Prairie and Peregrine Falcon Occupancy and Productivity Monitoring at Pinnacles National Park: 2024 Annual Report

Emmons, Gavin

doi:10.36967/2314923

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 2024 breeding season and represents the 39th 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 2024, we conducted monitoring from 1 January 2024 until 17 July 2024, with a total of over 150 possible and active nest sites monitored during 850 observation hours. For prairie and peregrine falcons combined, we documented 12 territorial pairs this year, with 10 pairs actively nesting. Six nests successfully fledged 20 young; four nests failed. For prairie falcons specifically, we documented eight territorial pairs, with four nests successfully fledging 17 young. For peregrine falcons, we documented four territorial pairs, with two nests successfully fledging three young. Falcon fecundity for the 2024 season was notably lower compared to the 38-year average. The data from 39 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: 2024 Annual Report

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