Bog turtle (Glyptemys muhlenbergii)
|Size||Length: up to 11.4 cm (2)|
The bog turtle is classified as Critically Endangered (CR) on the IUCN Red List (1) and listed on Appendix I of CITES (3).
Easily identifiable by the bright yellow, orange or red blotch on each side of the head (4), the bog turtle is a very small turtle with a light brown to black shell (2). Each bony plate that makes up the slightly elongated shell usually has a light centre (2). When young, the shell of the bog turtle has a rough texture, but this is worn almost entirely smooth with age, the result of much burrowing (4). The shell on the underside of the turtle (the plastron) is dark brown to black with a few irregular light markings, while the skin on all the other parts of the body is brown, sometimes streaked or speckled with a little red or orange (2). Male bog turtles differ in appearance from females by their longer, thicker tails and their concave plastron, while females have a wider and more domed shell (2).
The bog turtle occurs only in the United States, where it has a discontinuous distribution in twelve eastern states (5). A northern population occurs from western Massachusetts, Connecticut, and eastern New York southward through eastern Pennsylvania and New Jersey to northern Delaware and Maryland, while a southern population is found from southwestern Virginia, North Carolina, Tennessee and South Carolina to northern Georgia (2) (5). Isolated populations have also been reported from western Pennsylvania and in northwestern New York (5).
As its name suggests, the bog turtle is an inhabitant of marshy areas such as swamps, sphagnum bogs and marshy meadows, as well as slow-moving streams (1) (2) (6). It can be found in these habitats from sea level to elevations of over 1,200 metres (2).
Like many cold-blooded reptiles, the bog turtle is active only during the warmer parts of the day. It emerges from its night-time shelter and basks for some time in the sun before commencing its search for food (2). This semi-aquatic turtle forages both on land and underwater (2). Its highly varied and omnivorous diet consists primarily of insects, such as beetles, millipedes, dragonflies, and ants, but it also feeds on snails, slugs, earthworms and spiders (5), and even frogs, nestling birds, mice and voles. Berries, seeds, and other plant parts comprise the vegetarian part of its diet (2).
Mating takes place from March until June, and begins with a male searching out a female, identifying her sex by using sight and smell. Whilst circling the female, the male probes her tail and cloacal area with his nose, and may bite at her head and neck. The female may move away, resulting in a chase, with the male biting at her legs and head to stop her. Finally, the male will mount the female, accompanied by more bites to the head and neck, and mating lasts for 5 to 20 minutes (2).
The bog turtle lays eggs in June and July (2), usually in the late afternoon or early evening (5). The single clutch of one to six white eggs are laid either into a cavity dug by the female, or under moss or grass tussocks (2). The eggs hatch in August or September, and while most hatchlings emerge from the nest immediately, some may remain in the nest over winter (2). Both the eggs and hatchlings are preyed upon by a number of birds and mammals, including foxes, raccoons, and opossum (4).
In October (4), the bog turtle retreats into areas of dense vegetation to hibernate (5). Resting in soft mud, often just below a frozen surface, in the old burrow of a muskrat or meadow vole, amongst rocks, roots or under vegetation (5), the bog turtle will remain in hibernation until April (4). As well as burrowing for hibernation, this proficient digger will quickly burrow into the muddy ground whenever it is alarmed (2).
The bog turtle faces numerous potential threats, but the most significant and damaging is the loss, alteration and fragmentation of its wetland habitat. Many areas are being drained, dredged, filled or flooded, for urban development, agriculture, and pond and reservoir construction (4) (5). The loss and alteration of suitable habitat increases the risk of bog turtles being killed on roads, and leaves them more exposed to predation (5). The impact of this habitat loss on bog turtle populations is being compounded by the illegal wildlife trade (5), as unfortunately the small size, unique colouration and rarity of this turtle makes it highly valued in the pet trade (4).
Bog turtles are legally protected or regulated in nearly all states in which they occur (2), but most of these regulations relate just to the species and do not provide protection to its habitat (5). However, many states are increasing efforts to conserve both bog turtles and their habitat, and a number of wetland habitats containing turtle populations throughout the range are protected (5).
The bog turtle is also listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which means that international commercial trade in this species is prohibited (3). Yet despite this, and its legal protection at state level, illegal collection of the bog turtle remains a major threat due to very little on-the-ground enforcement of these laws (5). An effective law enforcement program, to cease the illegal trade in this Critically Endangered species, is a recommended and much needed conservation measure (5).
For further information on conservation of the bog turtle see:
Project Bog Turtle:
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- Cloacal: relating to the cloaca, a common cavity into which the reproductive, alimentary and urinary systems open.
- Hibernation: a winter survival strategy in which the animal passes the winter in a resting state. This period of inactivity is characterised by specific biological and biochemical changes including lowered blood pressure and respiration rate.
- Omnivorous: feeding on both plants and animals.
- Plastron: in reptiles, the lower shell of a turtle.
IUCN Red List (June, 2011)
- Ernst, C.H., Altenburg, R.G.M. and Barbour, R.W. (1997) Turtles of the World. ETI Information Systems Ltd, Netherlands.
CITES (June, 2008)
North Carolina Natural Heritage Program. (2001) Guide to Federally Listed Endangered and Threatened Species of North Carolina. North Carolina Department of Environment and Natural Resources, Raleigh, North Carolina. Available at:
- US Fish and Wildlife Service. (2001) Bog Turtle (Clemmys muhlenbergii), Northern Population, Recovery Plan. Hadley, Massachusetts.
- Alderton, D. (2002) Turtles and Tortoises of the World. Facts on File Inc, New York.