The northern map turtle (''Graptemys geographica''), also known as the common map turtle, is an aquatic turtle in the family

Emydidae Emydidae (Latin ''emys'' (freshwater tortoise) + Ancient Greek εἶδος (''eîdos'', “appearance, resemblance”)) is a family of testudines (turtles) that includes close to 50 species in 10 genera. Members of this family are commonly calle ...

. It is endemic to

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

Description

The northern map turtle gets both its common and scientific names from the markings on its

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

, which resemble contour lines on a map or chart.: Status Report of the Northern Map Turtle
Committee on the Status of Endangered Wildlife in Canada 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 Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

; males are in carapace length and weigh between , while females are in carapace length and weigh around . Females have a much wider head than males and this is associated with differences in feeding.Ernst, C.H., and J.E. Lovich. (2009). ''Turtles of the United States and Canada.'' 2nd Edition. Washington: Smithsonian Institution Press. (''Graptemys geographica'', pp. 293–302.) 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 long. Northern Map Turtle, plastron

Distribution

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. It also occurs in the

Susquehanna River The Susquehanna River (; Lenape: Siskëwahane) is a major river located in the Mid-Atlantic region of the United States, overlapping between the lower Northeast and the Upland South. At long, it is the longest river on the East Coast of the ...

system in Pennsylvania and Maryland and the

Delaware River The Delaware River is a major river in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. From the meeting of its branches in Hancock (village), New York, Hancock, New York, the river flows for along the borders of N ...

. 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''.

Habitat

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 but are more likely to live in smaller rocky rivers and

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

s in the south and west. Since they are turtles, naturally they need the sun to survive. Northern Map Turtle, sunning

Ecology and behaviour

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. Hibernacula must be well oxygenated because, unlike some other turtle species such as

painted turtle The painted turtle (''Chrysemys picta'') is the most widespread native turtle of North America. It lives in slow-moving fresh waters, from southern Canada to northern Mexico, and from the Atlantic to the Pacific. They have been shown to prefer l ...

s, map turtles need to absorb oxygen from the water to survive the winter. 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.

Reproduction

Northern map turtles

breed A breed is a specific group of domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist several slig ...

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 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 , incubation produces a majority of males, whereas yields more females.

Diet

Map turtle ''Graptemys'' is a genus of freshwater turtles containing 14 species, commonly known as map turtles. Crother, B. I. (editor) (2017). Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, with Comments ...

s are more carnivorous than most other members of the family Emydidae, and the northern map turtle is no exception. 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 Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...

. Adult males are much smaller and have narrower heads and feed on smaller molluscs and insects. Like most other aquatic turtles, feeding always takes place in the water. In places where

invasive Invasive may refer to: *Invasive (medical) procedure *Invasive species *Invasive observation, especially in reference to surveillance *Invasively progressive spread of disease from one organ in the body to another, especially in reference to cancer ...

molluscs such as zebra mussels and Asian clams (''

Corbicula fluminea ''Corbicula fluminea'' is a species of freshwater clam native to eastern Asia which has become a successful invasive species throughout North America, South America, and Europe. ''Corbicula fluminea'' is commonly known in the west as the Asian cl ...

'') are abundant, they may become the most important food of female northern map turtles.

Existing protection and conservation status

Map turtles are considered habitat specialists and may be replaced by a more tolerant species when their habitat is altered. 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. 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. This species has classified as least concern by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

United States

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.

Canada

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.Northern map turtle
Species at Risk Public Registry

References

External links

Northern Map Turtle
Illinois Natural History Survey
Common Map Turtle
Reptiles and Amphibians of Iowa

Savannah River Ecological Laboratory {{Authority control Graptemys Turtles of North America Reptiles of the United States Reptiles of Ontario Fauna of the Eastern United States Fauna of the Great Lakes region (North America) Least concern biota of North America Least concern biota of the United States Reptiles described in 1817 pl:Żółw ostrogrzbiety