Tally 'em up: annual Christmas bird count.

• Position: Audubon Society

Now in its 116th year, the National Audubon Society's annual Christmas Bird Count will take place Dec. 14Jan. 5, 2016. More than 72,000 volunteers from 2,400-plus locations across the Western Hemisphere record sightings of bird species, with the data collected and submitted to Audubon for research on bird populations and environmental conditions.

Each winter, citizen scientists gather in 15-mile-wide circles--organized by a count compiler--and tally every bird they see or hear. This provides valuable insights Into population trends for many species that otherwise would go undocumented.

"New tools--including apps, smartphones, and map-based technologies--are making it easier than ever for anyone to be a citizen scientist," says David Yarnold, president and CEO. "People who watch birds are seeing changes. By recording all those observations, they're contributing the information that's needed to make a difference."

To date, more than 200 peer-reviewed articles have resulted from analysis done with Christmas Bird Count data. These efforts also are critical to understanding how birds are responding to a changing climate. This documentation Is what enabled Audubon scientists to discover that 314 species of North American birds are threatened by global warming.

Last year's count shattered records, as 2,462 counts and 72,653 observers tallied more than 68,000,000 birds of 2,106 different species. Counts took place in all U.S. states and Canadian provinces, as well as over 100 count circles in Latin...