Emydoidea blandingiiBlanding's Turtle

Geographic Range

Blanding's turtles (Emydoidea blandingii) are native to Canada, stretching as far west as southeastern Ontario and as far east as southern Nova Scotia. They continue southward to the United States. With a range including the Great Lakes region, these reptiles’ range stretches as far northeast as Maine and as far northwest as South Dakota and Nebraska, including southeastern New York, Pennsylvania, Illinois, Indiana, Iowa, Massachusetts, southern Michigan, southeastern Minnesota, New Hampshire, as well as Ohio. Blanding's turtle populations are greater in Wisconsin, Missouri, and north-central Nebraska, and disjunct populations are found in Nova Scotia, Massachusetts, New Hampshire, and New York. (Congdon, et al., 2008; van Dijk and Rhodin, 2016)

Habitat

Blanding’s turtles are semi-aquatic, living mostly in shallow wetland habitats where aquatic vegetation is abundant. These reptiles will specifically live in ephemeral wetlands in attempts to keep away from predators that are more prevalent in permanent wetlands. They will also utilize the grasslands next to their freshwater shelters for living, especially during the summer. During the overwintering period, these freshwater turtles are mostly found in places with less than a meter of water such as marshes, ponds, bogs, fens, and creeks. These wetland habitats will range from 35 to 105 centimeters in depth, and are very similar in the range of depth in their non-overwintering sites, ranging from 30 to 125 centimeters.

Female Blanding’s turtles require terrestrial nesting habitats where soil has little to no vegetation. The lack of vegetation means less food available and therefore fewer potential predators in the vicinity. They will build their nests on the sides of roads and also on edges of trails. For feeding and mating, Blanding’s turtles will move to temporary wetland habitats and swamps. Terrestrial habitats are also the most common living situation during the night.

Juvenile turtles are observed mostly in shallow waters adjacent to forested grounds. This habitat choice minimizes predator encounters as well as encounters with bigger turtles. (Congdon, et al., 2008; Edge, et al., 2009; Ernst and Barbour, 1992; Harding, 2000; Newton and Herman, 2009; Refsnider and Linck, 2012)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range depth
    0.30 to 1.25 m
    0.98 to 4.10 ft

Physical Description

The smooth carapace of Blanding’s turtles ranges from dark brown to black. These ectothermic reptiles have yellow spots on their dorsal shells. As adults, their plastrons have a variety of black and yellow patterns, the most common being yellow with black spots along the scutes. The shells of adult turtles can stretch from 150 to 240 millimeters. Weights range from 750 and 1400 grams. Their heads are flat and the dorsal and sides are bluish-gray. Their eyes protrude, while their snouts do not. Yellow scales can be seen on the legs and tails and they have webbed toes. Although there are no significant size differences between male and female Blanding’s turtles, male plastrons are usually more concave than those of females.

The hinges of the ventral shell are able to move at two years old in juveniles and can fully close when they reach five years. The plastrons of juveniles are black with yellowish tan coloring on the edges of the ventral shells. They have proportionally longer and thinner tails than adults. Juvenile turtles are also brighter in color on the carapaces than the adults. Hatchlings have more rounded shells that range from 29 to 39 millimeters and weigh anywhere between 6 and 10 grams.

Eastern box turtles (Terrapene carolina) are similar in appearance, but Blanding’s turtles are distinguished by the bright yellow color on the ventral portion of their throats and long necks with dark lines on the upper jaw area. Eastern box turtles only have yellow on their chins, but not their throats or necks. Blanding's turtles are also bigger than eastern box turtles. ("Blanding's turtle: Emydoidea blandingii", 2015; Congdon, et al., 2008; Ernst and Barbour, 1992; Harding, 2000)

  • Sexual Dimorphism
  • sexes shaped differently
  • Range mass
    750 to 1400 g
    26.43 to 49.34 oz
  • Range length
    150 to 240 mm
    5.91 to 9.45 in

Development

Like other turtles, Blanding's turtles exhibit temperature sex determination. Gutzke and Packard (1987) incubated eggs at 26.5 C and found that all males hatched, while all females hatched at 31 C. They hypothesized that all males would develop at temperatures less than about 28 C, and all females would develop at higher temperatures, above 30 C. These cut-off conform to standard temperature cut-off for most turtle species. Time to hatching also was affected by temperature. These turtles' eggs took 49 days to hatch when incubated at 31 C. Those incubated at 26.5 C took about 2 weeks longer to hatch (Gutzke and Packard, 1987).

