From Spring 2018
By Tim Maret
Hannah Roos, graduate student, in the field. Photo courtesy of Tim Maret.
Reptiles and amphibians are vulnerable to extinction worldwide, mostly due to anthropogenic impacts. The eastern United States is home to one such species of reptile that is no stranger to the threat of extinction. The bog turtle (Glyptemys muhlenbergii) is one of the world’s rarest and smallest turtles. Southeastern Pennsylvania has a large population of bog turtles and therefore has great potential for facilitating recovery.
Bog turtles are habitat specialists that rely on early successional, emergent wetlands where sedges and low grasses dominate. Habitat destruction, fragmentation, and degradation threaten this species by eliminating wetlands and ways for turtles to travel between patches of suitable habitat making regional extirpation a reality. Development and soil disturbance often lead to the introduction of invasive species that threaten bog turtle habitat. Invasive vegetation like multiflora rose (Rosa multiflora), reed canary grass (Phalaris arundinacea), and common reed (Phragmites australis) can transform open-canopy fens into closed-canopy swamps eliminating the open conditions required by the bog turtle. These threats have earned the bog turtle the federally threatened status.
Juvenile bog turtles. Photo courtesy of Tim Maret.
The Natural Resource Conservation Service (NRCS) manages wetland easements to assist private landowners in preventing habitat degradation and restoring bog turtle habitat. Prescribed grazing is being considered as a potential management tool for slowing succession of woody species and preventing invasive vegetation from becoming dominant. In the past, bog turtle habitats were presumably exposed to large grazers such as bison or elk. Little is known, however, about the effects of domestic cattle grazing on the bog turtle, particularly in Pennsylvania. NRCS awarded a Cooperative Ecosystem Studies Unit (CESU) grant to Shippensburg University to investigate the effects of grazing on wetland vegetation and bog turtle habitat use and movements.
Last spring and summer, Dr. Tim Maret and graduate student Hannah Roos used radiotelemetry to track bog turtles at grazed and ungrazed sites in southeastern Pennsylvania in order to examine their home range and habitat use in response to grazing. They also measured vegetation composition and structure in grazed and ungrazed wetlands. Maret and Roos are presently gearing up to do the same in 2018. By studying the structural changes in vegetation and determining how these changes affect microhabitat use and movements in response to grazing, their research will help NRCS manage habitat to save the bog turtle and other species that share their habitat.