Christmas Bird Counts

About

The data provided here are processed trends in relative abundance. Trends are available for over 500 species for a wide variety of spatial units from states and provinces to Bird Conservation Regions to nations. Trends are accompanied by the annual relative abundance indices that are used to generate the trends. These indices allow a user to calculate trends over a custom time period. Raw data from the Christmas Bird Count are available by request.

one day between December 14 through January 5 inclusively

Canada, United States, Mexico, Central America, South America, Caribbean Islands and Pacific Islands.

All birds, but coverage probably best for landbirds and waterbirds (few counts of pelagic species)

The primary objective of the Christmas Bird Count is to monitor the status and distribution of bird populations across the Western Hemisphere. The count period, which is from December 14th to January 5th, in North America is referred to as "early winter," because many birds at this time are still in the late stages of their southward migration, so it is not "true" winter. When we combine these data with other surveys such as the Breeding Bird Survey, we begin to see a clearer picture of how the continent's bird populations have changed in time and space over the past hundred years. The information is also vital for conservation. For example, local trends in bird populations can indicate habitat fragmentation or signal an immediate environmental threat, such as groundwater contamination or poisoning from improper use of pesticides.