Hatchling Blanding’s turtles are born at a length of 29 to 39 mm, weighing 6 to 10 grams. Their shells are more rounded when they are younger, and gradually flatten as they age. In the first year of the Blanding’s turtles’ lives, they experience rapid growth in mass, as well as the length of their plastrons and carapaces. Their abdominal plates will, on average, increase about 70 percent in the first year. After the first year of rapid growth, they experience a decrease in growth rate over the next four years. This rate of growth ranges from 4 to 9 percent, and by their fourth year of life, the turtles reach complete adult size. These reptiles' ages can be determined by the number of annuli on their shells. Annuli are rings on the shells of turtles, where each ring marks a year of living.

When these turtles are 2 to 3 years old, the hinges of their plastrons can move. Once they are around 5 years, their plastrons can close completely and are fully hardened. At this point, their shell length is about 103 mm long. They can reach a maximum length of 240 mm and can weigh as much as 1400 grams.

Female Blanding's turtles have taller shells compared to the males, and the males tend to have wider shells than the females. Male turtles are more probable of having eroded and pitted shells compared to the females. This is hard to understand mainly because females in most turtle species have more erosion and pitting present, especially during breeding season when they use their shells to form healthy eggs. Males also can be distinguished from females by a light yellow coloring that covers the mouth of only the male turtles. (Congdon, et al., 2008; Graham and Doyle, 1979; Gutzke and Packard, 1987; Rowe, 1992a)

  • Development - Life Cycle
  • temperature sex determination

Reproduction

Blanding’s turtles are mostly polyandrous, meaning that females have more than one mate. It's rare for a female to only have a single mate. It is unknown whether the males usually mate with only one female turtle, or with multiple females. Because the clutches are products of more than one father, they are taken care of by multiple male turtles, usually only two, but on rare occasions there will be up to three mates. The number of males caring for one nest depends mainly upon the density of the population that the female Blanding's turtles inhabit. This process of multiple males caring for one nest is known as multiple paternity. Although the qualifications for a good mate remain mostly unknown, females give males a signal to mate with them by positioning their tail a certain way. The females have all of the control in the courtship process when it comes to choosing their mates. However, during courtship, the males are very aggressive and are the ones who seem to be in control, mounting the females and grabbing their carapaces. Courtship often starts under water where the male will proceed to mount on the female. The female will sometimes swim away from the male, and the male will chase, lasting less than 1 minute. As they begin to mate, the males will intensely bob their heads up and down, letting out air bubbles in big breaths under water. Males will also sway their heads side-to-side when mounting, often appearing violent. Head-to-head mounting is more normal, but there are instances where head-to-tail mounting occurs for only about 10 seconds. Blanding’s turtles will mate either on land close to an aquatic habitat or in water. The females tend to mate with the same males each year. Mating takes place at night. (Baker and Gillingham, 1983; Congdon, et al., 2008; Gibbons, 1968; Graham and Doyle, 1979; Refsnider, 2009)

Breeding takes place year round essentially for the Blanding’s turtles, but they mostly breed in the start of spring in March and early April. This is after their overwintering period. The female turtles reach sexual maturity at 14 to 21 years, averaging maturity at 18 years. Males tend to reach sexual maturity quicker at around 12 years. Females will only nest and lay eggs once a year, between the last weeks of June and the beginning of July. Sperm-storing is a reproductive feature of the females. These reptiles will usually nest nocturnally, and it takes them about 10 days to complete the nesting. In this 10-day period, they have to find safe spots with scarce vegetated soil. Lakeshores, cobble beaches and sides of roads are the common nesting spots. These particular areas present less predation. Searching for a nesting site can take the mothers 7 days or more, and they can travel over 7.5 kilometers in their search. Once they have found an appropriate site, the mother turtles begin constructing the nest , which can take upwards of 2.5 hours, and consists of the mother digging a 12 cm deep hole. The mother will then lay her eggs in the nest, after which she covers the nesting hole to bury the eggs,. Blanding’s turtles typically will nest in the same spot every year. Rarely, some turtles will end up choosing a variety of locations within a 2-kilometer range.

