Download or read book Habitat Utilization by Spotted Owls in the West Central Cascades of Oregon written by Eric D. Forsman and published by . This book was released on 1980 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eight adult spotted owls (Strix occidentalis) on the west slope of the Cascade Range in Oregon were fitted with radio transmitters and observed for periods ranging from 271 to 383 days. Mean home range size for the owls was 1,177 ha (range = 920-1,376 ha). There was no significant difference between home range size of males and females. On the average, home ranges of individuals occupying adjacent territories overlapped by 12 percent (range = 3-25 percent). Home ranges of paired individuals overlapped by 50 to 73 percent. The size and shape of home ranges varied on a seasonal basis; generally, the largest home ranges were observed during winter. Nest sites were centrally located within the home ranges utilized by the owls. On the radiotelemetry study area, the mean nearest neighbor distance between nests of adjacent pairs was 2.88 km. On 11 other areas in western Oregon where suitable habitat was available, mean nearest neighbor distances ranged from 1.68 to 3.04 km. The overall mean nearest neighbor distance for the 12 areas was 2.42 km. Home ranges occupied by the radio tagged owls were so large that consistent defense of the entire home range was impossible. Territorial defense appeared to take the form of a decreasing zone of influence centered around the nest; areas near each nest were defended consistently, but defense became increasingly inconsistent with distance from the nest. Discrete territorial boundaries could not be determined and probably did not exist. Territorial interactions between individuals of the same sex were much more aggressive than interactions between individuals of opposite sex. Spotted owls may have responded less aggressively toward individuals of the opposite sex because the advantage of allowing potential mate replacements to remain within the territory outweighed other considerations. Except for a few instances in which 2 of the owls foraged in recently clear-cut areas or in rock talus, virtually all foraging occurred in forests over 30 years old. Old-growth forests, which covered 36 to 64 percent of the area on individual owl home ranges, were strongly preferred for foraging by all of the owls; 92 percent of all foraging occurred in such forests. Utilization of younger forests (30 to 200 years old) was generally either less than or not significantly different than expected, indicating that younger forests were less desirable for foraging than old-growth stands. Old-growth forests were also preferred for roosting (97 percent of all roosts). Large old trees apparently were preferred for roosting during inclement weather because they provided better overhead protection from rain and snow. Small trees in the understory were preferred during warm weather because they provided greater protection from high temperatures and solar radiation. Spotted owls were primarily nocturnal. On the average, they left their day roasts to begin foraging at 14 minutes after sunset and stopped foraging at 21 minutes before sunrise. Diurnal foraging was limited primarily to opportunistic attempts to capture animals that wandered into roost areas. The usual method of foraging was to move from perch to perch at night, watching and listening for potential prey. The average rate of movement while foraging in this manner was 247 m/hr, and the average distance moved per nightly foraging period was 2,782 meters (range = 320-8,895 m). Seven species of mammals comprised the nucleus of the diet, the northern flying squirrel (Glaucomys sabrinus), red tree vole (Phenacomys longicaudus), western red-backed vole (Clethrionomys occidentalis), deer mouse (Peromyscus maniculatus), western pocket gopher (Thomomys mazama), snowshoe hare (Lepus americanus), and bushy-tailed woodrat (Neotoma cinerea). The flying squirrel, the most common animal in the diet, comprised 42 percent of all prey captured. During mid-winter, 85 percent of the prey captured were arboreal mammals. During the rest of the year, terrestrial prey became more abundant in the diet, but the flying squirrel remained the most common animal in the diet. Mean prey size and dietary composition for male and female spotted owls were not significantly different; this suggested that males and females did not partition the prey resource on the basis of size or species. Estimates of biomass consumed per owl per day on the study area ranged from 77.6 to 164.8 g, but the latter estimate was probably inflated. Four hypotheses are presented to explain why spotted owls foraged primarily in older forests and avoided recently cutover areas: (1) the biomass of prey preferred by the owls may have been greater in older forests than in cutover areas, (2) switching from arboreal mammals in older forests to terrestrial mammals in cutover areas might have resulted in increased competition with other nocturnal predators, (3) prey may have been less accessible in the dense vegetation that developed on cutover areas, and (4) spotted owls may have been more susceptible to predation in cutover areas where escape cover was absent.

