Accipitridae (Hawks and Eagles)
Cooper's Hawk,Accipiter cooperi. (Fig. 11.2) Male length 15 1/2 in (39 cm), female length 17 1/2 in (45 cm); male weight 10 1/3 oz (291 g), female weight 16 1/2 oz (466
Figure 11.1
Turkey Vulture.
Figure 11.2
Cooper's Hawk.
g). Scarce permanent resident in the White Mountains from the valleys to 9,500 ft (2,896 m).
This hawk prefers to nest in aspens, willows, and cottonwoods in canyon bottoms. Foraging takes them over adjacent slopes grown to pines, broken woodland, and brush. A skilled hunter, the Cooper's Hawk maneuvers through openings in foliage, around trees, and over clearings in search of small birds and mammals. Reptiles, amphibians, and large insects are taken infrequently. Like other accipiters, it actively pursues its prey while using vegetation to screen its approach. It may also dash toward prey from a concealed perch in dense foliage. Prey are commonly seized near the ground, in shrubs, or in the canopy of low cover. The hawk usually returns with its kill to feed within 100 ft (30 m) of the nest tree. References: Snyder and Wiley (1976), Reynolds and Meslow (1984).
Red-tailed Hawk,Buteo jamaicensis. (Fig. 11.3) Male length 20 1/2 in (52 cm), female length 23 in (58 cm); male weight 2 lb (910 g), female weight 2 2/3 lb (1,223 g). Common permanent resident in the White-Inyo Range, at all elevations up to 10,500 ft (3,200 m).
Figure 11.3
Red-tailed Hawk.
Red-tailed Hawks are one of the most widespread species in the region, occurring throughout a variety of habitats. They hunt for small and medium-sized mammals over broken woodland, brushy slopes, and grassland. Invertebrates, birds, reptiles, and amphibians are taken less commonly. Red-tailed Hawks search for terrestrial prey while soaring high above the ground or while perching quietly in a tree or on a pole. They attack with long dives or sudden plunges. The bulky stick nest is built on a cliff shelf or in a tree and, once abandoned, may serve importantly as a nesting site for large owls. During the breeding season, male Red-tailed Hawks swoop and ascend in exaggerated flight while carrying a snake or other conspicuous prey item in their talons. This courtship display may signify to the female that he is a competent hunter. References: Fitch, Swenson, and Tillotson (1946); Weathers (1983).
Golden Eagle,Aquila chrysaetos. (Fig. 11.4) Male length 32 in (81 cm), female length 34 in (87 cm); male weight 7 1/4 lb (3,293 g), female weight 8 7/8 lb (4,030 g). Uncommon resident in the White-Inyo Range, from the valley floors to the summits of the highest peaks.
Golden Eagles soar throughout these mountains over all available habitats, including brushland, Pinyon-juniper Woodland, Subalpine Forest, riparian cover in canyon bottoms, and alpine steppes. Open country is preferred for foraging. Mammals are taken primarily, but birds and some snakes may also be eaten. The composition
Figure 11.4
Golden Eagle.
of the diet depends on prey availability, but all animals ranging in size from mice to fawns and songbirds to grouse are fair game. This species is notorious for killing domestic livestock, especially lambs, but such events occur uncommonly. Golden Eagles hunt either from a perch or from the air while near the ground or soaring at great heights. The large stick nest is built on an inaccessible cliff ledge or in tall trees. Early in the breeding season, pairs of eagles conduct elaborate aerial courtship displays that involve mutual dives and other acrobatics. References: Brown and Amadon (1968), Olendorff (1975).