The Great Backyard Bird Count takes place this weekend, February 12-15 (yes, it will be cold outside!). This joint project of the Cornell Laboratory of Ornithology and the Audubon Society involves over 100,000 volunteers and millions of individual bird lists gathered worldwide. All you have to do is register online, go outside, and count the birds you see for 15 minutes at some point over the weekend (or once or twice a day at different locations, if you prefer). Then submit your data (detailed instructions are here). The information collected helps scientists study big questions, such as the effects of climate change on bird populations.