Sunday, July 22, 2007

Little stinkies

Weighing in at an average 170 grams with a 4 inch long carapace (though highly variable throughout their range), stinkpot turtles are the smallest turtles in Missouri and one of the smallest turtles in the world. Stinkpots (Sternotherus odoratus, also known as common musk turtle) belong to the family Kinosternidae, which is represented by 25 species of four genera found only in the New World. Underneath the carapace near the back legs are musk glands that excrete a relatively foul-smelling musk when the animal senses danger. Hence the name "stinkpot."
Stinkpots are found throughout the eastern United States from Texas to Wisconsin and east through New England, northern Ontario and down to Florida. They are listed as rare in Iowa. Because stinkpots are so widespread, their sizes range from 2 to 4.5 in. long, with the largest on record measuring 5 3/8 in. Stinkpots are seldom seen because they spend most of their lives in water, generally coming on land to lay their eggs and to search for available habitat. Unlike red-eared sliders and many other species of freshwater turtles, stinkpots aren't very often seen basking on logs.

Where populations exist, stinkpots are generally abundant. They make up a significant portion of an area's biomass. Studies suggest that on average, 100-200 individuals live in a single hectare. My herpetologist, Bones, studied stinkpots at a slough in nearby Reelfoot Lake for his Master's thesis. He discovered a population density of 984 individuals/hectare, which translates into roughly 101 kg. of stinkpots/hectare. The great pictures, by the way, are from Bones' vast collection of wildlife pictures.

Permanent swamps, sloughs and slow moving portions of rivers are required habitat for stinkpots. They prefer areas with vegetative debris where they feed primarily on crayfish, aquatic insects, fish eggs, minnows, and algae. Bones and I are 6 weeks into the turtle survey and have found only 17 stinkpots in the park (and almost 600 red-eared sliders). The low number of stinkpots is somewhat surprising, considering our proximity to Reelfoot Lake. The park's hydrology has been so drastically altered to assist in the drainage of adjacent farmland that areas that should have permanent water dry up each summer. Bones suggests that as stinkpots move throughout the park in search of permanent water, they become easy prey. Their small size makes them vulnerable to large raptors like eagles, who managed to pluck off at least 30 individuals last winter, leaving a collection of stinkpot shells under their massive nest.
With the park's hydrology restoration project beginning this fall, there may be hope for stinkpot populations. Our turtle survey is lacking several species that should be in southeast Missouri and probably were before the drainage projects began. Population estimates for southeast Missouri endemics like stinkpots, cooters, false map turtles and Southern painted turtles are abysmally low considering the same populations at places like Reelfoot Lake. The drainage of the area's swamps, sloughs and backwater habitat may have been too drastic for certain animals like the state endangered Western chicken turtle to deal with.

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