Raptor Breeding season report for Pinnacles National Monument - 2004

Emmons, Gavin

Annual Report The 2004 breeding season was the 18th year of raptor monitoring at Pinnacles National Monument. Field observations began 7 January 2004 and ended 30 June 2004. 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 2004 raptor-breeding season was successful, particularly for prairie falcons. Eighteen territories were occupied with eleven active-breeding prairie falcon territories confirmed. Thirtysix prairie falcons hatched, with thirty-three possibly fledging and thirty-one confirmed. Two territories failed (through predation) and were abandoned, one pair occupied a territory without nesting for the season, and one single falcon occupied a territory for the season. Of note, a peregrine falcon (Falco peregrinus) pair occupied the Hawkins territory throughout the 2004 breeding season. Although they did not nest this year, their presence marked the first time in 40 years that a peregrine falcon pair has occupied a territory through the breeding season at Pinnacles National Monument. Golden eagles were observed throughout the park. A new eagle nest was discovered at North Chalone Peak. Although the nest produced 1 hatchling, the nest failed (likely due to predation), and the site was abandoned. Additionally, five nests in three known territories in the park were not occupied this year. One known nest in a territory outside of the park produced one eaglet and a likely but unconfirmed fledgling. Additional raptor species active and nesting in the park included red-tailed hawks (Buteo jamaicensis), American kestrels (Falco sparverius), and Cooper’s hawks (Accipiter cooperii). Red-tailed hawk pairs occupied four territories, hatched eight young, and produced six confirmed fledglings, with eight total fledglings likely. American kestrels occupied eleven territories, with two fledglings confirmed in one territory, and a premature fledgling found in another territory. Cooper’s hawks were observed occupying three territories, with 1 fledgling observed near Chalone Creek along the East side road, near the Chalone housing turnoff. 2004 also marked the first year that captive-bred California condors (Gymnogyps californianus) were released at Pinnacles National Monument, with up to 6 condors active from Grassy Canyon to the High Peaks throughout the season. Condors were aggressively stooped by territorial raptors including peregrine and prairie falcons, and golden eagles, on numerous occasions, with one incident of an adult golden eagle hitting a condor and driving it from a feeding site. Condors were also observed displacing a juvenile golden eagle from the Grassy Canyon feeding site.

Raptor Breeding season report for Pinnacles National Monument - 2004

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