Recovery Plan for the Northern Spotted Owl - DRAFT

owned and contain little suitable habitat. Although owls are present in lownumbers on some of these lands, it is unclear whether the owls are selfsupportingor are a result of dispersing owls from nearby source populations.Predation and Competition. Great homed owls and northern spotted owlswere surveyed in the central portion of the province in 1989 and 1990, withgreat homed owls 60 percent as numerous as spotted owls (Johnson pers.comm., Table 2.5). Barred owls are distributed throughout the province andhave been recorded at 156 locations from 1980 through 1991.Goshawk densities are moderate within this province, and most goshawks areobserved within habitats also used by northern spotted owls. Goshawkpredation upon adult spotted owls has been observed (Desimone, pers. comm.).Province Isolation. Prior to development of the Portland metropolitan areaand the Willamette Valley, this province would have been connected to theOregon Coast Range at least along the Willamette River between Wilsonvilleand the Columbia River. Another possible forested connection may haveexisted in the vicinity of Salem.There is concern that the Columbia River Gorge, plus the effects of hydroelectricdams and other recent human activities along the river, have created abarrier to the movement of spotted owls between the Cascade provinces inWashington and Oregon. Spotted owl habitat in this area mainly occurs on theMt. Hood National Forest in Oregon and Gifford Pinchot National Forest inWashington.The connection to the Coast Range province is weak, and there is significantconcern for demographic instability and isolation of owls in the Coast Range.Habitat that would support east-to-west movements of owls between theseprovinces most likely can be achieved on BLM lands south of Eugene.Linkage to the Cascades province in California is threatened by past logging onBLM and private land, and by natural ecological conditions that limit forestdevelopment in the area.The western and eastern Cascades provinces adjoin along the crest of theCascades Mountains. A barrier to dispersal between these two provinces existsalong 40 percent of their common border and consists of high-elevation areasthat are 3 miles or more in width, with little or no forest cover.Vulnerability to Natural Disturbance. Habitat loss due to natural disturbancesin this province is caused primarily by fire and wind. Key areas of fireconcern for this province are along the Columbia River in the Mt. Hood NationalForest (Appendix F), and the area adjacent to the Klamath province insouthern Oregon. Although major wind events have occurred in this province(e.g., on Bull Run watershed in 1973 and 1983, Franklin and Forman 1987)most wind events occur on a smaller scale. The effects of most wind events willbe to accelerate windthrow along susceptible edges where clear-cuts and roadsborder protected forest stands. Within DCAs it is expected that, as theyounger forest stands develop, and through a program of aggressive firesuppression, the loss of habitat to wind and fire can be effectively reduced.Eastern Oregon CascadesThe eastern Oregon Cascades province is a narrow band of habitat extendingnorth-to-south along the east side of the Cascade crest from the ColumbiaRiver to the California border. Habitat suitable for owls is found in the mixedconifer zone existing between the high-elevation subalpine and mountain-54