Recent changes in climatic conditions and concomitant urbanizations have led to several species shifting their geographic ranges. Species distribution models (SDMs) are now the primary tool used to predict the geographic distribution of plants, animals, and other biogeographic phenomena in current and future geographic space. Identifying whether a geographic area is climatically suitable and accessible, or climatically suitable and inaccessible has become an important research topic in SDM. We have identified 20 methods of incorporating migration alongside SDM to predict range shifts, and assess them for their accuracy in predicting future distributions, as well as the uncertainty between predictions. Bird atlas data from Great Britain from 1988-1991 was used, and relationships with climate and habitat extrapolated to current time, with the 2007-2011 atlas used to test the accuracy of three SDMs and 20 migration methods for 50 bird species. Differences in projected ranges among the migration methods, e.g., a difference in area of 64km2 for two fixed rate models was identified for the native Cetti’s warbler, indicate the magnitude of uncertainty. Ensemble models (generated by combining multiple projection outcomes) were created for each species, and a new index was developed to quantify uncertainty among the projections. Values ranged from 0.697 (large areas of disagreement and high uncertainty) to 0.999 (large areas of agreement and low uncertainty). This index will allow researchers to quickly identify high or low uncertainty amongst projection results from migration methods and discuss future range shifts.