Foraging Ecology of Peregrine Falcons (Falco peregrinus) Along the Colorado River, Grand Canyon, Arizona

We compiled 355 observations of foraging events of peregrine falcons (Falco peregrinus) in Grand Canyon, downstream from Glen Canyon Dam on the Colorado River during 1973–1995, and documented abundance of prey, foraging behavior, and success in foraging. Peregrine falcons attempted to forage on ≥44...

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Bibliographic Details
Published in:The Southwestern naturalist 2009-09, Vol.54 (3), p.284-299
Main Authors: Stevens, Lawrence E, Brown, Bryan T, Rowell, Kirsten
Format: Article
Language:English
Subjects:
Animal ecology
Anseriformes
Behavior
Bird nesting
Birds
Birds of prey
Canyons
Ceryle alcyon
Dams
Ecology
Ecosystems
Falco peregrinus
Falcons
Feature s
Food and nutrition
Foraging
Foraging behavior
Freshwater
Hunting
Hymenoptera
National parks
Peregrine falcon
Podicipediformes
River ecology
Swallows
Swifts
Turbidity
Waterfowl
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Summary:We compiled 355 observations of foraging events of peregrine falcons (Falco peregrinus) in Grand Canyon, downstream from Glen Canyon Dam on the Colorado River during 1973–1995, and documented abundance of prey, foraging behavior, and success in foraging. Peregrine falcons attempted to forage on ≥44 species, including ≥40 species of birds: swifts and swallows (29%), waterfowl (Anseriformes, Podicipediformes, and similar birds, 27%), other waterbirds (waders and other large, non-anseriform waterbirds, 11%), bats (10%), large wasps (8%), and other species (15%). Frequency of foraging during the breeding season was positively related to overall abundance of prey, but relative intensity of predation (ratio of relative frequency of attack on a species to mean abundance of that species) increased on most species of prey in the usually turbid lower reach, where prey were less abundant. Air-to-air strikes were most common (94% of 271 cases for which data were available), followed by air-to-water strikes (4%), and air-to-ground strikes (2%). Tandem attacks occurred in ≥43% of cases. Overall foraging success was ≥52%, and was highest on large wasps (100%) and bats (87%), intermediate on large waterbirds (63%), swifts, swallows, and small terrestrial birds (42%), and waterfowl (40%), and lowest on belted kingfishers (Ceryle alcyon; 18%) and small shorebirds (
ISSN:0038-4909
1943-6262
DOI:10.1894/MH-19.1