Thursday, September 04, 2008

UI student studies fox snakes at Allerton to inform management decisions about natural areas

UI student studies fox snakes at Allerton to inform management decisions about natural areas

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Most people who visit the U of I’s Robert Allerton Park near Monticello seeking to connect with nature go to enjoy the beauty of the woodland wildflowers in spring or the colors of the changing leaves in Fall. Others may enjoy opportunities for watching birds, or participate in the fall hunt to manage and study the deer herd.

Few people go to Allerton to look for snakes, though, or even care whether they are present there. That’s definitely not the case with John Griesbaum, a University of Illinois student who is working toward a Master’s degree in the Department of Natural Resources and Environmental Sciences. Under the direction of Chris Phillips, a herpetologist with the Illinois Natural History Survey and U of I faculty affiliate, Griesbaum is studying how the management of natural areas at Allerton affects one species of snake that inhabits them, the western fox snake. The goal of his research is to provide information to managers of natural areas about how practices such as prescribed burning, mowing, and brush removal affect the well-being of individual snakes and the overall health of snake populations.

Why should anyone care about how well fox snakes are doing? Griesbaum provides two answers. One is simply that fox snakes are part of the natural heritage of Illinois, and ought to be conserved for all of the same reasons we ought to conserve other plants and animals. The other is that snakes constitute an important middle link in a grassland food chain, controlling the abundance of the small rodents on which they feed, and serving as a source of food for the larger mammals and birds of prey that feed on them.

Between April and July of this year Griesbaum captured 11 fox snakes that were large enough to be included in his study. [Photo: A fox snake with radio transmitter implanted is ready for release.] Each of these snakes had a tiny radio transmitter implanted under its skin, thanks to veterinarians with the University of Illinois Wildlife Medical Clinic. The snakes were then released back where they had been captured.

That’s when the real legwork for the researcher began.

Griesbaum’s study requires that he locate each snake every other day for one year after its release, which he does by means of a handheld antenna and radio receiver. This can be trickier than you would think if you’ve only seen it done on T.V. Fox snakes move through tallgrass prairie reconstructions and forest edges much more easily than people do, and they don’t simply slither across the ground. [Photo: Griesbaum tracks a snake from his study in the main tallgrass prairie reconstruction at Allerton.] On a day in late July when I accompanied Griesbaum in the field we searched long and hard for snake #5 even after the beeping receiver told us we were right on top of it; it had taken refuge in a burrow underground. That same day we located snake #11 well above the ground—six feet up in the hollow trunk of a small tree.

When Griesbaum catches up with a snake he records its location as a point on a map and then collects a suite of data about what it is doing and the habitat it is using, whether, for example, it is basking in the grass or on the move through the woods.

Ultimately he will use this data to describe the home range and habitat preferences of western fox snakes at Allerton, and characterize their patterns of movement. Such information will help land managers adapt their practices to better maintain the full character of natural areas, at Allerton and elsewhere.