In 1966, when scientist-student Whit Gibbons captured his first Blanding's turtle while working on his Ph.D. at Michigan State University's Kellogg Biological Station, the turtle was almost as old as he was. Finding juveniles of this species is rare but Gibbons has kept at it. Now a professor at the University of Georgia's Savannah River Ecology Laboratory and working under a grant from the Michigan Department of Natural Resources, Gibbons has found the smallest and the youngest non hatchling Blanding's turtle ever recorded. It is just two and one-half inches long and yet is four years old.
Blanding's turtles, a species of special concern in most states, are long-lived animals, some of them living to more than 75 years of age. Age is determined by examining the rings of the shell of the turtle, called "annuli." Full maturity is not reached for 15-20 years so one might think finding juveniles would be a snap. Not so, according to Gibbons, who says the difficulty comes from identifying where juvenile Blanding turtles live.
"That's what makes finding this individual so exciting," he says. Future field expeditions may be expected to locate even more juveniles now that an area has been identified as being hospitable to the young.
Gibbons has been studying the life history traits and ecology of this species under the undisturbed habitat conditions provided by the Kellogg Biological Station during most years since his graduate work at Michigan State. He spent a sabbatical year at the University of Michigan in 1975-76 and is currently an adjunct professor of zoology at Michigan State University. He has authored more than 100 scientific publications on turtles and one book on the subject. He has captured or recaptured a total of more than 30,000 turtles over the course of his research both in Michigan and at the Savannah River Ecology Laboratory.
Turtle conservation has grown in importance over the course of Gibbons' research with more species becoming threatened worldwide as turtles are being used for food, exported for trade and as their habitats are destroyed or degraded. "We are fortunate to have Dr. Kurt Buhlmann of Conservation International involved in the project as he is involved with turtle conservation issues at an international scale."
The grant, made by Michigan Natural Heritage small grants program, funded by the Natural Heritage Program through citizen contributions to the Nongame Wildlife Fund, will enable Gibbons and his collaborators to conduct field surveys of Blanding's turtles to supplement the existing 36-year data set and to examine the life history traits and ecology of the species under undisturbed conditions. Using the already-marked population in privately-owned Sherriff's Marsh in Kalamazoo County, they will also try to determine the extent to which this species uses peripheral wetlands not contiguous with Sherriff's Marsh and to find out where the juveniles live.
So far, the continuing study has yielded a treasure trove of information, with a total of 411 captures and recaptures through June 2000. Of those, 263 are different individuals. This year Gibbons recaptured three individuals he first found in 1966. Identifying marks are carved harmlessly on each individual when it is first found, allowing scientists to correctly identify it in future years. Meticulous records track where each individual is found at each capture, which gives scientists a good idea of how the species uses the available habitat. The three turtles recaptured this year are actually older than most of the scientists studying them.
Gibbons says, "The important feature of the study is that the Sherriff's Marsh habitat is one where turtle populations are thriving, compared to many populations of Blanding's turtle in other states and other parts of Michigan. What we are attempting to do is identify those environmental characteristics that make this such a healthy population of turtles. Among the most critical appear to be a landscape in which a variety of wetlands and nesting areas can be reached by turtles without their having to cross busy highways, as well as a local community that has a high respect for wildlife."
The capture of a juvenile underscores the apparent health of this population of Blanding's turtles, according to Gibbons. "Freshwater turtles are ideal indicators of environmental health. If Blanding's turtles are doing well, we can feel confident that both the aquatic and terrestrial habitats are in good shape." He said the project was made possible by the citizens who contributed to the Nongame Wildlife Fund on the Michigan income tax form or by a direct donation to the Fund.