White-throated Sparrow by Gary Mueller/PFW

We’ve said many times that entering data into our eBird program is a great way to make your hobby count toward something bigger. Now a paper in the journal Public Library of Science Biology (PLoS) says so, too.

The report describes eBird, a nine-year-old project by the Cornell Lab of Ornithology and Audubon, as an example for researchers interested in the power of human computation—tapping the human brain to do things that computers can’t yet do. For eBird that task is identifying birds, but other projects involve identifying galaxies, deducing the folded structures of proteins, and digitizing books one word at a time.

The paper’s authors—all members of the Cornell Lab’s Information Science program—discuss how eBird has succeeded in recruiting a volunteer workforce. They stress the importance of knowing their audience, offering tools (such as personal checklists and sightings maps) that give back to the user, and devising ways to ensure data quality without making data entry onerous. The reward for successfully balancing these concerns has been the emergence of a vibrant community of eBirders and the immense, global database of observations they have built.

One way those data have begun bearing fruit is in the form of a new kind of range map—one that moves before your eyes. eBird’s new animated occurrence maps statistically model a species’ occurrence across North America for each week of the year—in essence producing 52 separate range maps for each species. By flashing them on your computer screen in sequence, you can watch a species ebb and flow over the continent.

As an example, consider the White-throated Sparrow. Field guides tell you these handsome little sparrows winter in the East and move northward in summer. But we’re basically left to guess about the routes and timing of migration. The figure at right shows three excerpts from an animated occurrence map. Shading corresponds to the likelihood of occurrence—another difference over typical range maps. The first map shows how the birds start the year mainly in low-elevation parts of the East. By May they are moving north, mainly through Minnesota and Michigan but also in Wisconsin and New England. By early June they’re almost all gone from the United States. When will they return? See the full 52- map animation here.

Watching these new maps change as a year sweeps past can be as mesmerizing as it is informative (see maps for 50 common species here). Just remember to keep birding and to enter your own data into eBird, where your contributions can take shape right before your eyes.