The 2009 Great Backyard Bird Count (GBBC) starts this Friday, February 13 and will run through Monday, February 16.

The GBBC is an annual four-day event during which bird watchers of all ages count birds, creating a snapshot image of bird populations across North America and make it as green steps.

These green steps are free, fun, easy, and open to all ages and levels of bird-watching expertise. You can count for as a little as 15 minutes on one day, or you can count as long as you like on each day of the event. All you have to do is fill out an online checklist at the Great Backyard Bird Count website.

Last year, participants submitted more than 85,000 checklists and reported more than 9.8 million birds of 635 species. As the count progresses, you can go to the website to follow what is being reported and see how the 2009 numbers compare to previous years.

The GBBC is a joint project of the Cornell Lab of Ornithology and Audubon.