Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (1.7 MB)

Title: Integrating citizen-science data with movement models to estimate the size of a migratory golden eagle population

Author: Dennhardt, Andrew J.; Duerr, Adam E.; Brandes, David; Katzner, Todd E.;

Date: 2015

Source: Biological Conservation 184: 68-78.

Publication Series: Scientific Journal (JRNL)

Description: Estimating population size is fundamental to conservation and management. Population size is typically estimated using survey data, computer models, or both. Some of the most extensive and often least expensive survey data are those collected by citizen-scientists. A challenge to citizen-scientists is that the vagility of many organisms can complicate data collection. As a result, animal-movement effects on data collection can adversely affect modeling of those data. Thus, it would be helpful to develop methods that integrate citizen-science datasets with models that account for animal movement. We used hawk-count data collected by citizen-scientists to estimate the number of golden eagles (Aquila chrysaetos canadensis) migrating through Pennsylvania, USA. To do this, we designed a computer model to simulate migratory flights of eagles to estimate what proportion of the population is available (i.e., within visible range or close enough) to be counted at hawk-count sites in Pennsylvania. We then conducted a multi-state mark-recapture analysis to estimate detection probability (i.e., the rate at which birds within visible range are observed) of migrating eagles. Finally, we used availability rates and detection probabilities to adjust raw hawk-count data to produce estimates of population size. Our models suggest that 24% (±14; mean ± SE) of migrating golden eagles are available to be counted at hawk-count sites, and that 55% (±1.6) of the available eagles are detected by hawk-count observers. We estimate that 5122 (±1338) golden eagles migrate annually through Pennsylvania. Our analysis provides the first quantitative estimate of the size of the eastern golden eagle population, and we demonstrate the utility of one approach to use citizen-science data to address a pressing conservation goal—population size estimation.

Keywords: Aquila chrysaetos Canadensis, Citizen-science, Golden eagle, Hawk-count data, Mark–recapture, Raptor migration

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
  • This publication may be available in hard copy. Check the Northern Research Station web site to request a printed copy of this publication.
  • Our on-line publications are scanned and captured using Adobe Acrobat. During the capture process some typographical errors may occur. Please contact Sharon Hobrla, if you notice any errors which make this publication unusable.



Dennhardt, Andrew J.; Duerr, Adam E.; Brandes, David; Katzner, Todd E. 2015. Integrating citizen-science data with movement models to estimate the size of a migratory golden eagle population. Biological Conservation 184: 68-78.


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.