Unmanned aircraft systems enable three-dimensional viewshed-based assessment of potential disturbance to nesting raptors by recreational rock climbing

Unmanned aircraft systems (UAS) can be safer, less expensive, and less labor intensive than manned aircraft in wildlife conservation programs. Consequently, the use of UAS is increasing, but other than installation of line markers to reduce avian collision with power lines, UAS approaches generally involve passive observations. We wondered if UAS could more actively help guide conservation decision-making, so we used UAS-sourced photographs to create 3D models of cliffs to conduct viewshed-based assessments of potential disturbance to nesting raptors by recreational rock climbing. At Cathedral Spires Park and Clear Creek Canyon Park in Jefferson County, Colo., we collected 4790 photographs from which we constructed 3D models. We identified climbing routes and climbing areas with potential to disturb nesting Peregrine Falcons (Falco peregrinus) and Golden Eagles (Aquila chrysaetos). Our findings were useful in providing Jefferson County Open Space (JCOS) with quantitative data so that informed defensible resource management decisions could be made. This project provides an example of how UAS can be used to actively create products useful in wildlife conservation and management and, given the widespread and increasing popularity of rock climbing globally, likely can be generalized to other areas worldwide where rock climbers and nesting raptors share cliffs.