Photo by John Hess

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Scanning the water’s edge for signs of aquatic life along the banks of the North Shore Channel or along the rocky edges of Northwestern University’s lagoon in summer, it is not uncommon to find a motionless and well-camouflaged Green Heron patiently fishing. It may be stretched out silently on a branch, intently staring into the water, or it may be stalking slowly along water’s edge. If it is startled, it will take off with slow wingbeats, with, as “Cornell Birds of North America Online” describes, “a scolding squawk and a stream of white defecation, giving it such vernacular monikers as “fly-up-the-creek,” “shite-polk,” and “chalk-line.”

This stocky wading bird about the same size as a crow weighs in at just about a half pound and is the smallest of the herons. It is adorned in an exquisite combination of colors of the natural world and mimics its background so effectively that it can hide in plain sight. Some shorebirds, young birds, females, and birds that forage on the ground are typically cloaked in styles that resemble a log or other natural feature. Stripes, colors, streaks, patches, variety all help to conceal them. The Green Heron assumes a hunched-over posture, neck hidden and standing stock-still, making it all but invisible. Slowly scanning the water’s rim with binoculars may reward the careful observer.

The Latin virescens means “green or verdant,” but the Green Heron is a multi-colored beauty: dark green (almost black) crown, yellow partial eye-glasses (particularly visible on juveniles), white throat and cheeks, russet neck and breast grading into a grayish belly, dark iridescent green-blue-black back and wings, sometimes tipped with buff half-moons, yellow legs, and a heavy dagger-like two-toned bill (black on top, yellow on the bottom) for grasping or piercing fish. When the Green Heron stretches its neck, as it often does when courting, or to break off a branch, defend its nest, or greet its mate when changing guard during early incubation, white and chestnut striping is visible along the underside of its neck. When excited, the Green Heron raises its dark crest. In breeding plumage, its bill becomes glossy black and its legs bright red or orange. Sexes are similar. Jeffrey A. Gordon, president of the American Birding Association, wrote, after proclaiming the Green Heron 2015’s Bird of the Year, “But get a good look in good light at a Green Heron in good plumage – when you can really see the interplay between the emeralds and magentas and buffs and yellows and lilacs – and they are easily among the most beautiful colored of their beautiful family, absolutely eclipsing most of the competition.”

The Green Heron is a carnivore. It feeds day or night, favoring small fish, but also eating crayfish, snakes, mice and dragonflies among other invertebrates. The Green Heron is one of the world’s few tool-using birds. It will cleverly create a fishing lure of a bread crust, insect, earthworm, twig, or even a feather and dangle it onto the water’s surface to entice prey.

The North American Green Heron is related to herons around the world. For a period of time, and thus in some field guides that are not current, its common name was the green-backed heron, but the name has been changed back to the original. The relationship of the North American species and others worldwide is not completely understood.

Some Green Herons are non-migratory and live permanently in the South. Those that migrate to Chicago may winter on the southern coast of the U.S. or in Venezuela or Colombia. They arrive in the Evanston area in late April, after flying in groups of their own and other species, usually at night. Males and females arrive together, customarily pairing up on the trip. Without evidence to the contrary, scientists consider them seasonally monogamous. They are known to breed in Jackson and Douglas Parks and North Pond in Chicago, but it would not be surprising to find them nesting along the North Shore Channel where they hang out during the day.

Male courtship displays are varied and energetic and include, among others, a Flying Around Display near breeding sites, calling from posts, and a Flap Flight Display “where the male lurches through the air with exaggerated flapping, producing whoom-whoom-whoom sounds, neck crooked, legs dangling, skowing, crest, neck, and scapular feathers erect, sometimes giving roo-roo calls before landing.” (Cornell)

The male selects the nest site, which may be an old nest, and starts construction. The female continues the work and the male provides twigs. The birds continuously refurbish nests during use. Nests can be solitary or in small colonies, usually near or over water in crotches of strong branches. They can be substantial affairs or so flimsy that eggs and young can be seen through the bottom. They often nest near grackles who, being very noisy, conveniently provide warning signs of intruders. An average Green Heron clutch is four eggs. Male and female both incubate the eggs, which hatch after 20 days. The nestling stage is about 15 days. The young stay near the nest after fledging. The young may become independent after 25 days, but the timing of independence and dispersal from the nest is little understood.

As one author says, Green Herons are common but not ordinary. Search out these beautiful and fascinating birds this summer before they begin their fall migration south in late September.

Libby Hill

Libby Hill is the author of "The Chicago River: a Natural and Unnatural History. She has been writing about birds and trees and Evanston's natural history for the Roundtable since 2004.