Assessment of Frequency and Duration of Point Counts When Surveying for Golden Eagle Presence

We assessed the utility of the recommended golden eagle (Aquila chrysaetos) surveymethodology in the U.S. Fish and Wildlife Service 2013 Eagle Conservation Plan Guidance. We conducted800-m radius, 1-hr point-count surveys broken into 20-min segments, during 2 sampling periods in 3 areaswithin the Intermountain West of the United States over 2 consecutive breeding seasons during 2012 and2013. Our goal was to measure the influence of different survey time intervals and sampling periods ondetectability and use estimates of golden eagles among different locations. Our results suggest that a lessintensive effort (i.e., survey duration shorter than 1 hr and point-count survey radii smaller than 800 m)would likely be inadequate for rigorous documentation of golden eagle occurrence pre- or postconstruction ofwind energy facilities. Results from a simulation analysis of detection probabilities and survey effort suggestthat greater temporal and spatial effort could make point-count surveys more applicable for evaluating goldeneagle occurrence in survey areas; however, increased effort would increase financial costs associated withadditional person-hours and logistics (e.g., fuel, lodging). Future surveys can benefit from a pilot study andcareful consideration of prior information about counts or densities of golden eagles in the survey area beforedeveloping a survey design. If information is lacking, survey planning may be best served by assuming lowdetection rates and increasing the temporal and spatial effort. Published 2017. This article is a U.S.Government work and is in the public domain in the USA.