Birding by Zipline
The Adventures on the Gorge Canopy Tour sits on two tracts of land, totaling about 40 acres—one property that had been purchased from a timber and mining company and another leased from an owner who, bound by a conservation easement, agreed not to cut trees as long as the tour exists. Ziplines can serve a valuable conservation purpose, too: As long as they’re financially viable, critical bird habitat can’t be logged. The two activities simply aren’t compatible.
"I’m going,” Linda says. But it’s not very convincing. “Okay,” she says again. “I’m going.” The zipline stretches 540 feet in front of her—more than twice as long as the previous ones—and we can’t see where it ends. Just as I begin to wonder what happens if she won’t go, she’s off. “Zipline clear,” Reed’s voice soon declares.
The platform Linda lands on is wrapped around a giant tulip poplar; the trunk, scarred with sapsucker holes, diverges into two broad leafy arteries. As with every tree on the course, the zipline is customized to the poplar’s particular quirks—and it’s carefully engineered not to cause any harm. Rather than passing through the tree itself, the cables are threaded through wooden blocks carved to fit the trunk’s surface. Compression holds the blocks to the tree. Over time, hardware is adjusted to allow the cables and the platform to expand with the tree’s girth. Guy wires connect each platform tree to others nearby; when a strong wind blows the entire course can sway gently, reducing stress on any individual tree.
On our next zip we pass from the deciduous forest to one dominated by hemlocks. We land on one that’s several hundred years old and covered with lichen. “How many of you know what HWA is?” Tiny asks. “It’s a little blue-headed vireo!” Linda interrupts, peering through her binoculars. The bird dances from the hemlock to a nearby tulip poplar and back. “We’re right by her nest,” Tiny says, pointing to a thicket of grass, hair, and twigs just uphill of the platform. Then he tries his speech again. “HWA is hemlock woolly adelgid, a two-millimeter-long insect that was imported from Japan,” he adds.
Since its discovery in Richmond in the 1950s, HWA has spread along the East Coast—it now infests 50 percent of the hemlock stands from Maine to Georgia. A sap-sucking insect, it feeds on the trees’ storage cells, which provide nutrients for the following year’s growth. In effect, HWA starves trees, and further insults like drought finish them off.
HWA can take out a tree like this one in two to four years, Tiny says. We look closer and realize some of its limbs look a bit gray and scraggly, and they’re missing needles. To treat trees foresters use one insecticide on the bark and another buried at the base of the tree. (The concentration required to kill adelgids is minute, and has no known effect on insectivorous birds.) Both chemicals are temporary and have to be reapplied every few years. They’re also expensive. A dollar of every zipline purchase—matched by Adventures on the Gorge—covers the costs of treating the hemlocks on the property.
“We have 4,500 trees that are six inches and bigger,” Tiny says. “So far we’ve treated the course trees, the guy wire trees, and some of the bigger and more spectacular trees in our forest—600 to 800 altogether.” This year the company will start on those with smaller diameters. The U.S. Forest Service is looking at longer-term solutions that could treat trees on a landscape level—as a forest, as opposed to one tree at a time. But the most promising techniques are still a few years away.
"There’s a hooded warbler over here,” Reed says, listening intently. Kim launches the iBird app on her phone and, in seconds, tawee-tawee-tawee-tee-o whistles clearly from its speakers. The song echoes back to us from the foliage. The response gets louder and louder until suddenly we see a flash of yellow and black. There’s a mad dash for the side of the platform nearest the bird. I say a silent prayer of thanks that we’re all clipped in. The warbler is in clear sight on the branch of a hemlock, framed by two poplars.
We’re still pleased with our technological prowess as we cross a footbridge—pausing to admire a phoebe hawking for insects over Mill Creek—and unclip from the cables for a short hike through the woods. After passing a wood thrush we reach the next platform: a large, flat piece of sandstone overlooking a small ravine. This zip is the longest of the course—730 feet—and starts by launching off a rock lodged in the ground. Reed goes first and reports over the radio: “It’s birdy over here.” Now Linda gets a running jump, pulls her legs up to get optimal speed, and shouts “Bombs away!” as she disappears into the trees, binoculars slung over her shoulder.
The four-foot-diameter hemlock on the other end of the cable towers above us. It was already 300 years old when Daniel Boone surveyed the area in the late 1700s, when this was still Virginia. There’s a good chance Washington passed it on his way to survey lands along the Kanawha and Ohio rivers. “Fast-forward to the Civil War,” Tiny tells us. “Two future U.S. presidents fought in this part of Fayette County. Robert E. Lee came—”
“Scarlet tanager!” Linda interjects. “Nobody saw it? It’s red!”
Kara’s skeptical. “Sure, it’s a scarlet tanager…” she says.