On 14 January 2015 near Tonopah, Nevada, roughly 3,000 of Crescent Dunes’ 10,347 mirrors were placed in a standby position that focused sunlight above its 640-foot tower. Over the next several hours, monitors recorded approximately 115 birds killed after flying through the concentrated halo.

On 14 January 2015 near Tonopah, Nevada, roughly 3,000 of Crescent Dunes’ 10,347 mirrors were placed in a standby position that focused sunlight above its 640-foot tower. Over the next several hours, monitors recorded approximately 115 birds killed after flying through the concentrated halo.

A 2015 standby test concentrated sunlight above Crescent Dunes. Reports put the bird toll at roughly 115 to 130; the incident prompted changes to mirror aiming and raised questions about mortality monitoring.