Natal and breeding dispersal of northern spotted owls

摘要: We studied the dispersal behavior of 1,475 northern spotted owls (Strix occidentalis caurina) during banding and radio-telemetry studies in Oregon Washington 1985-1996. The sample included 324 radio-marked juveniles 1,151 banded individuals (711 juveniles, 440 non-juveniles) that were recaptured or resighted after dispersing from initial location. Juveniles typically left nest last week May first two weeks June (x ± SE = 8 0.53 days, n 320, range 15 May-1 July), spent an average 103.7 days natal territory leaving (SE 0.986 137, 76-147 days). estimated mean date began to disperse was 19 September (95% CI 17-21 September) 30 25 September-4 October). Mean dates did not differ between males females among years. Siblings dispersed independently. Dispersal initiated with a series rapid movements away site few dispersal. Thereafter, most settled into temporary home ranges late October November remained there for several months. In February-April second pulse activity, many moving considerable distances before settling again their summer. Subsequent patterns highly variable, some permanently summer others occupying eventually on territories when they 2-5 years old. Final ranged 0.6-111.2 km 1.8-103.5 juveniles. distribution strongly skewed towards shorter distances, only 8.7% more than 50 km. Median 14.6 males, 13.5 24.5 females, 22.9 females. On average, within 4.2 7.0 widths sites, respectively. Maximum final largely independent number tracked. Although statistical tests direction based all indicated non-random, angular deviations 95% CI's associated samples large, r-values (vector length) small. This lead us conclude significant test results result large size biologically meaningful. Our enough whether individual random. owls, 22% 44% paired at 1 year age, but 1.5% 1.6% actually breeding age. At 2 68% 77% paired, 5.4% 2.6% breeding. contrast relocated age although recruitment territorial population occurred 1-5 old, 9% until > 5