Estimating the number of birds or bats killed at a wind power facility involves adjusting observed carcass counts to account for imperfect detection. To account for carcasses that lie outside the searched area, the count is adjusted by dividing by the estimated proportion of carcasses lying within the searched area or the density-weighted proportion (dwp). The dwp package provides tools for estimating dwp for use in mortality estimators such as GenEst (Dalthorp et al. 2018) and Evidence of Absence (Dalthorp et al. 2017).