Population Viability for Grizzly Bears (Ursus Arctos Horribilis) PDF Download
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Author: Mark S. Boyce
Publisher:
ISBN:
Category : Grizzly bear
Languages : en
Pages : 79
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Author: Mark S. Boyce
Publisher:
ISBN:
Category : Grizzly bear
Languages : en
Pages : 79
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Book Description
Author: Mark S. Boyce
Publisher:
ISBN: 9780944740101
Category : Grizzly bear
Languages : en
Pages : 39
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Book Description
Author: Richard D. Mace
Publisher:
ISBN:
Category : Bear populations
Languages : en
Pages : 108
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Book Description
Author: L. Scott Mills
Publisher:
ISBN:
Category : Grizzly bear
Languages : en
Pages : 11
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Book Description
Population viability analysis programs are being used increasingly in research and management applications, but there has not been a systematic study of the congruence of different program predictions based on a single data set. We performed such an analysis using four population viability analysis computer programs: GAPPS, INMAT, RAMAS/AGE, and VORTEX. The standardized demographic rates used in all programs were generalized from hypothetical increasing and decreasing grizzly bear (Ursus arctos horribilis) populations. Idiosyncracies of input format for each program led to minor differences in intrinsic growth rates that translated into striking differences in estimates of extinction rates and expected population size. In contrast, the addition of demographic stochasticity, environmental stochasticity, and inbreeding costs caused only a small divergence in viability predictions. But, the addition of density dependence caused large deviations between the programs despite our best attempts to use the same density-dependent functions. Population viability programs differ in how density dependence is incorporated, and the necessary functions are difficult to parameterize accurately. Thus, we recommend that unless data clearly suggest a particular density-dependent model, predictions based on population viability analysis should include at least one scenario without density dependence. Further, we describe output metrics that may differ between programs; development of future software could benefit from standardized input and output formats across different programs.
Author: Erin Sherry
Publisher:
ISBN:
Category : DNA fingerprinting of animals
Languages : en
Pages : 310
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Book Description
?Grizzly bears (Ursus arctos horribilis) are one of the largest terrestrial North American mammals. Once the most widespread bear species in the world, the grizzlies’ range and numbers have been reduced by fifty percent since 1890. These bears occur at low densities, are reproductively conservative, have large home ranges, and require a diversity of complex wilderness habitats where human activity is minimal. In the Banff National Park / Kananaskis Country region of southwestern Alberta, the grizzly bear has survived, albeit in reduced numbers and with continual loss of habitat. Current estimated grizzly bear numbers deviated significantly from current estimated population potential reflecting such human impacts as over-harvesting, illegal mortalities, habitat alienation, and habitat fragmentation. There is a pressing need for population inventory research. Managers lack baseline population information. Existing estimates of population parameters are unreliable, involving broad confidence limits and problems related to methods, sample sizes, and mark-recapture model biases. This study reviews methodologies for assessing grizzly bear populations and the difficulties encountered in these studies. Researchers interested in monitoring the status and trends of grizzly populations have used a variety of methods - secondhand reports, harvest data indices, bait and scent stations indices, surveys of bear sign, population modelling, direct counts, aerial surveys, and mark-recapture population studies. Each suffers from problems of assumptions, sample size, and uncontrolled variability. As Harris (1986) admits, none can be accepted unequivocally, but all approaches have some potential utility. This dissertation explores the development and application of DNA-based mark-recapture methods to evaluate a grizzly bear population in the eastern slopes of the Canadian Rocky Mountains. Forty scent station ‘hair traps’ were monitored for a total of 1328 site nights and produced 250 hair samples: 165 brown or grizzled hair samples; 74 glossy, jet black hair samples; and 11 non-bear hair samples. Of these 250 hair samples collected, 223 had intact follicles and produced DNA samples. DNA-based mark-recapture can be exploited at several levels of population monitoring resolution depending upon population investigation objectives, financial constraints, and logistical considerations. This technique can be used to provide a basic population inventory, to assess absolute abundance, to evaluate demographic processes, or to provide information on the genetic composition or biotoxin accumulation levels of a bear population. In mountainous, remote, forested regions, such as the Central Rockies ecosystem, DNA-based mark-recapture methods present a viable alternative to physical mark-recapture techniques and are superior to photographic-based mark-recapture methods. More research is required to conclusively show that DNA-based mark-recapture will provide objective and replicable estimates of grizzly bear population parameters banded by acceptable confidence limits. The problems of small sample sizes, and of mark-recapture model assumption violations due to unequal capture probabilities and lack of closure, remain intractable in this study.?--Leaf viii.
Author:
Publisher:
ISBN:
Category : Brown bear
Languages : en
Pages : 28
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Author: Barbara A. Somervill
Publisher: Cherry Lake
ISBN: 1602795568
Category : Juvenile Nonfiction
Languages : en
Pages : 36
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Book Description
The grizzly bear once roamed much of western North America. In the early 1800s, as many as 50,000 grizzly bears lived in the West. As settlers pushed westward, the bears lost much of their habitat. Fewer than 1,000 grizzlies remained in the lower 48 U.S. states when the bear was listed as endangered. Read this book to learn how grizzly bears came close to extinction and find out what is being done to increase their numbers and insure their survival
Author: Don L. Brown
Publisher:
ISBN:
Category : Endangered species
Languages : en
Pages : 214
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Author: John E. Becker
Publisher: Kidhaven
ISBN: 9780737715347
Category : Juvenile Nonfiction
Languages : en
Pages : 56
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Book Description
Gigantic bear -- Disappearance -- Grizzly bear recovery -- Unclear future for grizzlies.
Author: United States. Congress. Senate. Committee on Appropriations. Subcommittee on the Department of the Interior and Related Agencies
Publisher:
ISBN:
Category : Grizzly bear
Languages : en
Pages : 246
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Book Description
