This data set is an intersection of all 63 vector polygon ranges depicted in the following publication with a statewide grid of 25 square mile hexagon cells. Shuford, W.D., and Gardali, T., editors. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game. Sacramento. http://www.dfg.ca.gov/wildlife/species/ssc/birds.html The vector polygon ranges were hand drawn at a scale of 1:6,600,000 by authors and editors of the Bird Species of Special Concern report and digitized into shapefiles by staff of the Biogeographic Data Branch, California Department of Fish and Game. The hexagon grid for the state was created by Steve Goldman by modifying an AML (Arc Macro Language) script originally written by Eric Kauffman.