The common map turtle tends to bask during the middle of the day, and often does so in groups (2) (4) (5) (7). It is very easily startled, and if one member of a basking group is disturbed and moves away, the others will quickly follow (4) (7). This kind of behaviour is observed among most of the turtles of the genus Graptemys (7). Females tend to bask in larger numbers than males and more closely together, sometimes piled on top of one another (2) (4). This is possibly so that they can react more quickly as a group to a perceived threat (2) (4).
The body temperature of the common map turtle is controlled through basking in the summer months and hibernating throughout the winter (4). Common map turtles have been found to uptake oxygen via their skin. This means that they are able to remain in the water for weeks on end and can gain the vital oxygen that they require during hibernation (8).
Annual movements are seen in both male and female common map turtles, possibly to find new nesting and basking sites (4) (7), although summer basking sites are thought to remain the same from year to year (5). These movements are often a series of short distances, less that one kilometre a day, and males move a greater distance, on average, than females (4) (5) (7).
The common map turtle mostly forages for food during the day, in the morning and mid-afternoon (2), and leaves the middle of the day for basking (2). The common map turtle has specialised broad, flat jaws for feeding on molluscs, such as snails and clams, but it is known to feed on insects, crayfish and fish carrion as well (4) (5) (7). Vegetation makes up a small part of its diet (5), and food is always swallowed underwater (4).
Common map turtles mate twice a year, or more, in the spring and in the autumn (2) (5). Average clutches usually contain around 9 to17 eggs (2). The sex of the developing embryos is determined by the incubation temperature (4) (5), as is the case with most species of turtle (6). The emergence of the hatchlings from the nest seems to depend on the nest location, with some emerging in the autumn, and others after winter (2) (9). The nests are generally found in open areas of light soil or sand (2) (5) (7).
Turtle nests in general are predated upon by a range of vertebrates, and this is also the case for the common map turtle (2) (9). Eggs and juveniles have been known to be eaten by racoons, skunks, foxes, otters and rice rats (2) (5). Hatchlings are particularly vulnerable to attacks from birds such as gulls and crows (5). Adult females are at risk of predation when leaving the water to lay their eggs (2) (9), being taken by species such as coyotes (2) (5) (9).
There is very little known about when the common map turtle reaches sexual maturity (2) (5) (9). However, it is thought that females do not mate until they are 19 centimetres in length and around 14 years old (2) (5), while males are thought to mature after 4 to 6 years (5).
The common map turtle is thought to live for up to 20 years in the wild. It does not generally thrive in captivity, but one adult lived to an age of 18 years at Brookfield Zoo, Chicago (9).