The Colorado Breeding Bird Atlas II Project (Atlas II) was initiated in 2007 by the Colorado Division of Wildlife (CDOW) and the Colorado Bird Atlas Partnership (CBAP). Atlas II is a 5 year project, comprised primarily of volunteer field staff, to collect data on the distribution, abundance, habitat use, and breeding phenology of the avifauna breeding in Colorado. The first Colorado Breeding Bird Atlas was initiated in 1987, and the results were presented in the publication Colorado Breeding Bird Atlas (Kingery, editor 1998). The results of Atlas II will be compared to the results of the first Atlas and will provide information on potential changes in distribution and population status of Colorado's breeding birds. This information will be important for wildlife managers/biologists that are making decisions on land management practices throughout Colorado.

Atlas II data are being collected throughout Colorado, per U.S. Geological Survey 7.5-minute topographic quadrangle maps (quads). Each quad has been divided into halves vertically, and thirds horizontally, resulting in six equal blocks (Figure 1). The southeast (SE) portion of each quad is the Atlas II priority block for which field volunteers are first collecting data. The second priority block is the quad's central-west (CW) section, for which data may also be collected after completing the SE block.