Perhaps it was the memory of a rainy April day at the Brucker Great Blue Heron Sanctuary of Thiel College, or perhaps it was my admiration for these elegant waterbirds and the chance to see them once again going about their familial tasks. Whatever the reason, I had volunteered to participate in a statewide survey of great blue heron colonies that the Pennsylvania Game Commission conducts every five years. I also persuaded my husband Bruce to serve as pilot and our son Dave as co-pilot of our northern expedition to check on two Clinton County heronries.
We chose last April 26–ornithologist/artist John James Audubon’s birthday–to check first on the Rosecrans Bog Natural Area colony in Bald Eagle State Forest. We had last seen that small heronry of 11 nests six years ago during a summer Pennsylvania Native Plant Society outing. At that time all of us had stayed far across the bog from it and watched quietly through binoculars, knowing that great blue herons are sensitive to disturbance near their nests.
I was eager to see the Rosecrans Bog colony again and following directions to the bog that Bruce had written for my book More Outbound Journeys in Pennsylvania, we reached Cranberry Road shortly after 9:00 a.m. To our surprise, it was gated and hostile signs claimed the road was private.
Bruce cracked open our Pennsylvania DeLorme Atlas and, after consulting it, he followed a maze of forest and back roads until he reached what appeared to be the closest public access. We parked the car and walked a succession of mostly uphill trails 1.8 miles to the bog.
The day was spectacular, bathed in the pastel shades of emerging tree leaves that glowed in the bright sunshine, so we didn’t mind the unexpected hike. Here and there the white of blooming shadbush lit up the understory and beside one rushing stream several hobblebush shrubs flowered. Occasional white birch trees dangled golden catkins that trembled in the breeze. Along the trail black-throated green and black-and-white warblers, ruby-crowned kinglets and blue-headed vireos sang and in the underbrush silent hermit thrushes raised and lowered their rufous tails.
When we reached the bog, we squished along its edge over sphagnum moss spangled with goldthread and the emerging leaves of Canada mayflower and fly poison. Canada geese called, red-winged blackbirds sang, and two pairs of wood ducks took off, protesting loudly. The bog looked almost the same as we remembered it, surrounded by a mixed hemlock-hardwoods forest, the open water punctuated by silvered tree snags. Those snags had held the herons’ nests. But a sad silence had fallen over the bog. There were no nests and neither sight nor sound of any great blue herons.
Great blue herons do abandon sites, especially if they are disturbed by humans in isolated areas. Perhaps sounds from nearby rural homes had bothered them. Since we were way behind schedule, we didn’t have much time to wonder where they had gone. Instead we quickly hiked back to our car and sat beside a tumbling stream to eat our lunch.
The bigger adventure lay ahead. All we had to go on was a brief description and point on a sketch map supplied by the folks who had checked out the site five years before. The so-called Lebo Run heronry of 13 nests existed in a remote beech, hemlock, and black cherry forest in Sproul State Forest. Bruce had carefully studied and measured the point against topographic maps of northern Clinton County and was confident he had pinpointed its location. After an hour’s drive over winding, back country roads, we reached a gravel forest road.
“Road closed 9.5 miles ahead, dead end,” the sign warned. It also should have said “Four-wheel-drive access only.” Fortunately, we were driving such a vehicle and Bruce had calculated that the colony was 7.5 miles away.
We pressed onward, creeping up a steep, narrow road with a several-hundred-foot drop-off and no guard rails. I spent my time staring in the opposite direction at the road bank covered with blooming long-spurred violets, spring beauties, wild geraniums, Canada mayflowers, mayapples, and mitrewort and hoping we would not meet an oncoming vehicle.
Finally, we reached the top of the mountain and drove for what seemed like miles, splashing through deepening potholes and trying to avoid the road crown that was too high even for our Pathfinder. The mostly hardwood forest had an understory of small hemlocks and white pines in some areas. Red maple trees shimmered with gold and red blossoms while red elderberry shrubs bloomed in the understory. Once we stopped to let a pair of ruffed grouse cross the road. Several times wild turkeys paraded past.
Then, off to our left, we noticed a large, recent timber cut, stoutly enclosed by solar-powered, five-strand, electric fencing. Bruce, who had been pausing frequently to check his calculations against trail markings, suddenly stopped the car, pointed to the fenced area, and said, “The heronry should be less than a quarter of a mile in that direction.”
A sign on the fence instructed hunters to hold up the bottom strand with a stick and crawl under.
“We’re hunters,” Dave argued. “We’re hunting for great blue herons.” He held the fence strand up for Bruce and me as we wriggled under, bellies flat on the muddy ground, and we did the same for him. With compass in hand, Bruce led the way through a maze of green-leaved fire cherry and two-year-old white pine seedlings.
