Every day, during the hottest months of summer, 19 workers labored to remove woody vegetation that has invaded a 5-acre wetland in Carroll County, MD. These workers are not your typical Fish and Wildlife staff. They're goats, and their affinity for woody vegetation make them superb partners in restoring this wet meadow, which is critical habitat for the federally threatened bog turtle (Clemmys muhlenbergii).
Bog turtles are known to occur in Cecil, Harford, Baltimore and Carroll counties of Maryland. Besides illegal collection for the pet trade, the primary threat to bog turtles is loss of the wetlands on which they depend. Saturated, spring-fed wetlands such as bogs, fens, wet meadows, sedge marshes and pastures with soft muddy areas provide the habitat these turtles require for feeding, breeding and hibernation. Development, shifts in land use, woody succession and the encroachment of invasive plants all contribute to loss of bog turtle habitat.
It has been hypothesized that, prior to settlement by Europeans, bog turtle wetlands were grazed by large herbivores such as bison, which helped to maintain the open canopy and pockets of muddy substrate.
Over the last century, the abundance of bog turtles in pastured wetlands indicates that grazing has been instrumental in maintaining the openness of wetlands needed for habitat. In the absence of grazing, most shallow wetlands give way to woody vegetation or dense thickets of exotic invasive plants like multiflora rose (Rosa multiflora). Restoration of these overgrown wetlands typically required labor intensive removal of vegetation using physical, mechanical and chemical treatment.
Some bog turtle wetlands have been overgrazed, so restoration work included stream fencing, pasture management and creating other water resources for livestock.
In 1997, the New Jersey Division of Fish and Wildlife's Endangered and Nongame Species Program began to experiment with livestock grazing to control woody vegetation in bog turtle wetlands. Since then, prescribed grazing has been successful in bog turtle sites in North Carolina, Georgia, Virginia, New Jersey, New York and Pennsylvania.
Cattle are most adept to graze on and control grasses. But goats-woody vegetation specialists-were selected to control the young red maple (Acer rubrum) trees and mutliflora rose threatening the open canopy and delicate wetland ecosystem required by bog turtles.
In 2007, the Maryland Department of Natural Resources, in partnership with U.S. Fish and Wildlife Service Chesapeake Bay Field Office, Maryland Cooperative Extension Service and Natural Resources Conservation Service, experimented with prescribed grazing on two wetland sites which did not contain any bog turtles at the time but did show records of bog turtles from the 1990s either at or close to the sites.
When the goats were introduced, there was a significant reduction in multiflora rose and red maple saplings at both sites. There was even an obvious browse line cause by the goats.
The next year, Fish and Wildlife Service biologists decided to try prescribed grazing at a known bog turtle site. Because of the goats' small size and their ability to escape enclosures, six-strand, high-tensile electric fencing was installed in the winter of 2008 and a run in shelter was built.
The goats were placed on the wetland site in July 19 and grazed on the vegetation until Sept. 19. They grazed on multiflora rose, Russian olive (Elaeagnus angustifolia) and red maple working their way from the upland/wetland edge inward. The goats will probably be used for at least another year, maybe two.
Nine photo monitoring stations were established, and photos were taken approximately every two weeks. Five vegetation plots were established and data characterizing vegetation cover will be collected. If this proves to be effective, goats may be used on other bog turtle wetland sites as a low-impact approach to control unwanted woody trees and invasive plants.
More than 97 percent of bog turtle wetlands occur on private lands, so the recovery of this species depends heavily on private landowners. Since 1997, various habitat restoration techniques have been completed at 17 wetlands on private lands in Maryland totaling more than 150 acres.
In addition to private landowners, partners include the U.S. Fish and Wildlife Service, Natural Resource Conservation Service, and Environmental Defense. The U.S. Department of Agriculture holds a permanent easement for the wetland portion of this property.