미국
Five-minute grid of the total marine bird biomass densities surveyed off central California - selected neutral water temperature periods, 1980-2001 (CDAS data set AL2 MASS.shp)
AL2_MASS is a polygon shapefile representing 5 minute x 5 minute latitude x longitude cells that house the overall total biomass densities (kg/sq.km.) of up to 76 species of marine birds during periods of realtively average or neutral sea surface temperatures. Density for each of 76 marine bird species was multiplied by average body mass for that species, and these products summed for all species in a cell, to obtain total biomass density. Cells that were surveyed but in which no birds were observed have total biomass densities of zero.