Environmental Variation, Not Risk of Predation, Drives the Spatial Ecology of Sierra Nevada Bighorn Sheep PDF Download

Author: Jeffrey Todd Villepique
Publisher:
ISBN:
Category :
Languages : en
Pages : 123

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Author: Heather Elizabeth Johnson
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 229

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Book Description
An extinction vortex is one of the greatest threats to endangered species; when demographic, environmental, and genetic stochasticity interact with each other and with deterministic factors, such as habitat quality, to reinforce the demise of a small population. To successfully escape an extinction vortex and enable species recovery, all processes that affect endangered populations should be comprehensively assessed and incorporated into conservation plans. For my dissertation, I worked in conjunction with California Department of Fish and Game to develop a comprehensive research program to guide recovery efforts for federally endangered Sierra Nevada bighorn sheep, the rarest subspecies of mountain sheep in North America. I initiated a combination of demographic, habitat and genetic analyses to identify the stochastic and deterministic factors limiting the recovery of this subspecies, examine the relative and synergistic impacts of these factors on the performance of Sierra Nevada bighorn sheep, and the benefits of different management activities for stimulating recovery efforts. Just as the extinction vortex predicts, I found that small populations of Sierra Nevada bighorn sheep were driven by a number of stochastic and deterministic processes. Demographic, habitat, climate, predation, and genetic factors operated singly and in concert to shape the overall viability of this subspecies. The interaction of factors led to atypical demographic patterns that deviated from theoretical expectations and increased extinction risk. To alleviate extinction processes, I found that management strategies must be tailored to population-specific dynamics, targeting those vital rates and ecological drivers which have the greatest power to increase performance. Results from this study have elucidated critical aspects of Sierra Nevada bighorn sheep ecology, provided a recovery strategy for this subspecies, and supplied new quantitative tools for examining the dynamics of small and endangered populations. Ultimately, this work offers an example of assessing population viability, not in terms of probability of extinction, but in terms of quantifying conservation measures that will alleviate extinction dynamics and achieve endangered species recovery goals.

Author: Wildlife Services (U.S.)
Publisher:
ISBN:
Category : Bighorn sheep
Languages : en
Pages :

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Author: Erin Wood
Publisher:
ISBN:
Category : Bighorn sheep
Languages : en
Pages : 90

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The basic spatial ecology and habitat relationships of female bighorn sheep in Nebraska are poorly understood. Establishing seasonal patterns of space use and resource selection for this population at the margin of their historical and current range addresses a key knowledge gap and provides important baseline information for ongoing conservation efforts in Nebraska. We deployed GPS radio-collars on 56 adult ewes in western Nebraska to quantify seasonal space use, movements, and resource selection of ewes. To investigate spatial ecology, we quantified movements of ewes and the factors that influence home range size, seasonal use, and spatial stability across seasons. Home range behavior and seasonal movements within this population appear to differ from others that have strong migratory tendencies. Multivariate modeling highlighted seasonal differences in space use and predicted a generally positive, non-linear relationship between home range size and road density. We also quantified resource selection patterns of female bighorn sheep within their home ranges and inferred factors that influence resource selection with a focus on predation risk, forage efficiency, and human disturbance. We used mixed-effects logistic regression with used and available locations for each individual to evaluate selection of topographical features, escape terrain, an index of high quality forage, and natural and anthropogenic landscape features. Ewes selected escape terrain, more rugged terrain, higher elevations, and water in all seasons. Selection of roads, development, and crops varied by season and subpopulation. Our work elucidates behavioral patterns of female bighorn sheep in Nebraska that may influence their survival and reproductive success. Our results should contribute to improved understanding of the factors limiting population growth for this declining population of conservation concern.

Author: John David Wehausen
Publisher:
ISBN:
Category : Animal populations
Languages : en
Pages : 486

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Author: Harold Mooney
Publisher: Univ of California Press
ISBN: 0520278801
Category : Nature
Languages : en
Pages : 1008

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This long-anticipated reference and sourcebook for CaliforniaÕs remarkable ecological abundance provides an integrated assessment of each major ecosystem typeÑits distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of CaliforniaÕs ecological patterns and the history of the stateÕs various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the stateÕs ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of CaliforniaÕs environment and curious naturalists.

Author: Kenneth Wilson
Publisher: Cambridge University Press
ISBN: 1107136563
Category : Mathematics
Languages : en
Pages : 693

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Book Description
Introduces readers to key case studies that illustrate how theory and data can be integrated to understand wildlife disease ecology.

Author: Charles J. Krebs
Publisher: Benjamin-Cummings Publishing Company
ISBN: 9780321068798
Category : Science
Languages : en
Pages : 695

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Book Description
This best-selling majors ecology book continues to present ecology as a series of problems for readers to critically analyze. No other text presents analytical, quantitative, and statistical ecological information in an equally accessible style. Reflecting the way ecologists actually practice, the book emphasizes the role of experiments in testing ecological ideas and discusses many contemporary and controversial problems related to distribution and abundance. Throughout the book, Krebs thoroughly explains the application of mathematical concepts in ecology while reinforcing these concepts with research references, examples, and interesting end-of-chapter review questions. Thoroughly updated with new examples and references, the book now features a new full-color design and is accompanied by an art CD-ROM for instructors. The field package also includes The Ecology Action Guide, a guide that encourages readers to be environmentally responsible citizens, and a subscription to The Ecology Place (www.ecologyplace.com), a web site and CD-ROM that enables users to become virtual field ecologists by performing experiments such as estimating the number of mice on an imaginary island or restoring prairie land in Iowa. For college instructors and students.

Author: Nathalie Pettorelli
Publisher: Oxford University Press, USA
ISBN: 0199693161
Category : Nature
Languages : en
Pages : 205

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Book Description
This book provides a coherent review of NDVI including its origin, its availability, its associated advantages and disadvantages, and its possible applications in ecology, environmental monitoring, wildlife management, and conservation.

Author: Monica G. Turner
Publisher: Springer Science & Business Media
ISBN: 0387216944
Category : Technology & Engineering
Languages : en
Pages : 353

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Book Description
An ideal text for students taking a course in landscape ecology. The book has been written by very well-known practitioners and pioneers in the new field of ecological analysis. Landscape ecology has emerged during the past two decades as a new and exciting level of ecological study. Environmental problems such as global climate change, land use change, habitat fragmentation and loss of biodiversity have required ecologists to expand their traditional spatial and temporal scales and the widespread availability of remote imagery, geographic information systems, and desk top computing has permitted the development of spatially explicit analyses. In this new text book this new field of landscape ecology is given the first fully integrated treatment suitable for the student. Throughout, the theoretical developments, modeling approaches and results, and empirical data are merged together, so as not to introduce barriers to the synthesis of the various approaches that constitute an effective ecological synthesis. The book also emphasizes selected topic areas in which landscape ecology has made the most contributions to our understanding of ecological processes, as well as identifying areas where its contributions have been limited. Each chapter features questions for discussion as well as recommended reading.