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 Absense (Dalthorp et al. 2017).


This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.


Setup and installation require several steps. Do not skip any steps.

Updated version of R (>= 4.1.0, released May 2021):

R is free and open source software for statistical computing. If R is not installed on your computer or if your version of R is <4.1.0, download and install the latest version from https://cran.r-project.org/, following the instructions provided at the site. In particular, “Download” and then “install R for the first time” (if working in Windows), or “Download” and then follow the further instructions on the subsequent web page (if working on Mac OS or Linux-like OS). If you already have an older copy of R installed on your computer, the new version will be installed alongside the old. Unless you know a reason why you want to keep both versions, it is usually a good idea to uninstall the old version to avoid confusion and clutter.

NOTE TO EXPERIENCED R USERS: When you install a new version of R, packages that you previously installed under an older version may not be immediately available to the new R. If not, the easiest way to make them available is to copy the package folders in your old “library” folder into the “library” folder in your new R installation. Then, enter update.packages() in R. If asked about a CRAN mirror, choose the nearest location. If you are working in Windows OS and are asked whether you want to install packages “from source”, choose “No”.

Third-party packages:

Several third-party pacakges are required; all are free and open source and available from CRAN. The easiest way to install them is to run the following commands in R (with guidance concerning potential dialog boxes given below the commands):

package_req <- c("boot", "expint", "GenEst", "gpclib", "gtools", "invgamma",
"magrittr", "MASS", "matrixStats", "methods", "mvtnorm", "numDeriv", "plotrix",
"pracma", "sf", "statmod", "VGAM")

package_new <- package_req[!(package_req %in% installed.packages()[,"Package"])] 
if(length(package_new) > 0) install.packages(package_new)

– If asked about a “CRAN mirror”, choose the nearest location.

– If asked whether you want to use a “personal library”, choose “Yes”

– If you are on Windows and are asked whether you want to install packages and their dependencies “from source”, choose “No” (unless you are ready to go to lunch, in which case, you can select “Yes” and the installation may well be done by the time you get back).


Click on “Tags” under the “Repository” tab on the left sidebar at https://code.usgs.gov/ecosystems/dwp and then click the link for the specific release you want.

– For Windows, download the compressed folder dwp_1.x.x.zip (do not unzip) and note where it is stored. You will install from the local .zip folder.

– For Mac OS or Unix-like OS, download the compressed file dwp_1.x.x.tar.gz and note where it is stored. You will install from the local .tar.gz file.

If you are working directly in R (not R Studio), run the following command:

install.packages(file.choose()) # and navigate to the package archive file you just downloaded: dwp_1.x.x.xxx

If you are working in R Studio:

Click “Install” in the Packages pane.

Select “Package Archive File (.zip; .tar.gz)” as “Install from:” in the dialog box.

Browse to where you saved the zip file, and open it so it appears in the Package archive” space.

Click the Install button on the dialog box.

Getting Started

Download the User Guide from <??? we have it but it has to go through the copy editor. With GenEst, we had a copy of the pre-final (i.e., version sent to the copy editor for formatting and style) but approved copy of the user guide posted at code.usgs.gov and then later linked to the T&M docs after they made it through Tacoma.>

In R, type the following commands for an overview of the main commands in the package:


Help files for dwp functions are accessible in the standard R way, for example:


Further Reading

dwp User Guide: <in press…can we put a temp copy up at code.usgs.gov?>

Dalthorp, D, Simonis, J, Madsen, L, Huso, M, Rabie, P, Mintz, J, Wolpert, R, Studyvin, J, and Korner-Nievergelt, F. 2018. Generalized Mortality Estimator. R package version 1.4.6. https://CRAN.R-project.org/package=GenEst

Dalthorp, D, Huso, M, Dail, D, and Kenyon, J. 2017. Evidence of Absence (v2.0) Software and user Guide. https://pubs.er.usgs.gov/publication/ds1055