People from all walks of life will don binoculars, if they can find them, and trek outside this weekend to count birds ranging from finches to juncos for 15 minutes as part of the Great Backyard Bird Count.

In its 10th year, the project relies on participants to create a long-term record of changes in the distribution of bird species. The idea is to generate information about how environmental changes affect birds.

To take part, participants simply head out to a backyard, local park, wildlife refuge or other outdoor area and tally up each bird species spotted in one location over at least 15 minutes any time between Feb. 16 and Feb. 19. Counts can be submitted online at: birdcount.org.

Tally tips

Record only the highest number of individual birds of each species that you see together at any one time. For instance, if you spot a flock of red finches a few times within 15 minutes—first you might see three birds, then two and finally one—jot down the greatest number.For large flocks, count the birds in a small section of the flock. Then, multiply that number by the number of parts of similar size that could fit into the entire flock.To distinguish between some similar-looking species, go to birdsource.org.Numbers add up

Last year, backyard counters reported more than 7.5 million birds, including 622 different species.

“The Great Backyard Bird Count— which is carried out over a short but intense period of time—provides a nice snapshot on the winter distributions of birds,” said Janis Dickinson of the Cornell Lab of Ornithology. “If we examine these data over time, we can observe the possible range shifts that are occurring.”

As the climate changes, the scientists involved in the count say bird habitats could also change. “Counting which birds are where each year is an important way to track the effects of climate change on birds over time,” said Paul Green of the National Audubon Society.

Images: Birds of PreyImages: Rare and Exotic BirdsTop 10 Species Success StoriesVideo: Extraordinary BirdsVideo: How a Songbird Sings