Prairie and Peregrine Falcon Occupancy and Productivity Monitoring at Pinnacles National Park: 2025 Annual Report

Emmons, Gavin

doi:10.36967/2317950

Pinnacles National Park (“Pinnacles”) provides diverse habitats for numerous cliff-nesting raptors, including prairie falcons (Falco mexicanus) and peregrine falcons (F. peregrinus), as well as a spectacular array of summits and cliff-wall routes for rock-climbers. This monitoring program was established to determine long-term trends in the number of occupied territories and productivity of nesting prairie and peregrine falcons. The monitoring program grew out of a need to reduce potential disturbance that climbers and off-trail hikers may have on cliff-nesting raptors. The falcon monitoring program began with a pilot effort in 1984, and after two years of no monitoring efforts in 1985 and 1986, monitoring data have been collected annually from 1987 to the present. This report summarizes the results from the 2025 breeding season and represents the 40th year of monitoring at the park, consistent with the standardized methods and procedures detailed in the Prairie Falcon Monitoring Protocol for Pinnacles National Monument (Emmons et al. 2011). To monitor falcons, field technicians surveyed all potential nest sites three times per breeding season, with visits spaced 21 to 28 days apart. We revisited those nests determined to be active to confirm rearing of nestlings and fledging of young. In 2025, we conducted monitoring from 1 January 2025 until 7 July 2025, with a total of over 150 possible and active nest sites monitored during 870 observation hours. For prairie and peregrine falcons combined, we documented 13 territorial pairs this year, with 12 pairs actively nesting. Seven nests successfully fledged 21 young; five nests failed. For prairie falcons specifically, we documented nine territorial pairs, with four nests successfully fledging 14 young. For peregrine falcons, we documented four territorial pairs, with three nests successfully fledging seven young. Falcon fecundity for the 2025 season was notably lower compared to the 39-year average. The data from 40 years of falcon monitoring at Pinnacles suggest an apparent cyclic population pattern in annual prairie falcon productivity, supplemented by increased peregrine falcon breeding efforts in recent years (Appendix C).

Prairie and Peregrine Falcon Occupancy and Productivity Monitoring at Pinnacles National Park: 2025 Annual Report

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