So you have this bird that's up in the top in the most numerous birds that wasn't even here 120 years ago, until people decided to introduce them to New York's Central Park, because they wanted all of the birds Shakespeare had mentioned to be in the United States.

Miyoko Chu, is a science editor at Cornell University's Lab of Ornithology, and she joins us from Ithaca, New York.

Dr. CHU: You can absolutely do that. And you can do it anywhere, whether it's your backyard or a local park. And yes, you count the birds that you see and you tally the highest number that you see at any one time of each species. And then you go to the Web site and you put in your tallies. And they will zip over and help create a real time picture of where birds are at your location and across the continent.

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HANSEN: Is there one bird that kind of tops the list of the tallies?

Dr. CHU: The thing about bird populations is that they're constantly in flux. And it's really a challenge for scientists to track changes in hundreds of bird species across the continent. You can well imagine. But last year, for example, participants counted seven and a half million birds of 622 different species, which is a massive amount of information in a short amount of time. And each of those species they reported has its own story. So just for example, over the last 10 years, people have contributed to pictures of migration, like of sand hill cranes on their migration flyways. And they have made it farther distances north depending on the weather conditions that year.

This Friday, February 16th, the 10th Annual Great Backyard Bird Count begins. The count ends Monday, February 19th.

´╗┐Backyard Bird Count Enters Tenth Year

HANSEN: First, how does this work? Do I just go out into my backyard and if I see, say, four cardinals and six geese and two blue jays and a pigeon, I just write it down and send it to the site? I don't need anything special?

HANSEN: Are you seeing interesting patterns, and patterns changing over the past 10 years?

Dr. CHU: Well, last year Buy Men Canada Goose Chateau Parka Brown Online the Canada goose was the most numerous bird reported, followed by the snow goose and the European starling. And what's interesting about the European starling is that about 120 years ago, had this count been occurring, you would have had zero.