Common map turtles are less tolerant to poor conditions than most other turtles (Kirkpatrick 1999). Humans are hurting the turtles by numerous methods. Pollution, waterfront development is destroying their breeding sites, and automobiles are also a killer of these turtles when they are migrating to the breeding sites (HSUS 1999). Fishing also has a negative affect on them, they get caught on the fishing hooks (Harding 1997). Populations have been reduced or eliminated in some areas, but they do still persist in suburban rivers and agricultural lands (Harding 1997).
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: no special status
These turtles are sometimes, rarely, used as food. The pet trade hasn't taken an interest in the common map turtle, probably due to the difficulty of maintaining them in captivity. They also don't affect the fishing industry, other than getting caught on the hooks, since they do not eat any of the game fish (Harding 1997).
Common map turtles are omnivores (Kirkpatrick 1999). The feeding always takes place in the water. The adult females, due to their large heads and strong jaws eat larger prey than the males. The females consume snails, clams, and crayfish. The males eat aquatic insects, snails, and smaller crustaceans. Both are also known to eat dead fish and some plant material (Harding 1997).
The Common map turtle inhabits an area from southern Quebec and northwestern Vermont where it lives in the St. Lawrence drainage. Its range extends west through the Great Lakes and into southern Wisconsin and eastern Minnesota, west of the Appalachians, south to Kansas, northeastern Oklahoma, Arkansas, Tennessee, Alabama and then northwestern Georgia. It also occurs in the Susquehanna River system located in Pennsylvania and Maryland and also in the Delaware River (HSUS 1999).
Biogeographic Regions: nearctic (Native )
Common map turtles inhabit ponds, river-bottoms and lakes. The abundance of aquatic vegetation is preferred (Kirkpatrick 1999). They prefer large bodies of water and areas with fallen trees and other debris for basking (Conant and Collins 1998).
Aquatic Biomes: rivers and streams
Average lifespan
Status: captivity: 5.5 years.
Length: females are 7 to 10.5 inches and males are 3.5 to 6.5 inches.
Common map turtles get their name from the markings on the carapace. The light markings resemble waterways on a map or chart (Conant and Collins 1998). The lines on the carapace are a shade of yellow or orange and are surrounded by dark borders. The rest of the carapace is olive or grayish brown. The markings on the older turtles may be barely visible because of darker pigment. The carapace is broad with moderately low keel. The hind of the carapace is slightly scalloped shaped due to the scutes (Harding 1997). The plastron of an adult map turtle tends to be plain yellowish color (Conant and Collins 1998). The head, neck and limbs are dark olive, brown or black with thin yellow, green or orangish stripes. There is also a oval spot located behind the eye of most specimens (Harding 1997). There is sexual dimorphism in size and shape. The females are much larger than the males. The males also have a more oval carapace with more distinct keel, narrower head, longer front claws, and a longer thicker tail. The males vent also opens beyond the edge of the carapace whereas the female's open up the carapace (Harding 1997). The young map turtles have a pronounced dorsal keel and patterns on the plastron consist of dark lines bordering the scutes (Conant and Collins 1998). A hatchling has rounded gray or grayish-brown carapace about 1 in long. The pattern is light circular markings. The stripes located on the head and limbs are just like the adults (Harding 1997).
Other Physical Features: ectothermic ; bilateral symmetry
Common map turtles breed in the spring and the fall. Most mating takes place in deep waters. The nesting period lasts from May to July. Unshaded sites with sandy soil is highly preferred (Harding 1997). The female usually chooses well-drained areas for depositing the eggs (Kirkpatrick 1999). The nest cavity is dug with the hind feet. The size of the clutch is between 6 to 20. The eggs are oval and have a flexible shell that is about 3.2 cm. After the eggs are laid the cavity is filled. They hatch between 50 to 70 days of incubation and most emerge in August or September. When a nest hatches late, the common map turtle has been known to overwinter in the nest (Harding 1997). The female usually lays two or multiple clutches in one breeding season. The sexes of the young are determined by the temperature. 25°C incubation will give majority of males whereas 30-35°C will yield more females (Kirkpatrick 1999).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate)
Average age at sexual or reproductive maturity (female)
Sex: female: 5110 days.
The northern map turtle (Graptemys geographica), also known as the common map turtle,[4] is an aquatic turtle in the family Emydidae. It is endemic to North America.
