Bog Turtle
Glyptemys muhlenbergii

* Federal Threatened State Endangered *

Common Name:

Bog Turtle

Scientific Name:

Glyptemys muhlenbergii

Etymology:

Genus:

Giypt is Greek meaning "carved", emys is Greek meaning "turtle".

Species:

muhlenbergii - was assigned to honor Reverend Gotthilf Heinrich Ernst Muhlenberg, an 18th century botanist from Pennsylvania who first found this turtle in his millpond.

Average Length:

3 - 3.5 in. (7.5 - 9 cm)

Virginia Record Length:

4 in. (10.2 cm)

Record length:

4.5 in. (11.4 cm)


Virginia Wildlife Action Plan Rating Tier I - Critical Conservation Need - Faces an extremely high risk of extinction or extirpation. Populations of these species are at critically low levels, facing immediate threat(s), or occur within an extremely limited range. Intense and immediate management action is needed.

PHYSICAL DESCRIPTION: This is a small freshwater turtle that has a maximum carapace length of 115 mm (4.5 inches), and an average of 80-105 mm. The plastron length is from 71-92 mm. In Va., max known carapace length is 102 mm, maximum plastron length is 89 mm, and max body weight is 132 grams. The surface of the carapace is roughened with growth annuli, black to brown sometimes with irregular markings, and a smooth posterior rim. The keel is low in juveniles but often worn smooth with age. The centers of the pleural scutes may be lighter than the surrounding area. The marginals and bridge are colored like the carapace; 12/12 marginals, 4/4 pleurals, 5 vertebrals. The hingeless plastron is usually black with irregularly-shaped blotches of yellow to cream along the midline. The skin on the head, neck, and limbs is brown to pink, possibly with red mottling on the limbs. A large, conspicuous, orange, yellow, or red blotch lies behind each eye. The adult males have a concave plastron and an elongate tail base that places the anal opening beyond the carapacial margin (avg. precloacal distance = 24.8+/-5.0 mm, 16-31, n=12). The adult females have a flattened plastron, a higher and wider carapace, and a shorter tail (avg. precloacal distance = 14.4+/-3.5 mm, 11-18, n=5). The adult males can grow up to 105 mm or more in carapace length, and the adult females seldom grow larger than 100 mm. Virginia males are 70.2-101.7 mm carapace length (avg.=91.3+/-8.0, n=17), 63-88.7 mm plastron length, (avg. = 79.0+/-6.2, n=17), and weigh 54-132 grams (avg. = 106.1+/- 25.0, n=12). Females are 72.3-102.0 mm carapace length (avg. =87.3+/-7.5, n=15), 66.8-87.8 mm plastron length (avg.=108.2+/-19.7, n=11). Sexual dimorphism index based on carapace length is 1.05 *10760*. The juveniles have a slightly different pattern than adults. The carapace is more cylindrical and is brown, and the plastron is yellow with a large dark blotch in the center. The patch behind the eye is present at hatching. Hatchlings from Virginia were 27.7-28.5 mm carapace length (avg. = 28.1, n=3) *10760*.

REPRODUCTION: This species is sexually mature at 6 years of age. It breeds from late April-early June, in shallow water or on land. During mating the male clings tightly to the edge of the female's carapace and juxtaposes his tail beneath hers. There is no shell pounding. There may be two clutches a year of 3-5 eggs/clutch. Incubation takes 50-59 days. They average 30 X 16 mm. Shallow nests are dug in grassy or mossy areas or where there are soft soils. There may not be a formal nest dug, but instead the eggs are layed in the top of sedge tussocks. Most hatching occurs in August, but the young in some nests do not emerge until early October or the following April or May. The size at maturity is 70 mm plastron length *9286*.

BEHAVIOR: This species is active only during April, May, June and September and aestivates during high temperature. In the late spring, and late summer, they are active during the day only *2988,3072,3071,3076*. Activity shifts from midday and afternoon in early spring to morning in late spring and summer. The median home range size is between .06-.35 ha *11394*. Dispersion is random. They range over 3 acres or .0047 square miles *3074*. Basking occurs during the midday usually on grass mats or shallow rivulets. The body temperatures of basking turtles in PA were measured at 22.0-31.0 degrees C *10760*. More activity occurs during cloudy days than on bright sunny days. Bog turtles are basically omnivores and have been known to eat the following: a variety of insects (including beetles), earthworms, slugs, snails, millipedes, crayfish, tadpoles, duckweed, seeds of pondweed (Potamogeton sp.) and sedges (Carex sp.), blackberries and strawberries *10760,11613*. This species is non-territorial *9286*. When spooked a bog turtle may dive head first into the soft mud *10760*.

