Our Better Nature: What Makes Great Blue Herons So Great?

Usually, “great” means either wonderful or huge. Not always. The Great Depression, for example, was hardly a picnic for folks back then, and Great Britain is nowhere near the biggest land mass on the globe. But the great blue heron (Ardea herodias), whose range includes all of the contiguous U.S. as well as southern Alaska, deserves to be called great. First, it’s the largest North American heron (we have ten native species). And whether on land or in flight, it’s one of the most picturesque and graceful birds one could ever hope to see.

Despite its name, the great blue heron is not cerulean or cobalt. At rest, most are light grey-blue, but their darker, slate-blue flight feathers are exposed when they take to the air. Though juveniles are entirely pale blue, adults sport an orange bill and a white crown with a dark head crest. To complicate things, some great blue herons are brownish, and one subspecies in Florida is white. Adults stand nearly five feet tall, and their wingspan can measure 6.5 feet across, but thanks to their hollow bones, they weigh just five to six pounds.

Great blues herons are year-round residents in the southern half of the United States and along the Pacific coast up to Alaska, but they nest as far north as northern Canada. In winter, some go south into Central America and parts of the Caribbean. In fact, they venture as far south as the Lesser Antilles.

One of the reasons they’re so widely distributed is that they are generalist feeders, which makes them highly adaptable. As a species of wading bird, great blues stand motionless in shallow water, waiting for a chance to spear a fish or frog with its bill in a lightning-fast strike. Other prey include insects, small mammals, and water birds. Great blues hunt mostly in freshwater environments, but are at home in saltwater marshes and tidal pools, too.

While their harpoon-bills are well-suited to hunting, these are also used affectionately during courtship. And, as you might expect, they’re great for protection.

In 1996, I became licensed by the New York State Department of Environmental Conservation as a Class I (beginner) Wildlife Rehabilitator. In the study guide for the exam, one item that caught my eye was a graphic of a heron stabbing someone in the eyeball. Yeah. The point was that you should cover an injured heron with a blanket before picking it up.

Great blue herons start breeding in their second year, and if they live to their species potential, might continue for another fifteen years. They are monogamous during each breeding season, but every spring, they get to play round-robin and pick a new partner.

The preferred heron nest location is high in a mature tree in a wetland, often a standing dead tree within a beaver pond. Being surrounded by a natural “moat” affords their eggs and babies some protection. Herons nest in groups, occasionally with hundreds of nests in a single colony. Apparently, the correct term is a heronry, though I had always called it a rookery. No matter what you call them, these nesting sites are impressive.

The coarse, unkempt nests of sticks are striking to behold, as big as four feet across and 3.5 feet deep. Generally, the nests are used year after year, getting refurbished every spring. Egg clutches vary from two to six eggs, with more in the far north to compensate for a lower chick-survival rate.

Since herons return to their nests by dusk, you can surmise the location of a heronry by watching the direction the adult takes. If you are fortunate enough to find a heronry, bring binoculars and keep your distance. You may be treated to the return ritual when adults (both males and females incubate eggs and feed the young) return to the nest.

Adults may touch bills with their mates in a show of affection before lovingly (I assume) barfing pre-digested fish and frog mush into the open beaks of their babies. I have seen the young waiting for Dad or Mom to come back with carry-in food, their beaks pointed upward and waving gently like some strange nest-grass blowing in the wind.

For many years, I lived on a beaver pond-studded piece of land in the St. Lawrence Valley of New York State. My property had two small heronries on separate ponds, and a few herons would wing by each evening near dark. If I was outside, they’d let out their alarm call, a guttural “gronk.” I’m not a bird linguist, so maybe it was “fronk,” or “bronk.” But herons have a broader repertoire of voices. They coo and cluck to each other on the nest, and clack their bills.

Even though great blue herons are big, weapon-wielding birds that surround themselves with water, they still fall prey to eagles, hawks, and great horned owls. Since herons are a top or near-top predator, they are also vulnerable to environmental toxins that get magnified at each level of the food chain. Human disturbance and habitat loss are other challenges faced by herons. In spite of everything, their population is currently stable or increasing slightly, depending on region.