The northern map turtle gets both its common and scientific names from the markings on its carapace, which resemble contour lines on a map or chart.[5] These lines are usually shades of yellow, tan, or orange, and are surrounded by dark borders, with the rest of the carapace being olive or greyish brown. However, the carapace markings tend to fade as the animal matures, and in older individuals are usually only visible when the shell is wet. The carapace has a hydrodynamic appearance and is broad with a moderately low keel. The rear of the carapace is flared and the rear marginals form serrations. The plastron is yellowish and is marked by a central dark blotch (plastral figure) that follows the sutures of the plastral scutes and fades with age so that many adults lack a pattern all together (i.e., the plastron is immaculate). The head, neck, limbs and tail are dark green with thin yellow stripes, and an oval or triangular spot is located behind each eye. Like other map turtles, this species exhibits extreme sexual size dimorphism;[6] males are 10–16 cm (3.9–6.3 in) in carapace length and weigh between 150–400 g (5.3–14.1 oz), while females are 18–27 cm (7.1–10.6 in) in carapace length and weigh around 0.67–2.5 kg (1.5–5.5 lb). Females have a much wider head than males and this is associated with differences in feeding.[6] Males have a narrower carapace with more distinct keel, narrower head, and a longer, thicker tail. Unlike females, the opening of the cloaca is beyond the rear edge of the carapace. Young map turtles have a pronounced dorsal keel. Hatchlings have a round greyish-brown carapace that is about 2.5 cm (0.98 in) long.
Northern map turtles inhabit an area from south Quebec and Ontario to northern Vermont where it lives in the St. Lawrence River drainage basin. Its range extends west through the Great Lakes and into southern Wisconsin and eastern Minnesota, west of the Appalachians, south to Kansas and northwestern Georgia. A population has been found in Northeastern Mississippi.[7] It also occurs in the Susquehanna River system in Pennsylvania and Maryland and the Delaware River. Also, a small European population occurs in the Czech Republic, which was formed from escaped or released turtles and their descendants. In the Czech Republic, this turtle is considered an alien species, but is threatened together with Czech native turtles, other reptiles and amphibians by a large population of another invasive turtle, Trachemys scripta elegans.
The northern map turtle inhabits ponds, rivers, and lakes. They prefer large bodies of water and areas with fallen trees and other debris for basking. These turtles are more often found in rivers than in lakes or ponds. They are found in larger rivers and lakes in the northern portion of their range[8] but are more likely to live in smaller rocky rivers and streams in the south and west. Since they are turtles, naturally they need the sun to survive.[6]
This turtle is dormant November through April, depending on local climatic factors. Northern map turtles spend the winter under water and do not surface to breathe, especially when ice cover makes this impossible. Adults rest on the bottom or wedged underneath rocks or logs and often hibernate communally with other northern map turtles where they may remain somewhat active.[5] Hibernacula must be well oxygenated because, unlike some other turtle species such as painted turtles, map turtles need to absorb oxygen from the water to survive the winter.[6] They typically bask in groups and are diurnal, meaning they are active exclusively in daylight hours. Northern map turtles are also quite shy and difficult to approach; they usually slip into the water and hide at the first hint of danger.
Northern map turtles breed in the spring and fall. Most mating takes place in deep waters. The nesting period lasts from May to July. Unshaded sites with sandy soil are highly preferred. The female usually chooses well-drained areas for depositing the eggs. The nest cavity is dug with the hind feet. The size of the clutch is between six and 20. The eggs are oval, about 3.2 cm (1.3 in) long, and have a flexible shell. After the eggs are laid, the cavity is filled. They hatch after 50 to 70 days of incubation, and most hatchlings emerge in August to September. When a nest hatches late, the northern map turtle hatchlings have been known to overwinter in the nest. The female usually lays two or more clutches in one breeding season. The sexes of the young are determined by the temperature. At 25 °C (77 °F), incubation produces a majority of males, whereas 30 to 35 °C (86 to 95 °F) yields more females.
Map turtles are more carnivorous than most other members of the family Emydidae, and this includes the northern map turtle. Adult females have wide heads, strong jaws and broad alveolar crushing surfaces in their mouths which they use to feed on molluscs, their primary prey, as well as insects and crayfish.[6] Adult males are much smaller and have narrower heads and feed on smaller molluscs and insects.[6] Like most other aquatic turtles, feeding always takes place in the water. In places where invasive molluscs such as zebra mussels and Asian clams (Corbicula fluminea) are abundant, they may become the most important food of female northern map turtles.[9]
Map turtles are considered habitat specialists and may be replaced by a more tolerant species when their habitat is altered.[10] Unfortunately the effects of human interference by way boating and recreation on shorelines are likely impeding the map turtle from re-establishing itself in natural areas.[11] Thus, populations of Northern map turtles have probably declined across their entire natural range but they remain widespread and may be abundant in some locations.[6] The species is classified as least concern by the IUCN.
Collecting, keeping, and selling of northern map turtles is prohibited by Animals in Captivity regulations in nine states. It is considered endangered in Kansas, Kentucky, and Maryland.[12]
Like most jurisdictions of the United States, Canada lists northern map turtles as a species of special concern. This means that they are being threatened by something but are not yet endangered. They are being watched carefully.[13]
The northern map turtle (Graptemys geographica), also known as the common map turtle, is an aquatic turtle in the family Emydidae. It is endemic to North America.
