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Blanding’s Turtle

Overview:

Scientific Name: Emydoidea blandingii

Size: 6 – 10.8” (adult carapace length)

Status: Vulnerable and generally declining at periphery of their range. Destruction and degradation of wetlands and adjacent uplands has led to local extirpation in many areas though this species can be relatively common where suitable habitat exists. 

Michigan State Status: Special Concern

Federal Status: Candidate Under Review

MDNR Wildlife Action Plan Status: Species of Greatest Conservation Need

Habitat:

Inhabit shallow, weedy waters such as ponds, marshes, fens, swamps, and lake inlets and coves. Sometimes found in rivers but mainly active in backwaters, embayments, and sloughs. Terrestrial movement is common in the spring mating period. 

Conservation:

The Blanding’s turtle inhabits a range that encompasses the Upper Midwest, and Southern Canada, as well as in scattered, isolated populations in New England and Novia Scotia. Currently, Blanding’s turtles are a species of special concern in Michigan and are under further federal review to determine if this species’ conservation status should be elevated to endangered. Across their distribution, Blanding’s turtles face threats such as habitat loss/fragmentation, nest predation, and road mortality which put this species at increased risk of extirpation. Furthermore, unique life history traits such as prolonged terrestrial travel during breeding season and delayed sexual maturity make the Blanding’s turtle particularly vulnerable to these threats. The demand for Blanding’s turtles in the illegal pet trade has also contributed to their extirpation, as the aesthetically pleasing colors on their shells have significantly increased their popularity on the market. Currently, Blanding’s turtles are so immensely popular in the illegal wildlife trade that they are considered the second most trafficked turtle on the market (Ceballos and Fitzgerald, 2004).  

Best Management:

Identify and protect suitable habitat containing extant populations of Blanding’s turtles. Suitable habitat consists of a mosaic of various wetland and adjacent upland habitat. Maintain habitat connectivity between wetland and upland habitat. Minimize habitat fragmentation and establish buffer zones around development in close proximity to Blanding’s turtle habitat. Ensure mature adults and older juveniles remain on the landscape to maintain population stability. Captive rearing head-start programs can be an effective tool in stabilizing populations in decline. Introduce predator controls to eliminate over-predation and increase the success of nests. Maintain adequate water quality by using vegetated buffer zones between areas of chemical application and aquatic system. Identify and prevent non-point nutrient and chemical runoff from entering the system. Prevent the introduction of invasive species. Avoid mechanically harvesting aquatic vegetation. Consider creating or restoring vernal pools. Do not impact the pool depression or core buffer area within a minimum of 100 feet and aim to protect a wider buffer of 600-1000 feet. Maintain a forest canopy of at least >50% and use coarse woody material to create simple habitat structures. Avoid altering water levels and consider adding hibernacula structures by creating hollowed-out areas under the banks, ensuring they are submerged or at a constant water level from early fall to early spring. Implement turtle basking structures by felling trees or utilizing existing logs and partially submerging them in a sunny location to provide basking habitat. Minimize road mortality by preventing habitat fragmentation and installing wildlife barrier fencing or crossing structures to redirect Blanding’s turtle movement during peak active season. Monitor sites consistently to prevent the collection of spotted turtles for the illegal wildlife trade and report suspicious activities to wildlife law enforcement. 

Adult Coloration:

The carapace is black or grown often marked with a variable pattern of tan or yellowish spots or streaks. The plastron is yellowish with a dark blotch at the outer rear edge of each scute. Although rare, a dark coloration may cover most or all of the plastron. The top and sides of the head are black, brown, or olive with yellowish or brownish spots or mottling while the chin, throat, and lower neck are bright yellow.  

Adult Characteristics:

A moderately high, domed carapace that is elongate and smooth without keels or sculpturing. The plastron usually has well-defined annuli and a shadow V-shaped notch at the tail. Most adults have a hinge between the pectoral and abdominal scutes with varying flexibility. The head is flat with a short, rounded snout. The neck is relatively long. The upper jaw is notched at the front giving the species a permanent “smile.” Males have a moderately concave plastron and a wide tail with the vent beyond the edge of the carapace. Females have a flatter plastron with a narrow tail with the vent at or beneath the edge of the carapace.  

Mass: 750 to 1400g 

Typical Lifespan in Wild: 70-77 years 

Breeding Interval: Biannually  

Breeding Season: April-October (Incubation: June-August) 

Range of number of offspring: 3-19  

Average number of offspring: 8-10 

Range gestation period: 80-128 days 

Average age at sexual/reproductive maturity (female) 18 years 

Average age at sexual/reproductive maturity (male): 12 years 

Diet: The Blanding’s Turtle is primarily a carnivore that feeds on terrestrial invertebrates, fish, eggs, insects, non-insect arthropods, carrion, aquatic crustaceans, as well as leaves, seeds, grains, and nuts 

Known Predators: Northern Short-tailed Shrews, Striped Skunk, Virginia Opossum, racoon, North American River Otter 

Juvenile Characteristics:

The carapace can be grey, brown, or black, that is 1.2 – 1.4” long with a low keel and sometimes a light spot in the center of each scute. The plastron has a black central blotch that is rimmed by yellow or cream color. The tail is proportionally longer and thinner than an adult. Often, they are more brightly marked overall than adults and the carapace scutes may show distinct growth rings.

Species Confused With:

Wood Turtles have a lower, broader, more sculptured carapace and an unhinged plastron. Spotted Turtles are much smaller and have larger, more rounded spots on the head and carapace while lacking a plastral hinge. The Eastern Box Turtle has a hooked (not notched) upper jaw and generally does not have a solid yellow throat and neck.  

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