Once again the area was eerily silent. All we heard was the sound of wind in the trees. We rolled under the fence on the far side of the cut and cast about for any sight or sound of herons. Then we sent Dave off to hike quickly for a mile in either direction in case Bruce had miscalculated. After half an hour, Dave returned with a stiff neck and nothing more.
Glumly we retraced our steps. This time we looked more closely at the size of the stumps left in the timber cut. Once Bruce stopped in the middle of it and said, “This is where I had calculated the colony was.” I remembered then that great blue heron colonies are protected only during their breeding period. Once the herons leave, in August, trees holding nests can be cut. Or possibly they could have gone elsewhere even before the logging. But studies have shown that road-building and logging within a third of a mile of a colony can cause herons to abandon their nests.
“Fool’s errand,” I kept thinking as we drove those long, rugged miles back down the mountain. How could we have lost two heronries in five years?
We weren’t the only volunteers who couldn’t find heronries. Out of approximately 83 known colonies in the late 1990s, 29 had disappeared. On the other hand, volunteers had discovered 15 new colonies and 36 old colonies had increased in size. Still, statewide there was a net loss of nests.
Great blue herons are not endangered species. But the loss of forested wetlands, their preferred nesting habitat, is a problem throughout the mid-Atlantic states. Human disturbance is another although it often depends when in their courtship and nesting cycle the disturbance occurs. Not only that, but some colonies react more strongly to disturbance than others.
Here in Pennsylvania great blue herons return in late February or early March. Although they will use the same site year after year, they usually choose a new mate and a new nest. The largest and heaviest of North American herons, they stand four feet tall, weigh between six and eight pounds, and have a seven-foot wingspan. More gray than blue, their white heads sport dashing black plumes. They have long, white, black and reddish-brown necks, golden, daggerlike bills, and greenish-brown legs. Both their bills and legs flush red during courtship and the skin between their eyes and bills turns lime green. They also come adorned with fresh, grayish-blue plumes that splay from their breasts and backs.
They put all this finery to good use during prolonged courtship displays that include bill snapping, neck stretching, wing preening, circle flights, crest raising, fluffed and arched necks, bill clappering, and bill duels. Throughout the colony, great blues fight over the sticks used to refurbish old nests and build new ones. All of this is, of course, a noisy process.
The male does most of the gathering of foot-long sticks which he breaks off from branches, picks up from the ground, or steals from neighboring nests. He presents his mate with the sticks and she places them in the nest–a platform of sticks, lined with pine needles, dry grass, moss, or small twigs, that is three to four feet in diameter and 30 to 40 inches across. The female lays two to six dull, pale blue eggs and both sexes incubate the eggs for 27 days. They spend another two months feeding and brooding their young, often flying 12 miles or more to find food for them. Great blue herons mostly eat fish, but they also take amphibians, insects, reptiles, mammals, crustaceans, and birds.
When the young herons are three months old, they explore the adjoining treetops by first hopping out of the nest and into nearby branches. Then they learn to use their bills as hooks and pull themselves farther from their nests, branch by branch. At four months of age they are on their own.
All the herons leave their colonies and most revert to their singular life of stalking, often belly-deep in the water of marshes, lakes, and rivers, in search of food. Most of Pennsylvania’s great blue herons leave the state by mid-October and spend their winters in the Caribbean or in Central America although some do remain here year-round.
Our largest colonies are in the glaciated northern corners of the state. Northwestern Mercer County holds the most nests. It was there that I sat mesmerized over a decade ago in a covered shelter at the Brucker Great Blue Heron Sanctuary of Thiel College and watched through my binoculars as the largest great blue heron colony then in Pennsylvania set up housekeeping for the year.
But it too disappeared. The 190-nest site was abandoned in 1997 and nobody knows why. But Ed Brucker, who had been studying the site since the mid-1970s, and Bob Ross, who helped him to save it from logging in the 1980s, are pretty sure where those herons went. At the time the Brucker heronry was abandoned, the nearby Barrows heronry, which is along the Little Shenango River, doubled in size. According to Ross, it is now the largest in the state, with over 400 nests, and may be one of the largest non-insular colonies in the northeast north of the Chesapeake Bay.
Great blues come and they go and I frequently see one fishing quietly along the Little Juniata River when I cross the bridge. The closest known heronry is in Rothrock State Forest near Greenwood Furnace State Park. Birder Greg Grove found it in 2000 when it contained four nests. Last year it had ten. Part of the colony is on an “island” formed by the East Branch Standing Stone Creek and all the nests are in tall white pines even though there are also tall hemlocks and deciduous trees in the forest.
Great blue herons don’t always nest in colonies so it is possible that the herons I see on the river have nested individually in some hidden, wetland forest. Wherever they come from, I am grateful for their regal beauty as they stand alertly in the water, waiting to stab a fish, but lifting off if I show an interest in stopping and watching them.