MICHIGAN’S TURTLES An Ancient Lifestyle vs Modern Threats Of the roughly 300 species of turtles and tortoises world- wide, only 10 are found in the wild in Michigan…

Not really too bad for a “northern” state… Turtles are most diverse in the southern and western parts of the lower peninsula. Recent research confirms that turtle success depends on an important biological characteristic— extreme LONGEVITY.

An “average” turtle can live at least several decades, while many species are known to surpass the century mark.

Eastern Box Turtle Longevity is necessary, to make up for the “normal” massive mortality of turtle’s eggs and hatchlings, as well as the typically long time periods needed for young turtles to reach sexual maturity.

Predated nest (probably by raccoon)

Raccoon predating snapping turtle eggs as they are laid…

Courtesy Ron Brooks The chances of any one hatchling turtle reaching maturity are extremely small!! But the turtle population can remain stable as long as the adults can last long enough to replace themselves— which might take 50 years for a Blanding’s or Wood Turtle… The most important thing to remember about turtles is not that they CAN live very long lives— It’s that they MUST live long lives!! Human activities and environmental changes have thrown up numerous roadblocks for turtles in recent decades… • Habitat destruction and degradation. • Water pollution (species vary in tolerance). • Road mortality (hit females harder?). • Harvest and collection (food, pet trade, plinking, etc. Sustainable harvest doubtful). • Human-subsidized predators (coyotes, skunks, possums, but mostly RACCOONS).

Snapping Turtle (Chelydra serpentina) Largest MI turtle— thus preferred for human consumption… Snappers: • Are the largest turtles in Michigan (up to 20 inch carapace length and 50 pounds+). • Widely distributed, live in most aquatic habitats (lakes, ponds, rivers, etc.) statewide. • Eat a wide variety of animal and plant foods. • Tolerate fairly polluted waters (but accumulate toxins). • Do not, under most circumstances, have a significant effect on waterfowl or game fish populations. • Are dangerous only when harassed out of water, or restrained underwater. • Commercial harvest curtailed in 2008; subject to review. • Personal take subject to season, size & bag limits. Subject to same limitations as other species; can remain viable if not subject to concentrated harvest…

Aided by wide tolerances and large clutch size; vulnerable during winter dormancy and nesting. Depleted populations will be slow to recover after exploitation. Common Musk Turtle (Sternotherus odoratus) Musk Turtles: • are one of the smallest turtles in Michigan (up to 5.4”) • prefer to live in clear lakes, larger ponds, and slow- moving rivers, with some bottom vegetation and sand or marl substrate; found only in Lower Peninsula. • eat small aquatic insects, snails, crayfish, etc. • are often nocturnal in summer. • are threatened by rampant lakeshore development and use of aquatic pesticides.

• No population data, but clearly subject to decline or extirpation in developed lakes. Musk turtles lay hard-shelled eggs— and can be sloppy nesters, though some females make a “normal” nest.

Normal, buried nest

Exposed nest, eggs barely concealed Spotted Turtle (Clemmys guttata) Probably most threatened Michigan species Spotted Turtles: • Are one of the smallest turtles (maximum 5.4 inches). • Live in specialized bog and fen type habitats; shallow water; Lower Peninsula only. • Eat mostly small insects, mollusks, worms, some fruit. • Are listed as THREATENED (protected) in Michigan; they are rare due to loss of habitat and exploitation for the commercial pet trade. Some level of protection over most of range.

• Very low fecundity, low clutch size. In Michigan, most closely associated with shallow fens habitats with sphagnum moss, sedges.

Ongoing research: Wood Turtle (Glyptemys insculpta) 1969—2009 A truly superior animal with a dim future… Wood Turtles: • Reach a length of about 9 inches. Maturity reached at about 6 inches, in 13 to 20 years. • Occur in or near streams and rivers, usually sand or gravel substrate; forage in adjoining woods and fields. Upper and northern Lower Peninsula. • Omnivorous— eat berries, fruits, some vegetation, earthworms, slugs, insects, occasionally carrion. • “Special concern” in Michigan (protected); rare and declining rangewide due to illegal collection, predation by over- abundant raccoons, road mortality, habitat destruction.

• Life history very similar to the Blanding’s Turtle— but perhaps even more vulnerable.

Many populations of Wood Turtles appear to be “ghost populations.”

As defined by Compton, these are populations made up of mostly older adult animals, with insufficient juvenile recruitment to replace gradual losses of adults— thus doomed to eventual extirpation. Ghost populations may appear superficially healthy during surveys, despite being non- viable. Blanding’s Turtle (Emydoidea blandingii) Best studied of Michigan’s turtles…

Plastron has hinge, but flexibility is variable… Blanding’s Turtle: • Reaches a carapace length of 10.8 inches. May take 15 to 20 years to mature; lives to at least 90 years+. • Prefers marshy habitat with small ponds or weedy shallows along lake shores; found in both peninsulas but rare in UP. • Carnivorous; eats crayfish, minnows, worms, insects. Feeds in water only; stalks prey at night in summer. • “Special concern” in Michigan (protected); rare to endangered over much of range.

