhibits at the zoo might be surprised to see very large, impressive-looking birds perching in the trees and flying freely above the enclosures. These are black-crowned night herons; apparently, these wild birds like nesting at the zoo, near the bird house. I’m not sure if it’s because the area makes them feel safe and at home or if they enjoy taunting the captive birds, or both, but there they are: present in large numbers (forty? Sixty? More?) and displaying none of the shyness I’ve seen in them in wilder places. They’re constantly contorting themselves in the trees, too, in order to grab and then wrench loose twigs (or even branches) that are the right size for their huge nests.

[a juvenile heron -
why are their eyes yellow while the adults' are red?]