Raptor breeding season report for Pinnacles National Monument - 2007.

Emmons, Gavin

Pinnacles National Monument (PINN) provides a diverse habitat for numerous cliff-nesting raptors, including prairie falcons (Falco mexicanus), peregrine falcons (F. peregrinus) and golden eagles (Aquila chrysaetos), as well as a spectacular array of summits and cliff-wall routes for rock-climbers. This monitoring effort was established to determine long-term population trends of nesting prairie falcons and other raptors. The effort grew out of a need to reduce potential disturbance that climbers and off-trail hikers may have on cliff-nesting raptors. This report summarizes the results from the 2007 breeding season and represents the 21st year of monitoring at the monument. Field observations began 7 January 2007 and ended 25 July 2007. The 2007 raptor-breeding season was successful for prairie falcons. Fourteen territorial falcon pairs were documented this year with 12 pairs actively nesting. Thirty-five prairie falcons hatched, with 33 possible fledglings confirmed. Three nests failed (two likely due to predation or environmental exposure and one to eggs failing to hatch), one pair occupied a territory without nesting for the season, and one pair abandoned a territory after occupying the area through the first half of the season. A peregrine falcon pair successfully nested and fledged three young in the Hawkins territory, marking the third consecutive year that a successful peregrine falcon nesting effort has been documented at PINN in the last 49 years. Golden eagles were observed throughout the monument. Five nests in three known territories in the monument were not occupied this year. One known nest on the west side of North Chalone Peak produced one nestling, and a documented nest in the Eucalyptus Grove territory outside of the monument produced two eaglets. Fledging from the Eucalyptus Grove nest was confirmed for one young but likely for both. Fledging at the North Chalone nest was likely but unconfirmed. The 2007 breeding season was also successful for additional raptor species nesting in the monument, with 45 nests representing 12 raptor species. This is the second highest number of nests and species documented in a single season after the record numbers in the 2006 season. Nests for California species of concern were recorded this season for long-eared owls (Asio otus), Cooper’s hawks (Accipiter cooperii), sharp-shinned hawks (A. striatus), and white-tailed kites (Elanus leucurus). However, nesting pairs, successful nests, and fecundity rates for these species were all lower than numbers documented in 2006. One active nest for turkey vultures (Cathartes aura) was documented in 2007, and represented the third confirmed in the monument in 23 years. One long-eared owl nest produced three hatchlings, with with two fledglings confirmed and a third likely. One white-tailed kite nest failed to produce hatchlings or fledglings, likely due to predation or abandonment. Other nesting raptor species documented in the monument included red-tailed hawks (Buteo jamaicensis), red-shouldered hawks (B. lineatus), American kestrels (Falco sparverius), and great-horned owls (Bubo virginianus). 2007 also marked the fourth year that captive-bred California condors (Gymnogyps californianus) were active and free-flying at PINN, with up to 19 condors active from Grassy Canyon to the High Peaks, and moving between PINN and Big Sur on the coast throughout the season. 2007 also marked the first deaths of PINN condors, with #307 and #417 dying due to causes not related to lead poisoning. Condors were aggressively stooped by territorial raptors including peregrine and prairie falcons on numerous occasions. Condors were also observed displacing golden eagles, turkey vultures, and corvids from the Grassy Canyon condor feeding sites.

Raptor breeding season report for Pinnacles National Monument - 2007.

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