Falconidae (Falcons)
American Kestrel,Falco sparverius. (Fig. 11.5) Male length 10 in (26 cm), female length 10 1/2 in (27 cm); male weight 3 3/8 oz (97 g), female weight 4 1/8 oz (116 g). Uncommon permanent resident in the White-Inyo Range at all elevations.
This species forages in open terrain where vegetation is sparse and low-growing, and where suitable perch sites are available; meadows, unforested slopes, sagebrush flats, and rocky outcrops are frequented. The American Kestrel is a generalized
Figure 11.5
American Kestrel
predator of invertebrates and small vertebrates. Grasshoppers, crickets, and other insects make up the bulk of their diet, but reptiles, mammals, and birds may also be taken. This small falcon typically searches for and attacks its prey from an exposed perch at a moderate height, striking on or near the ground surface. On windy days, however, the birds may hunt by hovering over the ground, especially where perches are sparse or lacking. American Kestrels also "hawk" insects on the wing or, uncommonly, forage directly on the ground for nonflying invertebrates. This species nests commonly in tree cavities, especially in old Northern Flicker holes, and rarely in earth banks or cliff crevices. Being highly maneuverable, American Kestrels harass larger birds of prey and Common Ravens by long stoops and swift ascents. Reference: Balgooyen (1976).
Prairie Falcon,Falco mexicanus. (Fig. 11.6) Male length 15 1/2 in (39 cm), female length 18 in (46 cm); male weight 1 1/8 lb (519 g), female weight 1 7/8 lb (849 g). Scarce resident in the White-Inyo Range at all elevations.
An arid-adapted species, the Prairie Falcon avoids heavily wooded areas. Open rocky canyons and ridgetops grown to Singleleaf Pinyon, sagebrush flats and slopes, alpine scrub, and grassland are preferred. There it searches for small mammals, birds, and invertebrates such as grasshoppers and crickets. Horned Larks are a common food item in open terrain. Prairie Falcons are swift and highly maneuverable in flight, and they deftly take prey from either the air or the ground. They also hunt while perched on a post or pole. Nests are built on rocky ledges or in cliff cavities, commonly far from water but near suitable foraging habitat. The Prairie Falcon can travel long distances daily away from the nest site in search of food. Reference: Cade (1982).
Figure 11.6
Prairie Falcon.