Clutch sizes range from 3 to 19, averaging around 10 eggs per clutch. Incubation temperatures are determinate in the sex of the turtles with incubation temperatures between 26.5 degrees Celsius and 30 degrees Celsius producing males and temperatures higher producing females. Older and larger females produce the largest clutches. There is no significant correlation between the egg size and the age or size of the turtles. The predation rates of the younger female turtles’ clutch sizes are a lot higher than that of older turtles, because older turtles tend to nest in safer areas.

The incubation period typically lasts between 80 and 128 days in the wild, and incubation temperature is a determining factor. In captivity, hatching took place after just 49 days when incubated at 31 C, and at about 63 days when incubated at 26.5 C. However, temperature in the wild likely are not this consistent, which leads to the larger range of hatching times. In the wild, hatchlings emerge during September and October. It takes the entire clutch 2 to 11 days to hatch. Hatchling turtles will weigh 6 to 10 grams at birth. Independent immediately after hatching, the hatchlings do not move or travel much in the first days of their lives. Eventually, they tend to move towards freshwater habitats, which are mostly sought after by the hatchlings in order to avoid freezing. However, they can be found overwintering in both terrestrial and aquatic habitats. Hatchling movement takes place in the middle of the morning and late afternoon. They are able to reach wetlands in 0.5 - 9 days, depending on their proximity to wetlands, usually being found in waters where populations are scarce and predation is minimal. (Congdon, et al., 2001; Congdon, et al., 2008; Dowling, et al., 2010; Gibbons, 1968; Gutzke and Packard, 1987; Kiviat, 1997; MacCulloch and Wayne, 1988; Refsnider, 2009; Rowe, 1992b; van Dijk and Rhodin, 2016)

  • Breeding interval
    Biannually
  • Breeding season
    After overwintering (March-April) ultimately, but occurs before overwintering at times (October-November). Incubation period occurs from June through August
  • Range number of offspring
    3 to 19
  • Average number of offspring
    10
  • Average number of offspring
    8
    AnAge
  • Range gestation period
    80 to 128 days
  • Range time to independence
    0 to 0 hours
  • Range age at sexual or reproductive maturity (female)
    14 to 21 years
  • Average age at sexual or reproductive maturity (female)
    18 years
  • Range age at sexual or reproductive maturity (male)
    12 (low) years
  • Average age at sexual or reproductive maturity (male)
    12 years

As female Blanding’s turtles contribute to the well-being of young by finding safe spots to bury the eggs, the males also contribute, usually in packs. Their parental investment occurs in multiple paternity, where multiple males look over the nest of one clutch to which they contributed genetically. There are usually male mates who have more eggs in the clutch that belong to them compared to the other contributors. However, this does not affect the amount of protection each male gives to the clutch, as each male contributes the same amount of time. Females leave the eggs once they bury the eggs in a safe nesting spot, and the males watch over the eggs from then on until the final days of the incubation period. (Congdon, et al., 2008; Refsnider, 2009; van Dijk and Rhodin, 2016)

  • Parental Investment
  • male parental care
  • pre-hatching/birth
    • provisioning
      • male
    • protecting
      • male
      • female

Lifespan/Longevity

The minimum expected lifespan of wild Blanding’s turtles is 70 years, while the maximum is 77 years. There are no known captive breeding programs, so information on the lifespan of captive Blanding’s turtles is not available. There has been confounding studies on whether male or female turtles live longer. However, studies have shown that there is an overall positive correlation between the age of Blanding’s turtles and survivorship. A 35-year survivorship study by Congdon (2001) showed that the older these turtles are, the higher their yearly survivorship rate, with no significant difference between the males and females. The annual survivorship of male and female adults (14+ years of age) is over 93%, while that of juveniles (1-13 years of age) is around 72% (Congdon et al., 1993). (Congdon, et al., 2001; Congdon, et al., 2008; Congdon, et al., 1993; McGuire, et al., 2013; Paterson, et al., 2014; Ruane, et al., 2008)

