Rare Species Guide

  Synonyms

Emys blandingii

  Basis for Listing

Although formerly more widespread in the eastern and central portion of the United States, the Blanding's turtle is now restricted to a small number of states and provinces in the Upper Midwest, New England, and southeastern Canada. Minnesota lies on the northwestern periphery of its range and the species is relatively widespread in the state. Although most populations within the state are restricted in size, there is an area of sand dunes and extensive marshes and backwaters along the Mississippi River which provides habitat for one of the largest populations of this species (Hamernick 2000; Pappas et al. 2000). The Blanding's turtle is a late maturing, long-lived species unable to recover quickly from catastrophic events that reduce the population (Congdon et al. 1993). Their relatively low mobility, high juvenile mortality rate, and low reproductive potential are also limiting factors for population growth. Loss and degradation of upland and wetland habitats, and mortality on roads are great threats to the species (Sajwaj et al. 1998). The Blanding's turtle was classified as a threatened species in Minnesota in 1984.

  Description

The Blanding's turtle averages 15-25 cm (5.9-9.8 in.) in length. Its most diagnostic characteristics are its domed upper shell (carapace) and its bright yellow chin and throat. The dark carapace typically has numerous, scattered yellow flecks. Adult males have a slightly concave lower shell (plastron) and a longer and thicker tail than females, with the vent extending beyond the rear edge of the carapace. Blanding's turtles are often referred to as semi-box turtles because their plastron is hinged across the front third. This hinge enables the turtle to pull the front edge of the plastron firmly against the carapace to provide additional protection when threatened.

  Habitat

Wetland complexes and adjacent sandy uplands are necessary to support viable populations of Blanding's turtles. Calm, shallow waters, including wetlands associated with rivers and streams with rich aquatic vegetation are especially preferred. In Minnesota, this species appears fairly adaptable, utilizing a wide variety of wetland types and riverine habitats in different regions of the state. In central Minnesota, shrub wetlands are utilized throughout the summer and also serve as over-wintering sites (Piepgras and Lang 2000). In southeastern Minnesota, open marshes and bottomland wetlands provide summer and winter habitat. Ephemeral wetlands are utilized in spring and early summer, while deeper marshes and backwater pools are utilized in both the summer and winter (Hamernick 2000; Pappas et al. 2000). In southwestern Minnesota, meandering streams and rivers, fens, prairie marshes, backwaters, and oxbows are important aquatic habitats, and upland habitats include adjacent agricultural lands (Lang 2003). Female Blanding's turtles often nest in agricultural fields. This may be hazardous to both adult females and nests in the form of chemicals, disking, machinery usage, increased nest predation, and shade produced by growing crops.

  Biology / Life History

Blanding's turtles typically overwinter in muddy bottoms of deep marshes, backwater pools, ponds, and streams. They emerge from overwintering sites in late March to early April. Small, temporary wetlands are frequently used by Blanding's turtles in spring and early summer, when these habitats provide basking sites and mating opportunities (Sajwaj and Lang 2000). Shallow pools provide ideal amphibian and invertebrate breeding habitat, that in-turn provide an important food source for turtles. Aquatic vegetation, macro-invertebrates, and small fish may also be eaten (Oldfield and Moriarty 1994). Blanding's turtles have delayed maturation, reaching sexual maturity at approximately 12 years of age (Ernst et al. 1994), and females lay only 1 clutch of eggs each year. Clutch size varies widely, ranging from 10-26 eggs, with older, larger females often laying larger clutch sizes (Ernst et al. 1994; M. Linck, Three Rivers Park District, pers. comm.).

Nesting occurs in sparsely vegetated uplands with well-drained, sandy soils. Blanding's turtles often initiate nesting at dusk, although nesting after dark is not uncommon. Females may travel up to 1.6 km (1 mi.) overland from their resident marsh to their nest site (Congdon et al. 1983; Piepgras and Lang 2000). This makes them vulnerable to predators and road mortality. Hatchlings leave the nest from mid-August through early October. Because eggs are laid far from water, hatchlings often face a long overland journey after emerging from the nest. While traveling from the nest to a wetland, the hatchlings are extremely vulnerable to predators, automobiles, and desiccation. Egg and juvenile mortality is very high in this species, and nest predation has been measured at 93% (Congdon et al. 1983). Historically, this low level of juvenile recruitment has been balanced by adult longevity, as Blanding's turtles may live over 70 years (Brecke and Moriarty 1989). Today, however, the destruction and fragmentation of Blanding's turtle habitat is causing increased turtle mortality in all life stages and reductions in juvenile recruitment. Such losses can have severe and irreversible impacts, ultimately resulting in the loss of local Blanding's turtle populations.

