The bog turtle (Glyptemys muhlenbergii ) is a critically endangered species of semiaquatic turtle in the family Emydidae. The species is endemic to the eastern United States. It was first scientifically described in 1801 after an 18th-century survey of Pennsylvania. The smallest North American turtle, its carapace measures about 10 centimeters (4 in) long when fully grown. Although the bog turtle is similar in appearance to the painted or spotted turtles, its closest relative is actually the somewhat larger wood turtle. The bog turtle can be found from Vermont in the north, south to Georgia, and west to Ohio. Diurnal and secretive, it spends most of its time buried in mud and – during the winter months – in hibernation. The bog turtle is omnivorous, feeding mainly on small invertebrates. The bog turtle is the state reptile of New Jersey.
An adult bog turtle weighs 110 grams (3.9 oz) on average. Its skin and shell are typically dark brown, with a distinctive orange spot on each side of the neck. Considered threatened at the federal level, the bog turtle is protected under the United States' Endangered Species Act. Invasive plants and urban development have eradicated much of the bog turtle's habitat, substantially reducing its numbers. Demand for the bog turtle is high in the black market pet trade, partly because of its small size and unique characteristics. Various private projects have been undertaken in an attempt to reverse the decline in the turtle's population.
The bog turtle has a low reproduction rate; females lay one clutch per year, with an average of three eggs each. The young tend to grow rapidly, reaching sexual maturity between the ages of 4 and 10 years. Bog turtles live for an average of 20 to 30 years in the wild. Since 1973, the Bronx Zoo has successfully bred the bog turtle in captivity.
The Bog turtle is a critically endangered semiaquatic turtle native to the eastern United States. Its head is dark brown to black in color and there is a bright yellow, orange, or red spot on each side of its neck. The spot is often forked, facing posteriorly. The Bog turtle has a dark skin color with an orange-red wash on the inside of the legs of some individuals. The carapace is domed and rectangular in shape, and it tends to be narrower toward the head and wider toward the tail. The carapace often has easily identifiable rings on the rough scales or scutes. In some older individuals and those that burrow frequently in coarse substrates, the shell may be smooth. Although generally black, a chestnut sunburst pattern in each scute is sometimes present on the carapace. The belly of the shell, the plastron, is also a dark brown to black color with light marks present.
Bog turtles are found from Vermont in the north, south to Georgia, and west to Ohio. They prefer calcareous wetlands (areas containing lime), including meadows, bogs, marshes, and spring seeps, that have both wet and dry regions. Their habitat is often on the edge of woods. Bog turtles may occasionally visit cow pastures and areas near beaver dams.
Bog turtles are semiaquatic and can move both on land and in the water. They are primarily diurnal, active during the day, and sleeping at night. They wake in the early morning, bask until fully warm, and then begin their search for food. During colder days, Bog turtles spend much of their time in dense underbrush, underwater, or buried in mud. On warmer days, their activities include scavenging, mating (during early spring), and basking in the sunlight. However, during times of extreme heat, Bog turtles usually take shelter from the sun and occasionally may either estivate or occupy networks of tunnels filled with water. At night, they bury themselves in soft tunnels. Bog turtles feed only during the day, but rarely during the hottest hours, consuming their food on land or in the water. Late September to March or April is usually spent in hibernation, either alone or in small groups in spring seeps. These groups can contain up to 12 individuals and sometimes can include other species of turtles. Bog turtles try to find an area of dense soil, such as a strong root system, for protection during the dormant period. However, they may hibernate in other places such as the bottom of a tree, animal burrows, or empty spaces in the mud. Bog turtles emerge from hibernation when the air temperature is between 16 and 31 °C (61 and 88 °F).
Bog turtles are omnivorous creatures. They feed on aquatic plants (such as duckweed), seeds, berries, earthworms, snails, slugs, insects, other invertebrates, frogs, and other small vertebrates. Occasionally they may eat carrion.
Bog turtles breed in the spring after emerging from hibernation. In a single season, females may mate once, twice, or not at all, and males try to mate as many times as possible. Nesting usually takes place between April and July. The female digs a cavity in a dry, sunny area of a bog, and lays her eggs in a grass tussock or on sphagnum moss. Most eggs are laid in June. Pregnant females lay 1 to 6 eggs per clutch and produce one clutch per year. Typically, older females lay more eggs than younger ones. After the eggs are laid, they are incubated for 42 to 80 days. Hatchlings are about 2.5 centimeters (0.98 in) long when they emerge from their eggs, usually in late August or September. Females are slightly smaller at birth and tend to grow more slowly than males. Juveniles almost double in size in their first 4 years but do not become fully grown until 5 or 6 years old. Both the males and the females become reproductively mature when they reach between 8 and 11 years of age.
The major threat to Bog turtles is the loss of their native habitat which has resulted in the disappearance of 80 percent of the colonies that existed 30 years ago. The invasion of non-native plants into their habitat is a large threat to Bog turtles' survival. Such plants out-compete the native species in their habitat, thus reducing the amount of food and protection. The development of new neighborhoods and roadways obstructs Bog turtles' movement between wetlands, thus inhibiting the establishment of new colonies. Pesticides, runoff, and industrial discharge are all harmful to Bog turtles' habitat and food supply. Because of their rarity, Bog turtles are also in danger of illegal collection, often for the worldwide pet trade. The eggs are also vulnerable during the incubation period and often fall prey to mammals and birds. In addition, eggs may be jeopardized by flooding, frost, or various developmental problems.
According to the Defenders of Wildlife resource, the total population size of the Bog turtle ranges between 2,500 and 10,000 individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List.
