Over the past 12 summers, the night herons' original settlement has grown into a full-fledged rookery, hosting about 50 wild breeding pairs. With an abundance of food and safe nesting areas, the Detroit Zoo is a perfect breeding ground for the birds, according to Detroit Zoological Society Curator of Birds Tom Schneider.
"The herons just showed up here one year, were successful breeding, and have been coming back ever since," said Schneider. "Local birders are delighted to be able to see this elusive species at the Zoo."
The rookery is located behind the Sweet Treats concession across from the bear dens. Visitors know they are in the right place when they hear the distinct clicking calls the birds use to communicate with each other from the treetops.
The black-crowned night heron (Nycticorax nycticorax) is normally nocturnal, making it difficult to spot outside of the breeding season. During active nesting, which spans from May through July, daytime foraging is common and the birds can be observed flying to and from their rookery at the Detroit Zoo.
The night heron's head is crowned with black feathers that extend down its back and contrast against the light-grey feathers that cover the rest of its body. Its beak is black and eyes are crimson. During breeding season, the bird's legs change in color from yellow to pink, and two to three long white plumes extend down its neck.
The black-crowned night heron is classified as "special concern" by the Michigan Natural Features Inventory due to declining populations. The species is sensitive to wetland destruction and environmental contaminants.