Early Confusion

by Carl Strang

As I begin a new inquiry I usually experience an enjoyable tension. My starting assumptions begin to be contradicted by early observations, and the list of questions expands. That is my feeling these days as I begin my new study of Canada goose winter geography in DuPage County. It was prompted by my observations at Willowbrook Forest Preserve in Glen Ellyn, close to the center of the county, and at Fullersburg Woods Forest Preserve in Oak Brook at the middle of the county’s east boundary. In the early morning in winter, geese fly over Willowbrook from the southeast, heading to the nearby College of DuPage campus and Village Links Golf Course. I was curious about where they were coming from. At Fullersburg, hundreds of geese roost overnight on expanded pool areas of Salt Creek. The geese leave in the morning and fly off, generally heading northwest. Those geese vanish, however, on rare occasions when the stream freezes over (this requires subzero temperatures). When temperatures rise and Salt Creek reopens, the geese return.

 

Hidden Lake roost

Hidden Lake roost

 

So, those observations led me to wonder how many roosts and how many geese are in DuPage in the winter, and where they all go during the day. I decided to start collecting data this winter. In the first few days of this study I have found things more complicated than expected. For instance, I found that the birds that fly over Willowbrook are coming from a roost at Hidden Lake Forest Preserve, a couple miles away. But they are not all heading to the same place. On November 26 the 800 geese were departing the roost in groups of 2-40 with a rough median of 20, but heading out in various directions. Some headed northwest as expected, but many also headed southwest, west, northeast and north. Driving around in pursuit, I found them going to many destinations, generally wide open lawns, to feed. But their flights are not straight lines. Some, for instance, flew north for 2-3 miles, then abruptly changed course and headed southwest. I am pleased that this is a potentially complex study with many small discoveries in store.

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