These dynamic maps are separate from but in support of the baseline risk maps produced by provincial government agencies, using standardized surveys of breeding populations the previous year (population trends and survey methods were analyzed, assessed and adapted to GIS methods by Johnson [13,14] and Johnson and Worobec [15] and by subsequent researchers in other provinces and states). Grasshopper degree-day models in the US typically use lower temperature thresholds of more than 17 C, but we have found soil thresholds of 12 C and air temperature thresholds of 15 C more accurately reflect development.