Common birds becoming less common

Some of the most common birds seen and heard in American back yards are becoming a less frequent sight and sound in much of the United States, according to a study released by the National Audubon Society.

Link: http://rss.cnn.com/~r/rss/cnn_space/~3/124903301/index.html

Time: 14. Jun. 2007

Feed: CNN.com - Science & Space

Topics: becoming, birds, common, common, less