Behavior

Although Blanding’s turtles are mostly aquatic, they commonly emerge from the water to rest on logs, sedge clumps, or any terrestrial land that is close to their aquatic homes. These turtles will usually move when searching for habitats that are plentiful with food, mate accessible and also when the females are finding a good spot to nest. Beginning in mid-April and continuing through mid-July, there is hardly any traveling among these turtles. Turtles who inhabit the larger lakes will stay in their same locations for tens of years. Seasonal wetland inhabitants will change location and travel greater distances compared to the turtles occupying the lakes. Juvenile Blanding’s turtles also travel in their search for an aquatic habitat when they are first hatched, looking to find an adequate overwintering spot to lessen their chances of freezing to death. On land, males will travel more, found to on average travel over 10 km. Females however, only travel over 2 km, not including the nesting period of the females, where they can reach up to 7.5 km in travel. These turtles will travel between 1 to 230 meters daily in water. Older turtles usually live in the same spots together, ranging from 20 to 57 turtles per ha. During October and November, these reptiles will begin overwintering as a group, staying mostly in ponds, and they will hibernate until the end of March. Following their period of hibernation, they will begin breeding. Blanding’s turtles that are located in the more southern regions of their geographic range can withstand colder temperatures and will stay active in ambient temperatures as cold as 2 degrees Celsius

Ultimately, these turtles do not commonly display aggressive behavior, and hardly ever bite if handled by humans. Male Blanding’s turtles, however, are very aggressive toward the females during mating, forcefully mounting the females and bobbing their heads in an intense fashion. (Congdon, et al., 2001; Congdon, et al., 2008; Dinkelacker, et al., 2004; Gibbons, 1968; Graham and Doyle, 1979; Grgurovich and Sievert, 2005; Innes, et al., 2008; Kiviat, 1997)

Home Range

Blanding's turtles that inhabit small wetlands have a home range of 0.6 ha to 7.9 ha and 0.8 ha to 7.8 ha for females and males, respectively. The average home range for these turtles that live in more suburban ponds is 22 ha. When Blanding's turtles occupy larger open water areas like lakes, males have a much larger home range than females. The males average 56.9 ha and the females 18.9 ha. However, the older females have much larger home ranges than younger turtles and females also travel more. Blanding’s turtles do not actively defend their territory. (Congdon, et al., 2008)

Communication and Perception

During the mating season, male Blanding’s turtles rely on their tactile senses. Mounting is one of these tactile activities, as is gulping. In the latter activity, the males sway their bodies and spew water from their mouths onto the females’ head.

Hatchlings will use their vision most often in riparian habitats when moving to darker areas. In a study done by Butler and Graham (1995), they found that hatchlings will rely on their sense of smell when moving from the nest to a wetland. The juvenile turtles will utilize scent-trailing from other juvenile turtles in order to reach wetlands. Traveling for these hatchlings will take place in the morning and late afternoon. The adult Blanding’s turtles emit sounds under water while they swim. Although not certain why these turtles are vocalizing, possibilities could be for mating calls or defense. Giles (2005) thought vocalizations among 2 south american freshwater turtles were meant to communicate information with the community of the other turtles. ("Blanding's turtle: Emydoidea blandingii", 2015; Congdon, et al., 2008; Ferrara,, et al., 2013; Giles, 2005; Pappas, et al., 2009; Whitear, et al., 2016)

Food Habits

Blanding’s turtles are omnivores, but half of their diet consists of crustaceans, including crayfish. These reptiles will consume their food alive, or as carrion. They also eat insects and other invertebrates. These turtles resort to aquatic insects such as dragonfly nymphs and aquatic beetles when crayfish are not available in certain geographic locations, like Nova Scotia. Blanding’s turtles also will consume fish eggs, fish, frogs, and snails. They will eat coontail (Ceratophyllum demersum), duckweed (Lemna minor), sedge (Carex comosa), and bulrush (Scirpus) as well, and will also eat seeds. The adult turtles are more carnivorous, with up to over 75% of the diet being meat, while the juvenile Blanding’s turtles eat more plants. ("Blanding's turtle: Emydoidea blandingii", 2015; Congdon, et al., 2008; Ernst and Barbour, 1992; Harding, 2000; van Dijk and Rhodin, 2016)

