干旱区生态环境知识资源中心

We surveyed 7 species of predatory birds weekly during a 12-month period (December 1992 through November 1993) in the east Mojave Desert, California. The Common Raven (Corvus corax) was the most frequently observed species with an average of 6.9 sightings per 100 km. Turkey Vultures (Cathartes aura), Red-tailed Hawks (Buteo jamaicensis), Loggerhead Shrikes (Lanius ludovicianus), American Kestrels (Falco sparverius), Golden Eagles (Aquila chrysaetos), and Prairie Falcons (Falco mexicanus) were seen in decreasing order of frequency of observation through the study period. Ravens, Red-tailed Hawks, Loggerhead Shrikes, American Kestrels, and Prairie Falcons were seen throughout the year. Turkey Vultures were not present during winter months, while Golden Eagles were seen only during November and December. Turkey Vultures, Red-tailed Hawks, and ravens were most numerous on agricultural lands, while Loggerhead Shrikes were most common at urban areas. Raven numbers increased with increasing number of linear rights-of-way parallel to the survey route. Perching was the most common behavior type, although Turkey Vultures and ravens were often observed sealing, flying, or standing on the ground near highways. Transmission powerline towers and telephone poles were used as perch sites disproportionately to availability.