ORIGIN: The origin of this species is native *2988*.

POPULATION PARAMETERS: Most populations are composed predominately of adults, although the juveniles are very secretive. The adult sex ratio is usually 1:1. Growth rates decline with age and adults grew 1.7-4.0 mm per year *9286,10760*. The population size seems always to be small, usually 50-150 individuals site.

AQUATIC/TERRESTRIAL ASSOCIATIONS: Outside Virginia, this species is associated with Clemmys guttata and G. insculpta *2988,3071,3076,11613*. Alder (Alnus serrulata), skunk cabbage (Symplocarpus foetidus), and sedges (Carex sp.) are common plant associates. This species is preyed on by raccoons, skunks, opossum, dogs, and some wading birds. Adults are often found with missing toes and limbs, stubbed tails, and gnawed shells *9286,11613*. Bog turtles often burrow into mud or hide in grass tussocks. Their habitat is one of the last stages of wetlands succession, so turtles must eventually move to other sites or perish as drying occurs *3075*. Habitat loss due to drainage of freshwater marsh areas is the most serious threat to the isolated populations *9286,11613*.

References for Life History

  • 1012 - Gourley, E.V., Linzey, D.W. (Ed.), 1979, Bog turtle from the Proceedings of the Symposium on Endangered and Threatened Plants and Animals of Virginia, pg. 405-406,, 665 pp. pgs., Ext. Div., VA Tech, Blacksburg, VA
  • 2988 - Ernst, C.H., R.W. Barbour, 1972, Turtles of the United States, 347 pgs., Univ. Press of Kentucky, Lexington
  • 3071 - Arndt, R.G., 1977, Notes on the natural history of the bog turtle, .uc Clemmys muhlenbergi .us (Schoepff), in Delaware, Chesapeake Sci., Vol. 18, Num. 1, pg. 67-76
  • 3072 - Barton, A.J., J.W. Price, 1955, Our knowledge of the bog turtle, .us Clemmys muhlenbergi, .us surveyed and documented, Copeia, Vol. 1955, Num. 3, pg. 159-165
  • 3074 - Ernst, C.H., 1977, Biological notes on the bog turtle, Herpetological, Vol. 33, Num. 2, pg. 241-246
  • 3075 - Ernst, C.H., R.B. Bury, 1977, .us Clemmys muhlenbergi .us (Schoepff), Catalog American amphibians and reptiles, pg. 204-1-204
  • 3076 - Holub, R.J., 1977, The bog turtle, .us Clemmys muhlenbergi .us - a natural history, Herpetol. Bull. New York Soc., Vol. 13, Num. 3, pg. 9-23
  • 9286 - Terwilliger, K.T., 1991, Virginia's endangered species: Proceedings of a symposium. Coordinated by the Virginia Dept. of Game and Inland Fisheries, Nongame and Endangered Species Program, 672 pp. pgs., McDonald and Woodward Publ. Comp., Blacksburg, VA
  • 10760 - Mitchell, J. C., 1994, The Reptiles of Virginia, 352 pgs., Smithsonian Institution Press, Washington, DC
  • 11394 - Carter, Shawn L., Carola A. Haas, Joseph C. Mitchell, 1999, Home Range and Habitat Selection of Bog Turtles in Southwestern Virginia, J. of Wildl. Manage., Vol. 63, Num. 3, pg. 853-860
  • 11613 Pinder, M., 2001, Personal Communication, Expert Review for GAP Analysis Project, Va. Dept. of Game & Inland Fisheries

Photos:

*Click on a thumbnail for a larger version.


Verified County/City Occurrence

Carroll County
Floyd County
Franklin County
Grayson County
Patrick County
Roanoke County
Verified in 6 Counties/Cities.



FROGS

Virginia is home to 28 species of frogs and toads.

SALAMANDERS

We have a large diversity of salamanders consisting of 56 different species and subspecies.

LIZARDS

Virginia is home to 9 native lizard species and two introduced species, the Mediterranean Gecko and the Italian Wall Lizard.

SNAKES

The Commonwealth is home to 34 species and subspecies of snake. Only 3 species are venomous.

TURTLES

Virginia has 25 species and subspecies of turtle. Five of these species are sea turtle.