Raptor Breeding season report for Pinnacles National Monument - 2005

Emmons, Gavin

The 2005 breeding season was the 19th year of raptor monitoring at Pinnacles National Monument. Field observations began 12 January 2005 and ended 21 July 2005. Pinnacles National Monument provides a diverse habitat for numerous cliff-nesting raptors, including sensitive species such as prairie falcons (Falco mexicanus) and golden eagles (Aquila chrysaetos), as well as a spectacular array of summits and cliff-wall routes for rock-climbers. Therefore, the behavioral and physical effect that climbers and off-trail hikers have on cliffnesting raptors is studied. The 2005 raptor-breeding season was successful for prairie falcons. Twenty territories were occupied with ten active-breeding prairie falcon territories confirmed. Thirty-one prairie falcons hatched, with twenty-seven possibly fledging and confirmed. One nest failed, likely due to abandonment, and three pairs occupied territories without nesting for the season. Of particular note, a peregrine falcon (Falco peregrinus) pair successfully nested and fledged three young in the Hawkins territory, marking the first successful peregrine falcon nesting effort at Pinnacles National Monument in 48 years. Golden eagles were observed throughout the park. Six nests in four known territories in the park were not occupied this year. One known nest in the Eucalyptus Grove territory outside of the park produced two eaglets. Fledging was confirmed for one of the eagle young but likely for both. The 2005 breeding season was particularly successful for additional raptor species nesting in the park, including red-tailed hawks (Buteo jamaicensis), American kestrels (Falco sparverius), Cooper’s hawks (Accipiter cooperii), sharp-shinned hawks (Accipiter striatus), barn owls (Tyto alba), and long-eared owls (Asio otus). Red-tailed hawk pairs occupied six territories, hatched eleven young, and produced nine confirmed fledglings, with ten total fledglings likely. American kestrels occupied ten territories, with eight fledglings confirmed in five territories. Cooper’s hawks were confirmed nesting in the park along the Bench Trail; a territorial pair produced five nestlings that failed due to predation. Sharp-shinned hawks were confirmed nesting near the Moses Spring trailhead and in the South Wilderness, with eight fledglings confirmed from the two territories. A barn owl pair produced four nestlings in D. Soto Canyon, with fledging unconfirmed, and three long-eared owl fledglings were documented in Grassy Canyon. 2005 also marked the second year that captive-bred California condors (Gymnogyps californianus) were released at Pinnacles National Monument, with up to 7 condors active from Grassy Canyon to the High Peaks throughout the season. Condors were aggressively stooped by territorial raptors including peregrine and prairie falcons, on numerous occasions, with one incident of an adult bald eagle repeatedly stooping a condor. Condors were also observed displacing turkey vultures and corvids from the Grassy Canyon feeding site.

Raptor Breeding season report for Pinnacles National Monument - 2005

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