Five years ago, there were 13 nesting Great Blue Heron pairs in that single tree top. Most pairs fledged a chick or two each summer, but at least one nestling never made it. Juvenile mortality is high in birds; it’s the lucky chick born in any given spring that makes it to breeding adulthood.It’s an odd sight to watch a heron, looming heavy-winged in flight, come in to land in a leafy tree top. We think of herons as Florida residents, the kind of birds that wade in palm-lined ponds or strip-mall wetlands in some perpetually sunny, forever-humid habitat. But Great Blue Herons range widely, from southern Canada to northern South America, with western Pennsylvania right in the middle of their breeding range.
By the water’s edge, Great Blue Herons look as natural as can be, all spindly legs and gray-blue body, s-curved neck and a sharp, powerful bill, orange-yellow below, streaky black above. See a heron stab a fish and you’ll respect the thrust of that bill, quicker than the flashing fins now held aloft and quickly consumed. The Great Blue Heron is a watcher and a patient fisher, though it will take reptiles, amphibians, rodents and other birds for meals.
In our region, nestlings hatch in spring and spend the next warm months growing up on a steady diet from ponds, streams and rivers. Watch for the adult Great Blue Heron slowly flying across the hills in the morning toward water, then heading back hours later to feed the young by coughing up their morning catch. When one bird returns, the other often passes the parental duties off and launches out with a throaty, prehistoric “fraaakkk” call to feed itself and gorge for junior, too.
Hatchlings grow to adulthood with amazing speed. From an egg not much larger than a billiard ball, a Great Blue reaches almost four feet tall and over five pounds in a few months. When juveniles first take flight, their wingspan is about 72 inches, the same as the armspan of a person six feet tall. From a distance, a Great Blue Heron in flight can look like a Bald Eagle to the untrained eye; their wingspans are almost the same, but watch the rhythm of the actual wing beats. An eagle tends to soar on outstretched board-flat wings. By comparison, a Turkey Vulture has dihedral wings with a tippy, circling flight. The Great Blue Heron has deep, curved wingbeats, trailed by arrow-thin, outstretched legs in powerful, linear flight that make it easy to recognize with practice.
You’ll see these birds all summer, but watch for them next winter, too. I’ve seen them out of their woods, amassed on the island below the Highland Park Bridge, silent sentinels, just above the cold Allegheny as the ice flows by.