Blanding's Turtle (Emydoidea blandingii)

Legal Status in U.S.: Unprotected Legal Status in Wisconsin: Threatened Length: 8 to 10 inches Weight: Up to 3 pounds Range in Wisconsin: Throughout the state except the extreme north-central counties.

Description || Distribution and Habitats || Life History || Current Status || Excerpt from the Animal Guide

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Turtles are an important link to the past history of life on earth. It is believed that turtles have survived for millions of years as inhabitants of our planet; however today, here in Wisconsin, many turtle species are being threatened. One such species is the timid, gentle Blanding's turtle.

Named after its discoverer, the Blanding's turtle is medium-sized. It can be easily identified by the bright yellow underside of its neck. Its head, tail, and limbs are blue-black, while the underside of its shell (or plastron) is yellow, with brown or black splotches, and is hinged. Its upper shell (or carapace) is usually black speckled with yellow, or horn colored and mottled with brown. The young are patterned differently from adults; their shells help them blend in with their surrounding environment. The hinge of the Blanding's turtle's plastron is not functional until the turtle is 3 to 5 years old. Before this age its yellow throat markings are not apparent. The function of the yellow chin is unknown (perhaps it has something to do with mating). Males are larger than females, have longer tails, and their plastrons are concave for mating. The hinged plastron allows the turtle to close the front half of the shell tightly, protecting the soft flesh of its head, neck, and legs from predators. Due to this behavior, this species is sometimes referred to as the "semi-box turtle."

Distribution and Habitat

The original range of the Blanding's turtle extended from southern Ontario and northwestern Pennsylvania in the East, through Ohio, Indiana, Michigan, Illinois, Wisconsin, and southern Minnesota and is found in Nebraska, Iowa, and extreme northeastern Missouri in the West.

In Wisconsin, Blanding's turtles live throughout the state with the exception of the extreme north-central counties. They are most concentrated in the vast marshes along the Wisconsin River in Wood, Juneau, Adams, and Iowa counties. While Blanding's turtles live primarily in marshes and the shallow bays of lakes, they also can be found in shallow, slow-moving rivers, streams, and some northern bogs.

Life History

The Blanding's turtle is semi-aquatic. It prefers open, grassy marshes containing shallow water, but it will, on occasion, move to ground adjacent to water to forage or bask in the sun. While in the water, it feeds on crustaceans, snails, insects, frogs, and fishes. Crayfish appear to be a preferred food when available. When on land, however, it consumes earthworms, slugs, grasses, berries, and succulent vegetation. The Blanding's turtle is unique because, unlike most turtles, it can swallow food both in and out of the water. During the winter, it hibernates by burying itself in the silt on the bottom of the pond, bay, or river it inhabits which reduces its chances of freezing.

Blanding's turtles require 15 to 20 years to mature. Mating usually occurs in the water during early spring. After fertilization, females will bask in the sun with their heads and legs fully extended. This warming behavior, called thermoregulation, speeds the development of their eggs enabling them to be laid sooner. This gives the eggs a better chance of hatching before the autumn frost. This, in turn, allows the hatchlings to grow before hibernating, giving the immature turtles a greater chance of surviving the winter. About one-half of the female population breeds annually. Like all turtles, they must lay their eggs on land and prefer a patch of sandy ground for nesting. They will travel up to one and a half miles from water to nest, and they usually return to the same nesting site each year. They typically lay their eggs during the late afternoon or after dusk. Once they deposit the eggs in the ground, the mothers return to the water, and the sun's warmth is used to incubate the nested eggs. The clutch may contain from 3 to 17 elliptical eggs. Between 65 and 90 days pass before they hatch.

The nests, however, are not safe. Subject to predation by birds and small mammals such as crows, skunks and raccoons, many eggs are lost in the first 24 hours of incubation. Those that do hatch are in danger of additional predation and highway mortality as they travel to their aquatic habitat. Hatchlings are about one and a quarter inches long and range from dark gray to greenish in color. Little is known about the habits of the young. They appear to be very secretive, foraging exclusively in aquatic habitats which are densely vegetated. Once they are about 6 inches long they can be seen basking and foraging more easily and often.

Even fully grown the Blanding's turtle is one of nature's most timid creatures. Due to their shyness, they must be approached very delicately if they are to be observed. If disturbed on land, the Blanding's turtle will pull itself tightly into its shell. If it is basking in an aquatic environment, it may quickly dive and remain hidden in the watery depths if it senses danger. It will remain at the bottom for 20 to 30 minutes at a stretch before again peeking carefully above water. Though shy, the Blanding's turtle is also exceedingly gentle and will very rarely attempt to bite.

Current Status

Maintaining both its aquatic and terrestrial environments is critical to the survival of the Blanding's turtle. Its population in parts of Wisconsin has become limited as natural wetlands are drained in preparation for suburban development or for conversion to soil adequate for farming. These practices dramatically affect the local turtle population by shrinking and fragmenting its habitat. In addition, the introduction of new roads with increased traffic results in the accidental killing of Blanding's turtles as their shells cannot withstand the weight of an automobile. A road presents a major hazard if its placement requires the turtles to cross it to either lay their eggs or to reach their non-aquatic foraging grounds. Wet-lands - with adjacent territory - provide the stable environment needed for the well-being of the Blanding's turtle. Without this stable environment, the future of this and many other species is threatened.

Excerpt from THE ENDANGERED AND THREATENED VERTEBRATE SPECIES OF WISCONSIN

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Status: State Threatened (1979).

Occurrence: Found throughout most of Wisconsin except for the mature hardwood forests region of the northern counties.

Aid to ID: Medium sized semiaquatic turtle characterized by a long neck and a bright yellow throat, a distinct plastron (bottom shell) hinge, and a smooth carapace (top shell). Head, tail and limbs are blue-black or brown, the plastron is blue-black or brown and yellow, and the carapace is usually black speckled with yellow. Males are larger than females, have longer tails, and have concave plastrons. Hatchlings are dark gray or greenish and have a tail that nearly equals the carapace length.

Habitat: Prefer shallow and deep marshes, the shallow bays of lakes and reservoirs, shallow, slow moving streams and rivers, and backwater sloughs with soft bottoms and aquatic vegetation. Rarely found in northern forested regions, fast moving rivers or northern bogs.

Food Habits: Forage in water and on land. Omnivorous diet includes: crustaceans, snails, insects, frogs, crayfish, earthworms, slugs, grasses and berries.

Natural History:

Active: Diurnally April to November. Will frequently leave water to forage in open, wetland fringe communities.
Hibernation: November to April in mud or debris on bottom in deeper water ponds and streams.
Reproduction: Mate in early spring and fall, usually in water. Females lay clutches of 6-15 (avg. 10) eggs beginning in June during late afternoon or at dusk. Use sandy, open, upland sites up to 1.5 miles from water. Eggs hatch in 65-90 days. Sexually mature in 14-20 years. Females breed every other year.

Management Considerations: Threatened by habitat loss and fragmentation due to draining of wetlands, heavy nest predation, highway mortality, and low nesting frequency. Predator exclosures may effectively reduce predation where nesting is concentrated. Barriers along roadways have proven effective in reducing adult turtle mortality.

Information compiled from publications ER-529 92REV and ER-091.

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