The night stalker

StoryImage( ‘/Images/Story//img-ZoMK0UxXDZ.jpg’, ‘Photo by Paul Crittenden’, ‘A black-crowned night heron surveys Horicon Marsh in southern Wisconsin for his next meal.’);

The black-crowned night heron is not entirely a bird of the night. During the daylight hours, it goes about its mundane activities, but when darkness falls it becomes a stalker-hunter, and joins the voices of the night with its loud and raucous quawks.

It is a heron that is easy to get to know because of its rather large size (23 to 28 inches), its almost universal distribution over North America, and the characteristic voice that may startle the listener the first time he hears it. There are undoubtedly some who know the night stalker only by ear and after dark, having never actually seen it.

This heron brings to mind a portion of “Paul Revere’s Ride” by Henry Wardsworth Longfellow: “…A voice in the darkness, a knock at the door, And a word that shall echo forevermore!..”

The black-crowned night heron is, to some extent, like Paul Revere. It does not knock on doors, but to many of our countrymen, it is a voice in the night that will long be remembered.

The night heron is a stocky bird with comparatively short neck and legs. The adult has distinctive coloring, with black cap and shoulders, gray wings, rump, and tail; and pale to gray underparts.The bill is stout and black, and the eyes are red. For most of the year, the legs of the adult are yellow-green, but during the breeding season they take on a pink color. The juvenile has a brown head, neck, and chest, and the belly is streaked with buff and white. The wings and back are darker brown, and the tips of the feathers sport large white spots.

It is believed that this heron developed the habit of feeding at night to avoid competition with the day-feeding great blue heron, which is much larger and more aggressive than the black-crowned. The great blue and some others occupy the same ecological niche as the night heron and have approximately the same diet.

The night heron’s food is made up largely of aquatic animals that can be grasped with the formidable beak. Fish, amphibians, crayfish, leeches, and mussels are preferred, but almost anything else that is organic will be eaten when the bird is hungry. They have been known to take rodents, lizards, insects, birds, eggs, carrion, plant material, and garbage from landfills. I once saw a black-crowned night heron perched on a tree limb along a river in Texas that had a rather large water snake in its beak. While the great blue and green herons stab their prey with their beaks, the night heron uses the beak to grasp its victuals. The other herons mainly stay in one place and let their prey come to them, but the night stalker moves around considerably while foraging for food.

A study was made of 50 meals of black-crowned herons and included the following items: 60 crayfish, 61 catfish, 31 other fish, and 79 dragonflies. Young herons were once hunted and eaten by some people, but this is rarely done today. The adults have never been considered edible.

The courtship ceremony among birds may be rather simple or elaborate. The night heron male employs a variety of highly structured resources to impress a potential mate: dancing, leg color change¸ sounds, plume erection, eyeball protrusion, and other antics. The first move the male makes is to lower his head and go into an odd sort of dance on the site of the future nest. While he is cavorting about, he emits sounds that resemble steam escaping from the safety valve on a boiler. His legs develop a bright rosy tinge while all of this is going on, and, if these tricks do not attract a suitable mate, he can protrude his eyeballs from their sockets and raise the feathers on the crown, neck and back. Males of other species having trouble seducing females might do well to take lessons from the male night stalker.

Populations of black-crowned night herons around the county appear to be stabilized or increased at the present time. Adults used to be trapped or shot around fish rearing sites, but other means to discourage them from eating the fish are now available. They are protected by federal migratory bird regulations. DDT and other chlorinated hydrocarbon type insecticides took their toll on heron populations because of their high rank in the food chain, but the use of these insecticides was banned in the early 1970s.

We are delighted that these interesting birds sometimes visit the two impoundments in the Gingerwood Section of Loves Park.

Dr. Robert Hedeen is a former resident of Maryland’s eastern shore and resided in the Chicago area from 1960 to 1971. He is a retired professor emeritus of biological sciences in the University of Maryland system. He has published more than 30 scientific papers, has written numerous magazine articles, and is the author of two books on the natural history of the Chesapeake Bay.

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