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If you’ve ever seen a snapping turtle in Illinois,
it was almost certainly a “common snapping turtle.” Common snappers can be
found throughout the state, and they’re able to adjust to life in nearly any
body of water. This commentary is not about common snapping turtles. It’s about
alligator snapping turtles, which are
bigger, gnarlier southern cousins of common snapping turtles.
Alligator snappers are distinguished by three ridges of spines on their
upper shell and a head that looks huge in proportion to their body. They also
have a wicked hooked beak. And they get big, too, bigger than any other
freshwater turtle in North America, with top weights in the wild reaching 155
pounds.
[Photo by Eva Kwiatek. Ethan Kessler draws blood from an alligator snapping turtle just before releasing it.]
Alligator snappers prefer life in large rivers like the Mississippi,
Ohio and Wabash or waters directly connected to them. So they were never
widespread in Illinois, which also marks the northern limit of their range. Over
the course of the twentieth century, alligator snapping turtle populations in the state were
wiped out entirely by habitat alteration and overharvesting. But favorable
conditions now exist in enough places to make reintroducing them feasible.
I spoke recently about a project to do just that with two of the people
at its forefront, Mike Dreslik, a herpetologist with Illinois Natural History Survey (INHS) in Champaign, and Ethan Kessler, who is working toward a master’s degree in the Department of Natural Resources and Environmental Sciences at the U of I, with Dreslik as his adviser. Here’s what I learned from them.
The current reintroduction, which involves collaboration with multiple
other state and federal agencies, as well as the St. Louis and Peoria zoos,
involves a long-term effort. That’s because alligator snapping turtles are
long-lived creatures, and they don’t reach sexual maturity until they’re 11 or
more years old.
This summer Dreslik, Kessler and others released a
total of 97 alligator snapping turtles in a creek at the southwestern edge of
the state. To say those turtles were released, though, tells only a small piece
of the story. On the day they were let go, every one got a health checkup,
which included a visual exam and blood work. They were also fitted with tiny
data loggers that record water temperature, and 62 them had radio transmitters
attached to their shells.
With the help of those transmitters, Kessler and
company relocated each turtle three times a week through the rest of the field
season. Partly this was to keep tabs on the health of the turtles and to see whether
they were competent at life in the wild, since nearly all of them were reared
in aquariums at hatcheries or zoos. Happily, they really were and only one of
the turtles with a radio transmitter died this year.
Additionally, the information gathered in
relocating them will help scientists answer important questions about habitat
preferences and movements. The surprise on this front came from the biggest of
the released turtles, a 16-pounder. He immediately moved nearly a mile upstream
to a big logjam, where he then stayed put for the rest of the season.
The answers to questions about movements and
habitat preference will, in turn, help to answer a broader one, which has
implications for the prospects of other endangered turtle species as well. As
Dreslik summed it up, “How do we reintroduce turtles to the wild with the
greatest chance of success?”
For now, though, the more pressing concern about
Illinois’ new alligator snappers is how well they cope with winter. We’ll check
back next spring to see.
Bonus turtle
Explaining this as part of the radio commentary got too convoluted so I left it out there. But INHS herpetologist Chris Phillips came up with a real surprise as he was groping around in deep, murky water to find one of the turtles with a radio transmitter; he found a wild alligator snapping turtle, the first one in the state since 1984.
[Phillips (left), Kessler and native Illinois alligator snapper. Photo by Mike Dreslik.]
As to what exactly that means, the jury is still out. But given the amount of time and effort that has gone into looking for alligator snapping turtles, no one I spoke with was inclined to take it as evidence of some hidden, viable population.
As to what exactly that means, the jury is still out. But given the amount of time and effort that has gone into looking for alligator snapping turtles, no one I spoke with was inclined to take it as evidence of some hidden, viable population.
