SGL#166 Beaverdam Wetland

On a rainy Sunday afternoon in early October, my husband Bruce and I joined fellow members of our Juniata Valley Audubon Society on a field trip to SGL#166.

This 11,776-acre game land includes the Beaverdam Wetland Biological Diversity Area (BDA), which is tucked in a remote wooded valley in southern Blair County between Canoe and Brush mountains and forms the headwaters of Canoe Creek. And it lives up to its name because beavers still occupy the creek and wetlands.

Since Beaverdam Road is only open during big game seasons to a parking lot four miles from the game land’s southern boundary, we had a reasonably short hike on the gravel road to reach the Beaverdam area.

The rain stopped when we started off through a diverse upland hardwood forest that includes such trees as American basswood, sugar maple, and white oak, as well as limestone-loving yellow or chinquapin oak and the thicket-forming shrub or small tree American bladdernut that favors moist, floodplain forests and stream banks.

From the road I saw invasive stiltgrass and garlic mustard and occasionally a fern understory, but according to the Beaverdam Wetland BDA report, this forest also contains the usual invasive multiflora rose, Japanese barberry, and European privet as well as the native spicebush and black haw shrubs. We also stopped to admire a young American chestnut tree, a patch of partridgeberry and a winterberry, covered with red berries.

The BDA report lists a wide variety of spring wildflowers in the forest such as blue cohosh, wild ginger, jack-in-the-pulpit, mayapples, false Solomon’s seal, yellow fairy bells, and sweet cicely.

We were in, what I later learned from Justin Vreeland, Regional Wildlife Management Supervisor for the Southcentral Region of the Pennsylvania Game Commission, is the Canoe Creek Old Forest Unit (OFU), a 3,922-acre portion of the game land managed for late-successional forest attributes.

In addition to protecting the Canoe Creek riparian zone, it is hoped that this contiguous tract of mature hardwood forest will attract many forest-interior and riparian birds of conservation interest including Acadian flycatchers, blackburnian, black-throated green, black-throated blue, worm-eating, Kentucky and cerulean warblers, Louisiana waterthrushes, red-shouldered and broad-winged hawks, scarlet tanagers, wood thrushes, and yellow-throated vireos.

During our visit our bird list was meager—gray catbird, blue jay, eastern towhee, field sparrow and ruby-crowned kinglet—due to the weather and because most of the previously mentioned forest birds were already on their way south for the winter.

Once we reached the wetland complex with beaver ponds on either side of the road, the trees and shrubs changed to what the BDA report describes as “a mosaic of graminoid [grassy] meadow, shrubland and palustrine [wetland] forest communities.” The BDA report adds that “the floodplain holds an especially interesting palustrine woodland with a high diversity of plant species,” such as poison sumac, royal, interrupted and marsh ferns, white turtlehead, yellow marsh marigold, five sedge and two grass species.

We saw the shrub buttonbush and the vine virgin’s-bower, both wetland species, as well as thickets of alder. The bark of the latter is sometimes eaten by beavers, although they prefer aspens above all, followed to a lesser degree by willows, but they will eat the bark of other tree species if neither aspen nor willow are available. In spring and summer months, they switch to non-woody vegetation especially grasses and aquatic plants.

For instance, a study in Mississippi found in the stomachs of beavers material from 42 tree species, 36 genera of green plants, four kinds of woody vines and a lump of grasses, according to Ben Goldfarb in his engaging book Eager, the Surprising Secret Life of Beaver and Why They Matter. He writes that “beavers are among our closest ecological and technological kin” because both humans and beavers are “wildly creative tool users who settle near water, share a fondness for elaborate infrastructure, and favor fertile valley bottoms carved by low-gradient rivers.”

Before Europeans arrived in North America, researchers calculated that the continent had between 15 and 250 million beaver ponds. “The Lehigh River,” Goldfarb writes, was “almost choked with beaver dams, which helped form the ‘Great Swamp’ at its headwaters…” Beavers still change the landscape and by doing that create prime songbird habitat.

