June 17, 2007

Disappearing Backyard Birds


The National Audubon Society has been sponsoring Citizen Science (pdf) projects designed to have the people all over the country provide data that can track the health and frequency of birds over a span of years. The oldest of them is the Christmas Bird Count which I've written about here. Then over the President's Day weekend in late winter, Audubon asks people to participate in the Great Backyard Bird Count (pdf) with a count of all the birds -- both species and the number of each species -- they observed coming to their backyard feeders. Finally, working with the Cornell Ornithology Lab, they've provided the online eBird site where birders can add their sightings throughout the year into a collaborative database. All these actions have provided much better information about bird populations in the United States.

Now with more powerful data-mining tools, scientists can analyze the data to see what is happening with birds across the United States. This week, Audubon released a report that warned many of the common backyard birds we've known are starting to become severely stressed and we can see this in the collapse of their populations. The culprits leading to their declines are loss of habitat due to sprawl, global warming and other invasive species that are out competing them in their nesting or wintering grounds.

Twenty different common bird species those with populations more than half a million and covering a wide range have seen populations fall at least in half since 1967, according to a study by the National Audubon Society. The bird group compared databases for 550 species from two different bird surveys: its own Christmas bird count and the U.S. Geological Survey's breeding bird survey in June.

Some of the birds, such as the evening grosbeak, used to be so plentiful that people would complain about how they crowded bird-feeders and finished off 50-pound sacks of sunflower seeds in just a couple days. But the colorful and gregarious grosbeak's numbers have plummeted 78 percent in the past 40 years.

"It was an amazing phenomena all through the '70s that's just disappeared. It's just a really dramatic thing because it was in people's back yards and (now) it's not in people's back yards," said study author Greg Butcher, Audubon's bird conservation director.

Some of the birds that are losing ground are the state birds for a number of states such as the Eastern Meadowlark. What happens when they are gone? What a bleak world it would be without the songs and vibrant colors of so many of these birds.

Posted by Mary at June 17, 2007 06:16 PM | Science | Technorati links |