Habitat loss and pollution are threats; many are killed on highways (MAJOR THREAT). Classic studies in Michigan set the stage for a new turtle conservation paradigm. Eastern Box Turtle (Terrapene carolina carolina) Named for ability to completely close up using plastral hinge

Note “helmet- shaped” carapace, prominent growth annuli. Color highly variable… Eastern Box Turtles: • Are small, reaching max. 7.2 inches (but rarely exceed 6 in.). Matures in about 10 to 15 years, can live to 100+ years. • Prefer rolling woodlands and woods edges, nearby meadows and marshes. Use shallow ponds in hot weather. Our only mostly terrestrial turtle. West & southern Lower Peninsula. • Omnivorous: eats berries, fruits, mushrooms, insects, worms, slugs, occasional carrion and vertebrates. • Listed as “special concern” in Michigan (protected). Threatened by road mortality, habitat loss, illegal collection.

Once exploited for international pet trade, but now listed as CITES II. Classic example of population dependence on longevity of mature adults. Painted Turtle (Chrysemys picta) Midland Painted over most of state (LP and eastern UP).

Western Painted, with colorful plastron, enters the western UP, where the two subspecies interbreed. Painted Turtles: • Small, to 7 inches; western type gets bigger. • Most common turtle in MI; all still waters (ponds, lakes, backwaters, marshes, etc); state-wide. • Eat aquatic plants and various aquatic invertebrates (insects, crayfish, mollusks, etc.), small vertebrates (tadpoles, minnows), and carrion. • Not state listed, remains common in many areas, but pollution, habitat loss, and road mortality are constant threats.

• May benefit from dispersed nesting habits. Note: Hatchlings may remain in the underground nest all winter; have tolerance to freezing temperatures.

Eggs laid in June, hatch in August, but young don’t emerge until following May!

Adults cannot freeze though— must hibernate under water. Red-eared Slider (Trachemys scripta elegans) Adults and juveniles have a dark olive to brown carapace, often marked with yellow streaks…

Hatchlings are mostly green— but most specimens have the orange-red streak behind the eye. Familiar in the pet trade— especially to “boomers.” Red-eared Sliders: • Are a bit larger than Painted Turtles, females reach 11.4 inches. No red stripes on legs as in Painteds. • Found in same aquatic habitats as Painteds, but adults may use deeper waters. Occur in scattered localities around southern Lower Peninsula. • Colonies in Michigan MAY have largely originated with pet trade releases, but Sliders were present in MI over 2000 years ago, so can be considered native to the state. • Eat both plant and animal foods; adults eat more plants than young ones. • Common in some parts of its wide range, but exploitation and habitat destruction have reduced numbers in some areas. Sliders now occur all over the world, due to commercial trade. Northern Map Turtle (Graptemys geographica) Sometimes confused with Painted Turtle, but Map Turtles lack any red striping on head, neck, or limbs. Northern Map Turtles usually have a small yellow blotch behind the eye.

Females are larger than males, and have wider heads. Northern Map Turtles: • Males reach only 6.3 inches carapace length; females can reach 10.7 inches. Males mature in 3 to 5 years; females take 10 to 14 years. • Found over most of Lower Peninsula; has been reported in the UP, but is rare up north. Mostly seen in larger, slow- moving rivers and larger, clear lakes. • Males and young females eat mostly aquatic insects and very small mollusks; large females can crush large snails and clams, and will eat zebra mussels. • Not listed in MI; locally common in the right habitat. Declining where lake shore development has reduced nesting habitat and aquatic plants and mollusks. As in most turtles, the sex of hatchlings is temperature dependent…

But also as in most turtles, the vast majority of eggs are destroyed by predators before hatching. One year old Map Turtle Eastern Spiny Softshell Turtle (Apalone spinifera) Note flat oval to round carapace, lacking scutes, soft at edges. Fully webbed feet, and “pig-like” nose (used like a snorkel). Spiny Softshells: • May reach 19 inches long— but only the females. Males are smaller (maximum about 9 inches). • Fully aquatic, living in deeper lakes and rivers with open sand or mud bottom. Lower Peninsula only. • Eat crayfish, aquatic insects, occasional small fish or tadpoles. Food often ambushed from concealment. • Populations have declined due to pollution, exploitation, and development of lakeshore habitat, which eliminates critical nesting areas. Michigan regulates with season, possession limits. This species is often killed by rotenone fish surveys.

• Collision with boats and PWC is common cause of mortality. Require nest sites adjacent to water…

Hatchlings must be able to go directly to water. Master of concealment— but one of the fastest vertebrates in fresh water! After 220 millions years of success, humans and human activities now threaten over two-thirds of all turtle species. It’s time to give turtles a break (and a brake)!!