Species Description
With a speckled shell and bright yellow neck and jaw, Blanding’s Turtles are quite striking in appearance. Their highly-domed shells get up to 10 inches long, are dark in color, and often covered in small yellow spots or stripes. The plastron (bottom of their shell) is yellow with dark blotches in the corner of each scute (armored plate), but can sometimes be solid black or stained red from minerals in the water. The plastron also has a flexible hinge, allowing for partial closure of the shell. Their legs and top of their head and neck are darkly colored, sometimes with yellow spots, similar to the color and pattern of the carapace (top of the shell).
Taxonomy
Blanding’s Turtles are a member of the Emydidae family, which they share with most other freshwater turtles in North America, apart from Snapping Turtles, Softshells, and Tortoises. The sole member of the genus Emydoidea, Blanding’s Turtles are most closely related to other turtles in the in the Emydinae subfamily (sometimes referred to as the Clemmys complex), including Spotted, Wood, and Bog Turtles. In the early 2000s, when the Clemmys complex was reorganized based on genetic data, Blanding’s Turtles were almost grouped with Western Pond Turtles (presently Actinemys mormorata) and European Pond Turtles (Emys sp.), all of which are separated by vast geographic distances, but the Blanding’s and Western Pond Turtle are currently recognized by the Committee on Standard English and Scientific Names as each belonging to their own monotypic genus. Internationally, NatureServe groups Blanding’s Turtles in the Emys genus with European Pond Turtles, and their classification remains a topic of debate.
Distribution
The Blanding’s Turtle range centers around the Great Lakes region, extending west into Central Nebraska, and north into Southern Ontario and Quebec, with additional populations in the Hudson River Drainage of New York, coastal regions of Massachusetts, New Hampshire, and Southern Maine, as well as central Nova Scotia. While most of the species’ western range is contiguous, populations in the East are disjunct and often separated by vast distances, with most occurring within a ~75-mile radius around the city of Boston or in the Saint Lawrence and Hudson River drainages.
Habitat
Blanding’s Turtles are a wetland specialist, but the types of wetlands they inhabit vary considerably, and Blanding’s Turtles often travel great distances across land between wetlands. Areas with many wetlands in close proximity, separated by unfragmented forest, are ideal habitat where Blanding’s Turtles may thrive. Suitable wetlands typically have slow-moving or standing water less than 6.5 ft. deep with abundant aquatic and emergent vegetation. Scrub-shrub swamps, marshes, vernal pools, bogs, ponds, lake margins, flooded prairies, forested wetlands, and river floodplains can all be used by Blanding’s Turtles, and turtles sometimes use several kinds of wetlands in a single year.
Blanding’s Turtles may travel more than a mile over land, but most of their terrestrial movements occur within ~650 ft. of wetlands. Forests surrounding Blanding’s Turtle wetlands are usually dominated by hardwoods and have sandy soils (sometimes well-drained loam or fine gravel), as well as small clearings with exposed soil where the females will nest. In some areas, Blanding’s Turtles will also utilize agricultural habitat, especially while nesting when females can be drawn to recently tilled fields.
Natural nesting habitat for Blanding’s Turtles is rare and consists mostly of rock outcrops and recently-disturbed sandy habitat. Historically, females likely traveled great distances over land to find open habitat with exposed soils to for nesting, but turtle movements are now limited by roads, developments, and other hazards. In some cases, females travel over a mile across both land and water to nest and may cross several roads in the process, but the vast majority of nesting occurs very close to wetlands. Today, most Blanding’s Turtles nest in anthropogenic settings where turtles and their nests are at elevated risk of being killed by cars, machinery, or predators. Examples of anthropogenic nesting habitat include road shoulders, log landings, farm fields, lawns and gardens, construction sites, sand pits, and artificially constructed nest sites installed for conservation purposes.
Movement and Home Range
Blanding’s Turtles emerge from their winter dormancy as early as Mar. 15 and begin basking on logs, floating mats of vegetation, or on land (often concealed by leaflitter), but will not venture far from wetlands until the risk of severe frost has passed. They soon begin traveling over land from one wetland to another, and are especially drawn to vernal pools where amphibian eggs provide a seasonally abundant food supply. While Blanding’s Turtles may cross roads at any time during their active season (Mar. 15 – Nov. 15), females cross roads much more frequently during the nesting season (May 15 – Jul. 10) while searching for a suitable nest site, sometimes traveling over a mile across both land and water before returning to their wetland foraging habitat.
