Reproduction of ferruginous hawks exposed to controlled disturbance

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The Ferruginous Hawk (Buteo regalis) is a conspicuous grassland bird that is sensitive to human disturbance. In 1978 and 1979, we studied 62 nesting pairs and recorded their behavior and nesting success. At 24 of these nests, we daily created disturbances designed to simulate those associated with land development on western rangelands. The other nests were not disturbed. Treated nests and control nests differed significantly (P < 0.05) in the number that successfully fledged young. Thirty-three percent of the disturbed nests were deserted by the adults, although our presence in the vicinity of the nest was brief. Those disturbed nests that were successful fledged significantly fewer young (P < 0.05) than undisturbed nests. Based on our cumulative data, adults did not flush 60% of the time if our activities were more than 120 m from the nest and 90% of the time if they were more than 250 m from it. Accordingly, for intermittent and brief human disturbance during years when prey are abundant and Ferruginous Hawks are in good physiological condition, we suggest that a minimum buffer zone of 0.25 km around the nest is sufficient to prevent nest desertion by at least 90% of the population. Buffer zone should be expanded in years when prey are scarce, i.e., when the hawks appear to be less tolerant of disturbance.

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Reference Code: A85WHI01IDUS

Full Citation: White, C. M., and T. L. Thurow. 1985. Reproduction of ferruginous hawks exposed to controlled disturbance. Condor 87(1): 14-22.

Location: ANIMAL EF: BUTEO REGALIS