TY - JOUR
TI - Applying citizen-science data and mark–recapture models to estimate numbers of migrant Golden Eagles in an Important Bird Area in eastern North America
AU - Dennhardt, A
AU - Duerr, A
AU - Brandes, D
AU - Katzner, T
T2 - The Condor: Ornithological Applications
AB - Estimates of population abundance are important to wildlife management and conservation. However, it can be difficult to characterize the numbers of broadly distributed, low-density, and elusive bird species. Although Golden Eagles (Aquila chrysaetos) are rare, difficult to detect, and broadly distributed, they are concentrated during their autumn migration at monitoring sites in eastern North America. We used hawk-count data collected by citizen scientists in a virtual mark–recapture modeling analysis to estimate the numbers of Golden Eagles that migrate in autumn along Kittatinny Ridge, an Important Bird Area in Pennsylvania, USA. In order to evaluate the sensitivity of our abundance estimates to variation in eagle capture histories, we applied candidate models to 8 different sets of capture histories, constructed with or without age-class information and using known mean flight speeds ± 1, 2, 4, or 6 SE for eagles to travel between hawk-count sites. Although some abundance estimates were produced by models that poorly fitted the data (ĉ > 3.0), 2 sets of population estimates were produced by acceptably performing models (ĉ ≤ 3.0). Application of these models to count data from November, 2002–2011, suggested a mean population abundance of 1,354 ± 117 SE (range: 873–1,938). We found that Golden Eagles left the ridgeline at different rates and in different places along the route, and that typically 
DA - 2017/11//
PY - 2017
VL - 119
IS - 4
SP - 817
EP - 831
UR - http://www.bioone.org/doi/10.1650/CONDOR-16-166.1
DO - 10.1650/CONDOR-16-166.1
LA - English
KW - Raptors
KW - Birds
ER -