Blanding’s Turtle

Scientific Name	Emydoidea blandingii
Survival Strategy	Brumation
Conservation status	Endangered

Phenology

Spring
Blanding’s turtles come out of brumation and become active as the water temperature increases, typically from March to April. On sunny days they will bask on logs or piles of vegetation near enough to the water to submerge quickly at the first sign of danger. Most breeding occurs from May to June, although researchers have documented mating in September and October. After mating, the female will travel up to a kilometer to find a suitable nesting site that features well-drained, sandy soils.

Summer
The female Blanding’s turtle will lay a clutch of 10 to 26 eggs from late May to early July. The eggs incubate for 75 to 110 days. The precocial hatchlings emerge from their nest and navigate to freshwater using the sun as a compass. As summer progresses, adult Blanding’s turtles will move between wetlands in response to seasonal changes in water quality and food availability.

Fall
If the wetlands they used during the active season are unsuitable for winter, Blanding’s turtles will migrate to more “winter friendly” sites in September and October.

Winter
Blanding’s turtles typically overwinter in a state of brumation. They remain buried in the muddy bottoms in the deepest parts of marshes, ponds, and streams for most of November through March. Biologists have documented Blanding’s turtles swimming slowly under the ice and even basking on the ice margins of their overwintering ponds.

Behavior

Estivation
Blanding’s turtles are less tolerant of warm temperatures than other aquatic turtles. They will often estivate during extended periods of hot and dry weather that are common in July and August in the upper Midwest. They leave their wetlands and temporarily relocate to wooded uplands, where they bury themselves in leaves or burrow underground to avoid the heat and conserve moisture. By decreasing their breathing, heart rate, and metabolism, they can save energy until conditions improve.

Physiology

Brumation
Blanding’s turtles are more tolerant of colder temperatures than snapping turtles or painted turtles and can stay active in early winter. They enter brumation when the water temperature falls to about 10°C (50°F), at which time their heart rate can drop to one beat every 10 minutes. When basking in the summer sun, their heart rate is around 40 beats per minute.

Turtle Shell 101
Turtle shells are made of fused bones covered by skin that holds blood vessels and sensory nerves. The outer surface is divided into sections called scutes made of keratin (the same material that makes up our fingernails).

Turtle shells have three main parts. The upper shell, called the carapace, is formed from the rib cage and the spinal column with the spinal cord running through it. The lower shell, called the plastron, is formed from the shoulder girdle and sternum. The carapace and plastron are fused along the sides of the shell, forming the bridge.

Box turtles have a hinge on their plastron that allows them to protect their head and tail if threatened by a predator. Blanding’s turtles are called semi-box turtles because only the front portion of the plastron is hinged. The plastrons of snapping turtles and painted turtles are not hinged. In most turtles, the plastron of males that have reached sexual maturity is concave to make mating easier.

Butt Breathing
Lungs are of no use under the winter ice. Like other aquatic turtles that brumate underwater, Blanding’s turtles absorb oxygen through capillaries in their mouth and cloaca; in other words, they breathe through their butts.

Gender Determined by Incubation Temperature
The temperature of the nest determines the gender of Blanding’s turtles. Eggs incubated in temperatures below 25ºC (77ºF) will produce almost all males, while nest temperatures above 30ºC (86ºF) will result in primarily female hatchlings.

Diet

Blanding’s turtles are omnivores. Their diet includes invertebrates, fish and fish eggs, carrion, frogs, toads, and tadpoles. They will also eat leaves, seeds, and fruit.
Unlike snapping turtles and painted turtles, Blanding’s turtles can swallow food without being in the water

Lifespan and Mortality

Blanding’s turtles can live for more than 70 years.

Predators
Blanding’s turtle eggs, hatchlings, and juveniles are preyed on by raccoons, foxes, skunks, wading birds, and fish. Predators destroy over 90% of the nests. Predation of adult Blanding’s turtles is uncommon due to its ability to protect its head by closing the front of its shell. Otters can hunt Blanding’s turtles under the ice and are responsible for the loss of occasional brumating adult turtles.

Roadkill
Blanding’s turtles travel up to one kilometer (0.62 mi) to lay their eggs, and in turn, the hatchlings will travel a similar distance to reach the relative safety of the water. By spending more time out of the water than most turtles, they are at greater risk of accidentally or intentionally being hit by cars, trucks, or UTVs.

Illegal Pet Trade
The collection of Blanding’s turtles for the illegal pet trade is a serious threat to the survival of this species. These turtles are slow breeders that take up to 20 years to reach sexual maturity. The loss of adults can drastically reduce local populations. Blanding’s turtles are protected in nine of the13 states where they are found but currently have no federal protection.

