"Is the wedge of Canada Geese flying southwest over my house headed back to Cayuga Lake for the night or is it migrating south for the winter?"
"Is it normal for there to be so many robins around this time of year?"
"Is the Evening Grosbeak at my feeder an indication that the finches may be irrupting southward from the their normal wintering grounds in the north?"
We are addressing questions such as these by gathering observations from individual bird-watchers all over the continent and examining maps of the distrbutions using Geographical Information Systems (GIS). This approach is the basis of the BirdSource web site, managed by the Cornell Lab of Ornithology and the National Audubon Society. Using data from BirdSource, bird population movements are mapped and presented on this site.