Reptiles of North Carolina
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Emydidae Members:
NC Records

Glyptemys muhlenbergii - Bog Turtle

No image for this species.
Taxonomy
Class: Reptilia Order: Testudines Family: Emydidae Subfamily: Emydinae
Taxonomic Comments: As currently recognized (SSAR, 2016), the genus Glyptemys contains two eastern North American species, the Bog Turtle and Wood Turtle. Only the Bog Turtle occurs in North Carolina, with the Wood Turtle barely entering Virginia from the north. Previously, these species were included in Clemmys along with the Spotted Turtle and variously other members of the subfamily Emydinae.
Species Comments: Despite the highly fragmented range, no subspecies are recognized. Ernst and Lovich (2009) speculate that the now widely separated northern and southern populations were probably in genetic contact until European settlement greatly reduced and fragmented the range of this species.
Identification
Basis for Records: Photographs showing the orange blotch on the side of the head are sufficient to identify this species.
Description:
Field Marks: Bog Turtles are small and mostly dark brown in color, with a conspicuous orange or yellow blotch or blotches located behind the eye. The carapace is often uniform in color but the scutes may have irregular pale streaks (Palmer and Braswell, 1995). The skin is mostly brown, but there may be some marbling with yellow or orange.
Morphological Features: The carapace is narrowly ovoid and somewhat domed and keeled. The plastron is brown and lacks a hinge. Males are larger than females. In North Carolina, maximum carapace lengths are: 4" (103 mm), males and 4" (102 mm), females. Males have a concave plastron and longer and thicker tails; the vent located posterior to the rear edge of the shell.
Technical Reference: Palmer and Braswell (1995); Ernst and Lovich (2009)
Field Guide Descriptions: Beane et al. (2010); Powell et al. (2016)
Online Photos:    Google   iNaturalist   GBIF
Observation Methods: The secretive nature of this species, along with the dense herbaceous cover and mucky substrates of its habitats, make observation extremely difficult. Individuals are now often tagged with radio-transmitters, allowing researchers to locate them as needed.
Distribution in North Carolina
Distribution Comments: North Carolina populations are confined to the mountains and western Piedmont, with those along the borders of Virginia, Tennessee, Georgia, and Tennessee extending a short ways across the state lines. Nearly all of our populations are widely separated from one another, particularly in the Piedmont.
Distribution Reference: Palmer and Braswell (1995); NCMNS Herpetology Collection Database (accessed 2023-01)
County Map: Clicking on a county returns the records for the species in that county.
Key Habitat Requirements
Habitat: Bog Turtles occupy several types of mucky, usually well-insolated wetlands. These include true peatlands, wet pastures, sedge meadows, and at least one high elevation fen (Palmer and Braswell, 1995; Beane et al., 2010). In the Southeast, open, herb-dominated wetlands are naturally created by beaver ponds, which as they fill in with sediments support what were once known as "beaver meadows", i.e., wet meadow habitats dominated by sedges and other wetland graminoids and forbs. While fire may be partly responsible (along with renewed beaver activity) for maintaining the open, herbaceous character of these sites, beavers are the original creators and maintainers of these habitats. We hypothesize, therefore, that Bog Turtles, in our area at least, are primarily beaver-associated species.
Environmental and Physiological Tolerances: This is primarily a northern species, ranging as far north as Lake Ontario in northern New York state. It thus appears to be cold-hardy and may be limited to cooler areas in North Carolina, explaining its absence from the warmer eastern Piedmont and Coastal Plain.
Adaptations to Natural Disturbances: Bog Turtles were probably once associated with the sedge meadows that develop successionally as beaver ponds fill in. As such, it must have originally have needed to disperse along riparian corridors in order to keep up with changes in the availability of its ephemeral habitats. Whether it has lost some of its dispersal behavior, as have other beaver-associated species (e.g., Neonympha mitchellii) due to near extirpation of their habitat creator, appears to be unknown.
Biotic Relationships: Bog Turtles are omnivorous, feeding on a wide range of invertebrates, small vertebrates -- mainly insects and other arthropods -- and plants (see Ernst and Lovich, 2009, for a long list of food species). Prey are captured both in the water and on land. Diets appear to differ in different parts of its range. In turn, Bog Turtles are preyed upon by a wide range of other vertebrates, including Snapping Turtles, snakes, herons, Opossums, and Carnivores; raccoons may be the most important predator (Ernst and Lovich, 2009).
Life History and Autecology
General Ecology
Adverse Environmental Impacts
Habitat Loss: Draining, filling, and conversion of wetland habitats for agriculture, silvicuture, or development is undoubtedly responsible for the current reduced and highly fragmented state of Bog Turtle habitats and populations. The extirpation of beavers over most of eastern North America a century ago was another major and often under-appreciated contributor to the devastation of wetland habitats.
Habitat Fragmentation: Bog Turtles appear to require a metapopulation structure in order to survive within a given watershed. I.e., there must be a number of occupied sub-populations such that local extirpation of any one of them can be countered by re-colonization from those that survive. This strategy works, however, only where dispersal between the subpopulations can be accomplished. When habitat loss and degradation eliminates some subpopulation sites, it increases or essentially prevents the movements between subpopulation sites, leading, through attrition, to loss of all formerly inter-connected units. Bog Turtles appear to be exemplars of this type of attritional extirpation.
Interactions with Humans: Collection for the pet trade has been a major threat to the small populations of Bog Turtles that still exist in our landscape.
Status in North Carolina
NHP State Rank: S2
Global Rank: G2G3
Status in North Carolina: T
Global Status: T(S/A)
Status Comments: The Bog Turtle in North Carolina is regarded as highly fragile species. Our populations are currently protected under the federal Endangered Species Act due to their similarity in appearance to the populations in the Northeast, which receive full federal protection as Threatened Species. In North Carolina, they are also protected under state law as a Threatened Species, which mainly serves to prohibit any take except under special circumstances involved in scientific research or conservation, where permits have issued by the NC Wildlife Resources Commission.