  • Animal Foods
  • fish
  • eggs
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • aquatic crustaceans
  • Plant Foods
  • leaves
  • seeds, grains, and nuts

Predation

Northern short-tailed shrews (Blarina brevicauda) tend to prey on emerging hatchling Blanding’s turtles. Striped skunks (Mephitis mephitis), Virginia opossums (Didelphis virginiana), raccoons (Procyon lotor), and foxes also prey on the nests. When faced with predators, female turtles fend them off to protect their eggs and they could potentially die in doing so. These turtles are most safe during hibernation. The presence of ice in the turtles’ freshwater habitats can provide some protection from most predators, but North American river otters (Lontra canadensis) are still able to prey on them. When first hatching, they may stay in one spot in a protective stance, usually hidden in their shells, to avoid predators before venturing out to wetlands. (Congdon, et al., 2008; Edge, et al., 2009)

Ecosystem Roles

Nematodes (Spiroxys contortus) are common internal parasites of Blanding’s turtles, and there are multiple leech species that are ectoparasites of these turtles. In Canada, specifically Ontario and Nova Scotia, the smooth turtle leech (Placobdella parasitica), and the ornate turtle leech (Placobdella ornata) are found on Blanding’s turtles, which usually host these two parasites the most. These leeches are pathogens that can transmit a protozoan blood parasite (Trypanosoma chrysemydis). They are most commonly found on the necks, legs, shells, and tails of the Blanding’s turtles. The scutate snail leeches (Helobdella modesta) are common parasites of freshwater turtles, as well. Some of the less common leeches that are parasites to Blanding’s turtles, found in both Canada and the United States, are Erpobdella punctata and Alboglossiphonia heteroclita. These leeches can also transmit parasites from the genus Haemogregarina, a protozoan, to the red blood cells of Blanding’s turtles. ("Parasites of amphibians and reptiles from Michigan: A review of the literature 1916–2003", 2005; Congdon, et al., 2008; Davy, et al., 2009)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Blanding’s turtles are valued turtles in the pet trade, and are illegally collected by non-permitted trappers. These freshwater turtles are imported and exported specifically out of Texas as well as Japan. They are exported and imported for pet trade, where mostly female wild Blanding’s turtles are captured. They are the second most popular turtle species in commercial trade. ("Conservation status of live U.S. nonmarine turtles in domestic and international trade", 2002; Ceballos and Fitzgerald, 2004; van Dijk and Rhodin, 2016)

Economic Importance for Humans: Negative

There are no known negative effects that Blanding’s turtles have on humans.

Conservation Status

According to IUCN Red List, Blanding’s turtles are listed as endangered. These turtles are under Appendix II according to CITES, meaning they are not threatened with extinction, but it may come to this if trade is not controlled. and are under review for the U.S. Fish and Wildlife Service. The State of Michigan List has the Blanding’s turtles listed as Special Concern.

Blanding’s turtles are protected under Massachusetts, New York, Nebraska, Michigan, Minnesota state legislation and regulations. State and Federal administrations manage wetlands where these turtles are present and conservation action programs have emerged in these states. Blanding’s turtles are listed as endangered in Nova Scotia and threatened in the Great Lakes and St. Lawrence region by Canada’s Species at Risk Act.

The female turtles often create roadside nests. As a result, road mortality is high for Blanding’s turtles. Furthermore, these freshwater turtles run into nest predators at times when constructing their nests or burying the eggs. Males, when protecting the nests, will also face the nest predators. Conservation measures have included attempts to reduce road mortality with the implementation of fences and road passages, and turtle crossing signs, now present in Nebraska and Minnesota. Another recommended conservation strategy is to eliminate nest predators via trapping. There are removal efforts in Minnesota that prohibit herbicide usage in known wetland habitats of the Blanding’s turtles. With this, wetland buffer zones is another highly recommended conservation effort, meaning road construction and building developments are only allowed within certain distances from the wetlands. ("Blanding's Turtle (Emydoidea blandingii) in the Brainerd/Baxter Region: Population status, distribution and management recommendations", 1998; Congdon, et al., 2008; ; van Dijk and Rhodin, 2016)

Contributors

Evan Grey (author), Radford University, Alex Atwood (editor), Radford University, Marisa Dameron (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males