TIME PERIOD    ACTIVITY

March-April:   Emerging from overwintering sites

April-May:      Basking

April-June:      Travel to breeding sites

April-Sept:      Travel to foraging areas

May-July:        Females travel to/from nesting sites

May-July:        Laying eggs

June-Aug:        Egg incubation (75-110 days)

Aug-Oct:         Hatchling emergence and dispersal

April-Oct:       Moving between wetlands

July-Sept:        Travel to seek drought refuge

Sept-Oct:         Travel to overwintering sites

  Conservation / Management

Efforts to delineate, protect, and restore the habitat of this species, particularly in areas that support large turtle populations, should be continued. Most of the areas with large concentrations of Blanding's turtles include some public land. Certain management activities on these lands, such as wetland drawdowns undertaken after fall, benefit other species but may negatively impact Blanding's turtles (Hall and Cuthbert 2000). In light of this, land managers should consider impacts on Blanding's turtles when managing habitat for other species. General prescribed burning guidelines have been developed for amphibians and reptiles in the Midwest, although land managers conducting burns in areas with known rare reptile or amphibian species or high concentrations of reptiles and/or amphibians may wish to contact their Regional Nongame Wildlife Specialist for input on burn planning, including timing of burns, so as to minimize impacts on these species. The use of native species should be encouraged in all habitat restoration and revegetation projects, particularly in buffer areas along rivers and streams.

Habitat fragmentation, which leads to high areas of edge habitat, should be avoided (Temple 1987). Several large Blanding's turtle populations experience high mortality each year as turtles cross roads to reach nesting sites and move between wetlands. Despite signs alerting motorists to turtle crossing areas, many turtles are still killed by cars. Additional ways to reduce turtle mortality due to cars, such as fences diverting animals into tunnels under roads, should be investigated (Lang 2000, 2001). In addition to direct road mortality, habitat fragmentation also frequently prevents turtles from accessing essential habitat components and completing their life cycle. Genetic interchange may also be limited.

  Conservation Efforts in Minnesota

In the late 1980s, the Minnesota DNR requested reports of Blanding's turtles from the public. Responses were mapped to define areas of turtle concentrations, which aided in the development of conservation priorities. The Nongame Wildlife Program subsequently delineated Priority Protection Areas for Blanding's turtles so that important areas could be incorporated into environmental review and land use planning efforts. Nongame staff are currently soliciting reports of Blanding's turtles in southern Minnesota (see flyer). Please report any sightings to the Nongame Program in New Ulm.

Several trapping and telemetry research projects have been conducted to determine survival, habitat use, and movement patterns of Blanding's turtles throughout Minnesota. These studies have aided in the development of management strategies and protection efforts for this long-lived species. Some important management issues that were identified include water-level management (Hall and Cuthbert 2000); benefits and impacts of burning upland habitats (Refsnider 2003); the use of culverts by turtles (Lang 2000); the significance of riverine habitats including ditches, streams, and large rivers (Dee 2001; Niziolek 2002); use of altered habitats such as restored wetlands (Niziolek 2002); and impacts of tree-plantings and invasive species on grasslands. Most, if not all of these studies have encountered Blanding's turtles injured or dead on roads. This continuous loss of turtles cannot be sustained long-term by Blanding's turtle populations, thereby increasing the likelihood that localized populations will be lost.

To aid developers and contractors in avoiding and minimizing impacts to this rare turtle during construction projects, the Minnesota DNR has developed a Blandings turtle fact sheet and a flyer with an illustration of the turtle. Further guidance regarding protection of Blanding's turtle nests is also available.

  References and Additional Information

Brecke, B. and J. J. Moriarty. 1989. Natural history note. Longevity. Emydoidea blandingii. Herpetological Review 20:53.