Climate Vulnerability

The effects of a warming climate on the Blanding’s turtle lacks data and needs further study. The increase in weather extremes may create drought conditions in parts of the turtle’s range. Researchers suspect that a drier climate may require longer migrations between suitable wetland habitats while at the same time providing more nesting sites. With 20 years before breeding age, the recovery of local populations will take a long time, making the Blanding’s turtle particularly vulnerable to climate change.

Never stop learning

Naming Rights: The Blanding’s turtle is named for American naturalist Dr. William Blanding, who is credited with discovering the turtle that now carries his name. With fossil records dating back at least 9000 years, it is safe to assume that the Blanding’s turtle was “discovered” long before Dr. William Blanding was born.

References

Sajwaj, Todd & Lang, Jeffrey. (2000). Thermal Ecology of Blanding’s Turtle in Central Minnesota. Chelonian Conservation and Biology. 3. https://www.researchgate.net/profile/Jeffrey-Lang/publication/255965456_Thermal_Ecology_of_Blanding’ s_Turtle_in_Central_Minnesota/links/00b7d52116ffd309be000000/Thermal-Ecology-of-Blandings-Turtle-in-Central-Minnesota.pdf

Emydoidea blandingii : Blanding’s Turtle | Rare Species Guide | Minnesota DNR https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=ARAAD04010

Grey, E. 2016. “Emydoidea blandingii” (On-line), Animal Diversity Web. Accessed February 26, 2022 at https://animaldiversity.org/accounts/Emydoidea_blandingii/

van Dijk, P.P. & Rhodin, A.G.J. 2011. Emydoidea blandingii (errata version published in 2019). The IUCN Red List of Threatened Species 2011: e.T7709A155088836. https://dx.doi.org/10.2305/IUCN.UK.2011-1.RLTS.T7709A155088836.en

Wisconsin Department of Natural Resources. 2014. Wisconsin Blanding’s Turtle Species Guidance. Bureau of Natural Heritage Conservation, Wisconsin Department of Natural Resources, Madison, Wisconsin. PUB-ER-683. https://dnr.wi.gov/files/PDF/pubs/er/ER0683.pdf

Lee, Y. 1999. Special animal abstract for Emydoidea blandingii (Blanding’s turtle). Michigan Natural Features Inventory. Lansing, MI. 4 pp. https://mnfi.anr.msu.edu/abstracts/zoology/Emydoidea_blandingii.pdf

COSEWIC. 2016. COSEWIC assessment and status report on the Blanding’s Turtle Emydoidea blandingii, Nova Scotia population and Great Lakes/St. Lawrence population, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xix + 110 pp. https://publications.gc.ca/collections/collection_2017/eccc/CW69-14-222-2017-eng.pdf

Northeast Blanding’s Turtle Working Group http://www.blandingsturtle.org/

Status Assessment for the Blanding’s Turtle (Emydoidea blandingii) in the Northeast http://www.blandingsturtle.org/status-assessment-2007.html

Gasbarrini, D.M.L. & Lesbarrères, David & Sheppard, A. & Litzgus, Jacqueline. (2021). An enigmatic mass mortality event of Blanding’s Turtles ( Emydoidea blandingii ) in a protected area. Canadian Journal of Zoology. 99. 10.1139/cjz-2020-0204. https://cdnsciencepub.com/doi/10.1139/cjz-2020-0204

Encyclopedia of Life: Blanding’s Turtle https://eol.org/pages/1056352

Sethuraman, & Mcgaugh, Suzanne & Becker, Morgan & Chandler, Christopher & Christiansen, James & Hayden, Sue & LeClere, Andrea & Monson-Miller, Jennifer & Myers, Erin & Paitz, Ryan & Refsnider, Jeanine & Vandewalle, Terry & Janzen, Fredric. (2013). Population genetics of Blanding’s turtle (Emys blandingii) in the midwestern United States. Conservation Genetics. 15. 61-73. 10.1007/s10592-013-0521-8. https://www.researchgate.net/publication/260338671_Population_genetics_of_Blanding%27s_turtle_Emys_blandingii_in_the_midwestern_United_States

Krenz, J.D., Congdon, J.D., Schlenner, M.A. et al. Use of sun compass orientation during natal dispersal in Blanding’s turtles: in situ field experiments with clock-shifting and disruption of magnetoreception. Behav Ecol Sociobiol 72, 177 (2018). https://doi.org/10.1007/s00265-018-2590-7

Evrard, J. O. and M. E. Canfield. 2000. Blanding’s turtles in the Crex Meadows Wildlife Area. Transactions of the Wisconsin Academy of Scienced, Arts and Letters 88:49-54. https://images.library.wisc.edu/WI/EFacs/transactions/WT2000/reference/wi.wt2000.joevrard3.pdf

Helping Blanding’s Turtles Get Ahead with a Head Start https://www.sheddaquarium.org/stories/helping-blandings-turtles-get-ahead-with-a-head-start

What’s Inside A Turtle Shell? https://youtu.be/V17T_5jRE2M