Description: The identification of core population areas is intended to capture all seasonal requirements for greater sage-grouse; however there is recognition that in some cases core population areas may not capture all annual greater sage-grouse needs. Specifically, winter concentration areas, defined as places where large numbers of core population area greater sage-grouse congregate and persistently occupy between December 1 and March 14, should be identified and protected. Identification of winter concentration areas should be based on habitat features and repeated observations of winter use by biologically significant numbers of sage-grouse using a validated Resource Selection Function (RSF) modeling approach.