Factors affecting the size of ferruginous hawk home ranges

摘要: -We used radio-telemetry to track movements of seven adult male Ferruginous Hawks (Buteo regalis) in southcentral Washington. Home range size was estimated for each using minimum convex polygon, harmonic mean, adaptive kernel, and fixed kernel-based methods. Minimum polygon mean home ranges were significantly larger than those previously reported Hawks. varied substantially among males (mean = 90.3 km2, 17.7-136.4 kM2). There no relationship between brood size; however, there a significant (r2 0.964, P 0.018) the distance from nest site nearest irrigated agricultural field where some hunted. Kernel-based estimates showed two distinct core areas most males, one around second fields they Received 25 Aug. 1997, accepted 29 Oct. 1997. The Hawk is large grassland raptor that breeds shrubsteppe semi-arid regions western North America (Olendorff 1993). species thought be sensitive human-caused disturbance its nesting (Lokemoen Duebbert 1976, Bechard et al. 1990). Habitat degradation caused by agriculture overgrazing have been as threat species' survival (Howard 1975, Thurow 1980, Cottrell 1981, Gilmer Stewart 1983). In Oregon Washington, on periphery currently listed Threatened Washington which has an population 50 60 breeding pairs (Wash. Dept. Fish Wildl. 1996). This study undertaken provide information about spatial use patterns state Department Wildlife their recovery plan species. Herein, we report compare them with results literature. We estimate four different techniques: (MCP; Mohr 1947), (Dixon Chapman 1980), (Worton 1989, Kenward 1990) Lastly, relate variability individual factors such habitat type site, examine possible effects