Apart from nest searching, most terrestrial movements occur in forested habitat between wetlands, with turtles typically spending no more than a week on land at a time. In some cases, Blanding’s Turtles may aestivate on land for longer periods during severe droughts. As the risk of frost returns in the fall, the turtles cease their terrestrial wanderings, returning to their core wetland habitat by Nov. 15, and will seldom venture out of the water again until spring. While Blanding’s Turtles utilize many wetland types in the summer, suitable overwintering wetlands have stable water levels and tend to be deeper than many of the wetlands where they forage. Through the winter, the turtles may occasionally shift locations, but typically move less than 20 ft. until mid-March when they emerge once more.
Diet
The diets of Blanding’s Turtles are highly varied, but consist largely of crayfish, snails, slugs, larval dragonflies, other aquatic insects, and small fish. Frogs and salamanders, including lavae and adults are also regular prey items for the species. Crayfish in particular appear to be a mainstay on a Blanding’s Turtle’s menu, with some studies finding over half of the stomach contents of adult Blanding’s Turtles consisting of crayfish. As omnivores, Blanding’s Turtles also consume a variety of plant matter, including pondweed, berries, and leafy vegetation.
Blanding’s Turtles primarily feed in the water where they use their wide gape, long neck, and expanding throat to create a vacuum and suck prey into their mouths. Blanding’s Turtles occasionally feed on land, but observations of terrestrial feeding in the wild are limited.
Reproduction
Females are slow to reach sexual maturity, and may not lay eggs until around 20 years of age, after which point they lay between 4 and 17 eggs most years, in a single clutch. The nesting season starts around May 15 and extends through July 10, and most nesting takes place in the evening between 6 and 10 pm. Like most other turtles, sex determination is based on nest incubation temperature. Eggs incubated at 72-80°F will produce mostly males, while all eggs incubated at 86°F or greater will hatch into females.
Eggs hatch by Oct. 15 (usually in August or September), but nest survival rates can be very low, even in undisturbed settings. Hatchlings and juveniles are more vulnerable to predators, which include chipmunks, crows, and larger mammalian carnivores such as otters and raccoons that can also injure or kill adults. Those that survive to adulthood may live a very long time, with several confirmed cases of wild Blanding’s Turtles surviving into their mid-70s and 80s, at which point females are still capable of laying eggs. The longevity and high survival rates of adult female Blanding’s Turtles is an important factor in the survival of their populations.
Conservation Concerns
With many wetlands historically drained for farming and development, and remaining habitat closely bounded by roads, residential areas, and commercial developments, many of the remaining Blanding’s Turtle populations are separated by vast distances or physical barriers such as roads. Habitat loss continues today, with forested land near wetlands being developed for residential and commercial use, which results in more roads and increased traffic. When turtles cross roads, trails, fields, and developments, they can be crushed by cars and heavy equipment, or unlawfully collected when people encounter them, either to be kept as pets locally or sold through an international black market. Even within relatively in-tact habitat, Blanding’s Turtles can be crushed by logging equipment and ATVs.
The most urgent threats include, mortality caused by cars, ATVs, and farming or forestry equipment, increased predation of nests and young, insufficient or degraded nesting habitat, invasive plant species, especially at nest sites, continued habitat loss and fragmentation caused by new developments and roads, and incidental collection combined with black market poaching.
Where Blanding’s Turtle sites lack sufficient nesting habitat, females travel farther to lay eggs, or wander into high risk areas such as residential developments, across roads, and into agricultural fields. After nesting, predation rates of their eggs can be exceptionally high, especially near residential areas and working farms where the populations of raccoons, skunks, and other mammalian predators are higher. In extreme cases, predators may even stalk nesting turtles and consume their eggs moments after a female lays. After hatching, young Blanding’s Turtles are heavily preyed upon by the same predators that destroy nests, as well as smaller predators like chipmunks and birds. Many hatchlings are consumed before ever making it to water.
Exacerbating the issue of low nest and hatchling survival, open sandy areas ideal for nesting are also popular destinations for off-road vehicle recreation, which endangers nest-searching females, eggs, and hatchlings, all of which can easily be crushed by ATVs. Nesting habitat is often further degraded by invasive plant species, such as spotted knapweed and mugwort, which can overrun the habitat and shade out nests.
Because Blanding’s Turtles take upwards of 20 years to mature, can live into their 80s, and have very low reproductive and juvenile survival rates, the longevity and survival of adults is absolutely critical to the conservation of the species, as is their ability to nest successfully. If Blanding’s Turtles are to persist, their core wetland habitat and connecting tracts of unfragmented forest need to be conserved or restored, nest sites need to be created or enhanced near their wetlands and away from roads, and steps need to be taken to reduce adult death rates, especially in high risk settings such as roads, ATV trails, and farm fields.