This year's annual 115th Christmas Bird Count (CBC) began on Sunday, December 14 and will continue till January 5. Initially, the CBC sponsored by the Audubon Society and Cornell University was started on Christmas Day. But now, it continues for weeks.

These surveys are quite important due to many reasons. One of the main reasons is that the yearly surveys provide information about the changes in bird populations that place over the time. Loss of habitat, serious environmental threats like groundwater contamination or improper use of pesticides can be known through the surveys.

The survey results have helped track the introduction of foreign species like the Eurasian Collard Dove and expansion or relocation of bird ranges across America. The bird counts also show the reaction of bird populations to natural occurrences like droughts, changing temperatures and other factors.

Many birds are adapting according to urban habitats, but there are many other species that are declining as cities are expanding into countryside. West Nile Virus has impacted species like crows, jays, owls and some raptors.

The Christmas Bird Count is the longest running survey, which was started on Christmas Day to replace a hunting tradition. Frank Chapman, an ornithologist at the American Museum of Natural History and early officer the new Audubon Society, were the ones who suggested counting birds during holidays rather than hunting them.

With passage of time, number of volunteers has increased tremendously. This year, 70,000 volunteer counters are expected to take part at more than 2,400 locations from Arctic Circle to the southern-most tip of South America. If the number is compared from the time when the count started, the number is quite significant. Bird counts take place at different places each year.