Congdon, J. D., A. E. Dunham, and R. C. van Loben Sels. 1993. Delayed sexual maturity and demographics of Blanding's Turtles (Emydoidea blandingii): implications for conservation and management of long-lived organisms. Conservation Biology 7:826-833.

Congdon, J. D., D. W. Tinkle, G. L. Breitenbach, and R. C. van Loben Sels. 1983. Nesting ecology and hatching success in the turtle Emydoidea blandingii. Herpetologica 39(4):417-429.

Dee, J. 2001. Blanding's Turtle research: 2000 Summary Report. Submitted to the Minnesota Department of Natural Resources. 3 pp.

Ernst, C. H., R. W. Barbour, and J. E. Lovich. 1994. Turtles of the United States and Canada. Smithsonian Institution Press Washington, D.C. xxxviii + 578 pp.

Hall, C. D., and F. J. Cuthbert. 2000. Impact of a controlled wetland drawdown on Blanding's Turtles in Minnesota. Chelonian Conservation and Biology 3(4):643-648.

Hamernick, M. 2000. Home ranges and habitat selection of Blanding's Turtles (Emydoidea blandingii) at the Weaver Dunes, Minnesota. MS Thesis, St. Mary's University of Minnesota, Winona, Minnesota. 18 pp.

Lang, J. W. 2000. Blanding's Turtles, roads, and culverts at Weaver Dunes. Annual report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 30 pp.

Lang, J. W. 2001. Why do turtles cross the road? Minnesota Conservation Volunteer 64(376):38-47.

Lang, J. W. 2003. Blanding's Turtle studies in southwestern Minnesota in 2002-2003. Completed under Special Permit Number 11254. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 9 pp. + illustrations.

Lang, J. W., T. Sajwaj, and S. Piepgras. 1998. Blanding's Turtle (Emydoidea blandingii) at Camp Ripley: critical habitats, population status, management guidelines. Final Report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 170 pp.

Linck, M. H., and J. J. Moriarty. 1998. The effects of habitat fragmentation on Blanding's Turtles in Minnesota. Pages 30-37 in J. J. Moriarty, and D. Jones, editors. Minnesota's amphibians and reptiles, their conservation and status: proceedings of a symposium. Serpent's Tale Natural History Book Distributors, Lanesboro, Minnesota.

Niziolek, M. 2002. Meadowvale turtle project. Elk River Area High School, Elk River, Minnesota. <http://blandingsturtles.tripod.com/main/content.html>. Accessed 17 March 2005.

Oldfield, B., and J. J. Moriarty. 1994. Amphibians and reptiles native to Minnesota. University of Minnesota Press, Minneapolis, Minnesota. 237 pp.

Pappas, M. J., B. J. Brecke, and J. D. Congdon. 2000. The Blanding's Turtle (Emydoidea blandingii) of Weaver Dunes, Minnesota. Chelonian Conservation and Biology 3(4):557-568.

Piepgras, S. A., and J. W. Lang. 2000. Spatial ecology of Blanding's Turtle in central Minnesota. Chelonian Conservation and Biology 3(4):589-601.

Refsnider, J. 2003. Population ecology and conservation genetics of Blanding's Turtles (Emydoidea blandingii) in Minnesota. Progress report submitted to the Natural Heritage and Nongame Wildlife Program, Minnesota Department of Natural Resources. 5 pp. + illustrations. Special permit 11605.

Refsnider, J. M. 2005 Reproductive Ecology of Blanding's Turtles (Emydoidea blandingii) in east-central Minnesota. MS Thesis, University of Minnesota, St. Paul, Minnesota.

Sajwaj, T. D., and J.W. Lang. 2000. Thermal ecology of Blanding's Turtle in central Minnesota. Chelonian Conservation and Biology 3(4):626-636.

Sajwaj, T. D., S. A. Piepgras, and J.W. Lang. 1998. Blanding's Turtle (Emydoidea blandingii) at Camp Ripley: critical habitats, population status, and management guidelines. Report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 185 pp.

Temple, S. A. 1987. Predation on turtle nests increases near ecological edges. Copeia 1:250-252. American Society of Ichthyologists and Herpetologists.