In another study in coastal Maryland back in 2000, researchers found that a single beaver pond slashed the discharge of total nitrogen by 18%, phosphorus by 21%, and total suspended solids—waterborne particles classified as a pollutant by the Clean Water Act—by 27%.

These clever engineers build their dams for safety from predators—black bears and coyotes in our area—shelter from weather, and food storage. Propelled in water by their webbed feet, they can hold their breath for 15 minutes, have transparent eyelids that allow them to see underwater, and a second set of fur-lined lips behind their upper and lower chisel-shaped teeth, that enable them to chew and drag wood without drowning.

Beaver fur consists of two-inch-long coarse guard hairs over a soft, thick, buoyant and waterproof underfur. A Scrabble-letter-sized patch of it has as much as 126,000 individual hairs, more than we have on our heads. Their flat, scaly tails are rudders and alarm systems and they have a net of tightly meshed blood vessels that can regulate their temperature.

They fell trees by balancing on their back legs with their tails beneath their bodies, and use their large teeth to chip away at the trunk until the tree falls. Then they gnaw off the branches and cut the trunk into manageable pieces before hauling them off to their building site. Researchers report that 62% of the trees beavers cut fall in the direction of the dam they are building. They peel their lodge or dam sticks and eat the inner bark before weaving them into their constructions.

The dams they build can be as small as a couple feet to half-mile-long dikes. A family unit of between four and ten consisting of mating adults, newborn kits, and yearlings can build and keep up more than 12 dams and change a narrow stream into a broad chain of ponds. They also construct burrows and lodges where they sleep, raise kits and winter. Since they don’t hibernate the adults spend the winter dragging sticks and roots from their submerged larder to feed their family.

Needless to say, we didn’t see any beavers during our field trip. Vreeland hopes to develop higher-quality beaver habitat along Canoe Creek by planting aspens.

There have always been beavers in this valley, although trees were first cut as early as 1807-1809 and into the 1870s to fuel Canoe and Etna iron furnaces. A lumber railroad operated in the upper Canoe Creek watershed and mining railroads along the southern ridge.

Since that time, at least one lumber company early in the twentieth century “turned [the valley] from a splendid forest to a desert waste,” according to outdoor writer and hunter, Harry P. Hays, who frequented the valley then. He also visited Margaret Aurandt, whose grandfather, John Hancuff, was the first settler in the valley in the early nineteenth century.

Aurandt was born in 1866 and lived in the valley most of her life, the last 17 years—from 1912 to 1929— alone and on her own, “her friends the trees, birds, flowers, animals, and other things of the forest. Her home stood at the edge of a magnificent stand of white pine trees, where the mid-day sun could only send scattered shafts of gold.” The logging “was a great blow to the lonely woman, who grieved deeply, and was bereft of much of the former joy of her woodland life,” Hays writes.

One hundred years have passed since the logging occurred. I think Aurandt would be pleased to learn of the establishment of the Canoe Creek Old Forest Unit, which Vreeland hopes will benefit many mature-forest-dependent species including a wide variety of birds such as northern goshawks, wild turkeys, and winter wrens, as well as mammals—fishers, silver-haired bats, white-tailed deer, black bears, gray and southern flying squirrels.

Furthermore, according to the comprehensive management plan for the OFU (shared by Mr. Vreeland), officials want to “promote late-successional forest conditions on higher quality soils.” Such forests “are rare because these historically were converted to agricultural land uses or subject to multiple timber harvests.” For this reason, large parts of the OFU are on good growing sites for both hardwood and conifer forests. The plan also calls for providing “an extensive area of unfragmented forest,” although it is now bisected by the game land’s road and a 100-meter-wide electric right-of-way corridor.

Still, the OFU is unique in southcentral Pennsylvania, and Vreeland says in an email, “I firmly believe if we are to conserve wildlife diversity, we need to maintain forests, to include areas largely left to nature’s processes, on an array of soil types, including productive ones, because these will produce different structural and compositional characteristics than a similarly aged forest on poorer soils.”