Download or read book Habitat Suitability Index Models written by Stephen A. Laymon and published by . This book was released on 1985 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The California Spotted Owl written by and published by . This book was released on 1992 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The California Spotted Owl written by Jared Verner and published by DIANE Publishing. This book was released on 1994 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covers: an assessment of the current status of the California spotted owl, its biology and habitat use, and forests where the subspecies occurs in the Sierra Nevada and southern California. Suggests the direction of future inventories and research, identifies projected trends in habitat, and offers guidelines and recommendations for management of the California spotted owl. Charts, tables, graphs and color photos.

Download or read book In a Dark Wood written by Alston Chase and published by Routledge. This book was released on 2017-07-12 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a Dark Wood presents a history of debates among ecologists over what constitutes good forestry, and a critique of the ecological reasoning behind contemporary strategies of preservation, including the Endangered Species Act. Chase argues that these strategies, in many instances adopted for political, rather than scientific reasons, fail to promote biological diversity and may actually harm more creatures than they help. At the same time, Chase offers examples of conservation strategies that work, but which are deemed politically incorrect and ignored. In a Dark Wood provides the most thoughtful and complete account yet written of radical environmentalism. And it challenges the fundamental—but largely unexamined—assumptions of preservationism, such as those concerning whether there is a "balance of nature," whether all branches of ecology are really science, and whether ecosystems exist. In his new introduction, Chase evaluates the response to his book and reports on recent developments in environmental science, policy, and politics. In a Dark Wood was judged by a recent national poll to be one of the one hundred best nonfiction books written in the English language during the twentieth century. A smashing good read, this book will be of interest to environmentalists, ecologists, philosophers, biologists, and bio-ethicists, and anyone concerned about ecological issues.

Download or read book Oregon Wilderness Act of 1983 written by United States. Congress. Senate. Committee on Energy and Natural Resources. Subcommittee on Public Lands and Reserved Water and published by . This book was released on 1984 with total page 1268 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In a Dark Wood written by and published by Transaction Publishers. This book was released on with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a Dark Wood presents a history of debates among ecologists over what constitutes good forestry, and a critique of the ecological reasoning behind contemporary strategies of preservation, including the Endangered Species Act. Chase argues that these strategies, in many instances adopted for political, rather than scientific reasons, fail to promote biological diversity and may actually harm more creatures than they help. At the same time, Chase offers examples of conservation strategies that work, but which are deemed politically incorrect and ignored. In a Dark Wood provides the most thoughtful and complete account yet written of radical environmentalism. And it challenges the fundamental—but largely unexamined—assumptions of preservationism, such as those concerning whether there is a "balance of nature," whether all branches of ecology are really science, and whether ecosystems exist. In his new introduction, Chase evaluates the response to his book and reports on recent developments in environmental science, policy, and politics. In a Dark Wood was judged by a recent national poll to be one of the one hundred best nonfiction books written in the English language during the twentieth century. A smashing good read, this book will be of interest to environmentalists, ecologists, philosophers, biologists, and bio-ethicists, and anyone concerned about ecological issues.

Download or read book Influence of Forest and Rangeland Management on Anadromous Fish Habitat in Western North America written by and published by . This book was released on 1979 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book General Technical Report PNW GTR written by and published by . This book was released on 1987 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pacific Yew CA ID OR WA written by and published by . This book was released on 1993 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pacific Yew written by and published by . This book was released on 1993 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pacific Yew Draft Environmental Impact Statement appendices written by and published by . This book was released on 1993 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: Item no. 0080-F.

Download or read book Draft Environmental Impact Statement written by and published by . This book was released on 1987 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings Symposium On Fire In Wilderness and Park Management U S Department Of Agriculture September 1995 written by and published by . This book was released on 1995 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecology and Management of Larix Forests written by and published by . This book was released on 1995 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book General Technical Report INT written by and published by . This book was released on 1995 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book General Technical Report PSW written by and published by . This book was released on 1978 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: