Wednesday, October 12, 2011

Foot prints

How can biologists efficiently collect enough observations to draw conclusions about mammal abundance or diversity in a habitat? This is exactly the problem my students and I tackled in the Saint Michael's College Community Ecology course in the last two weeks. Attempting to observe shy mammals can be disappointing, particularly when moving through a habitat as a group of 20. Instead, our approach was to record mammal footprints at track stations.

Our track stations included a layer of powdered black chalk to blacken the feet of the mammals and a sheet of sticky contact paper to collect each chalky print. All of this was sheltered from rain in a plastic tunnel-shaped structure with an opening at one end. Students determined which habitats to study and we left several track stations in each habitat. We convinced the mammals that walking through chalk and onto contact paper was a good idea by baiting the stations with peanut butter or dog biscuits.

We recorded a total of 355 visits to our 31 track stations over a two week period. We have indeed confirmed that the campus is a grey squirrel and chipmunk haven! Prints were also left by skunks, raccoons, muskrats, and mice. One of the stations with rather smudged prints also contained several black hairs. Microscopic scale patterns on the hairs confirmed our suspicions that the nocturnal visitor was a skunk. Perhaps most interesting, the traps set by the Winooski River were visited by mink; perhaps many mink, or perhaps just one extremely well fed mink with a deep fondness for peanut butter and dog biscuits.

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