Each year in early to mid-June, over 1,000 gravid (with eggs) female Blanding’s turtles move from marshes and wetlands associated with the old Zumbro River channel and cross Wabasha County Road 84 and make their way to traditional nesting areas at Weaver Dunes Preserve Scientific and Natural Area.
Although listed as a threatened species in Minnesota, Blanding’s turtles still occur in substantial numbers in the vicinity of Weaver Dunes in the southeastern region of the state. In fact, this population may represent the largest concentration of Blanding’s turtles existing anywhere in the United States, with an estimated 5,000+ individuals believed to currently inhabit the region’s wetlands.
The Nature Conservancy’s involvement in protecting the Blanding’s turtle habitat in the Weaver Dunes area goes back to 1980, when The Nature Conservancy acquired the Weaver Dunes Preserve. The American Museum of Natural History calls this dune region the most important place in the United States for these turtles because of the population’s wide range in age and size.
Blanding’s turtles are a medium-sized species with domed shells averaging 7 to 9 inches long. They were named for William Blanding, an early Philadelphian naturalist who discovered them. A distinguishing feature is the bright yellow chin and throat. Its shell, which resembles an army helmet, is usually dark olive in color with irregular pale yellow spots. The range of the turtle is concentrated in the Great Lakes region, including Michigan, Wisconsin, northern Ohio, Indiana and Illinois, southern Minnesota, Iowa and Nebraska. It is also found in southern Ontario and as far east as northern New York. It is listed as state endangered in Indiana and Missouri and state threatened in Illinois, Iowa, Minnesota and Wisconsin.
Blanding's turtles are not aggressive and rarely bite. Instead, they pull their head and limbs inside their shell and close the front hinge to protect themselves.
The primary threat to the Blanding's turtle is habitat fragmentation and loss, such as the draining and filling of wetlands. They have few natural predators as adults, although animals such as raccoons, foxes and skunks often take their eggs. Adults are also vulnerable to automobiles during migration.
The preferred habitats for Blanding's turtles are shallow wetlands and marshes. Each year in early to mid-June, female Blanding’s turtles migrate to lay their eggs in open, sandy areas, walking up to a mile to find the “perfect” nesting site. Once a nest site is chosen, the turtle digs a hole 4 to 6 inches deep and deposits an average of 10 eggs. The eggs hatch in late August, and the hatchlings return to the wetlands using the same routes as the adults. These migrations are hazardous for the turtles because they must cross roads and highways on their journey.July 26, 2012