Population Ecology of the Caribou (Rangifer Tarandus Granti) in Alaska PDF Download
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Author: Ronald O. Skoog
Publisher:
ISBN:
Category : Caribou populations
Languages : en
Pages :
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Book Description
Author: Ronald O. Skoog
Publisher:
ISBN:
Category : Caribou populations
Languages : en
Pages :
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Book Description
Author: Ronald O. Skoog
Publisher:
ISBN:
Category : Animal populations
Languages : en
Pages : 1450
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Book Description
The main purpose of this study was to obtain a comprehensive set of data on caribou ecology in Alaska particularly in regards to population dynamics and to proper management. It is based on twelve years of fieldwork conducted 1952-1964 with an emphasis on the Nelchina herd in Southcentral Alaska.
Author: Ronald Oliver Skoog
Publisher:
ISBN:
Category : Caribou
Languages : en
Pages : 0
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Author: David R. Klein
Publisher:
ISBN:
Category : Caribou
Languages : en
Pages : 66
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Book Description
Assesses research needs and priorities in relation to caribou management goals in Alaska.
Author: Karen H. Mager
Publisher:
ISBN:
Category : Caribou
Languages : en
Pages : 430
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Book Description
Alaskan caribou (Rangifer tarandus granti) are a valued game species and a key grazer in Alaska's terrestrial ecosystem. Caribou herds, defined by female fidelity to calving grounds, are management units. However, the extent to which herds constitute genetic populations is unknown. Historical fluctuations in herd size, range, and distribution suggest periods of contact and isolation between herds. Likewise, historical contact between caribou and introduced domestic reindeer (R.t. tarandus) created opportunities for hybridization, but its extent is not known. I conducted an interdisciplinary study to understand how historical processes influence genetic identity and population structure of caribou and reindeer. Interviews with herders and hunters in Barrow, Alaska, revealed that many reindeer migrated away with caribou in the 1940s despite herder efforts to prevent mixing. Local observations of reindeer-like animals in caribou herds today suggest feral reindeer may survive and interbreed. Using genetic analysis of North Slope caribou and Seward Peninsula reindeer (n = 312) at 19 microsatellite loci, I detected individuals with hybrid ancestry in all four caribou herds and in reindeer. Selective hunting of reindeer-like animals, along with herd size and natural selection, may remove reindeer from caribou herds over time. I used genetics as well to describe caribou population structure and determine how it is influenced by geography, historical demography, and ecotypes. I found that Alaskan caribou from 20 herds (n = 655) are subdivided into two genetic clusters: the Alaska Peninsula and the mainland. Alaska Peninsula herds are genetically distinct, while many mainland herds are not. I hypothesize that Alaska Peninsula herds have diverged due to post-glacial founder effects and recent bottlenecks driven by constraints to population size from marginal habitat and reduced gene flow across a habitat barrier at the nexus of the peninsula. I hypothesize that mainland herds have maintained genetic connectivity and large effective population size via range expansions and shifts over time. However, I find evidence that herds of different ecotypes (migratory, sedentary) can remain differentiated despite range overlap. Genetic evidence provides information for herd-based management, while also demonstrating the importance of spatial connectivity of herds and their habitats over the long-term.
Author: James W. Lieb
Publisher:
ISBN:
Category : Caribou
Languages : en
Pages : 54
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Book Description
Report on an evaluation of the Mentasta Caribou (Rangifer tarandus) Herd in southcentral Alaska. The population dynamics and status of the herd were determined through the gathering of information on productivity, cow and calf mortality, seasonal range use, and herd interchange from 1 Oct to 30 Sept. each year.
Author:
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Category :
Languages : en
Pages :
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Author: Mark Antone Ricca
Publisher:
ISBN: 9781303794544
Category :
Languages : en
Pages :
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Book Description
Introductions of mammalian herbivores to remote islands without predators allow a natural experiment to ask: 1) how herbivore populations persist and respond numerically and spatially when primarily under bottom-up control, and 2) how do the above-mentioned dynamics mediate feedbacks between plant and soil processes that could trigger a shift to a different state in ecosystems that have not ostensibly coevolved with herbivory? I took advantage of early- to- mid 20th century introductions of caribou and reindeer (Rangifer tarandus) to islands in the central Aleutian archipelago of Alaska to ask these questions.I used the Riney-Caughley 4-stage model (i.e., increase, K overshoot, decline, K re-equilibration) as a framework to test predictions of irruptive population growth and spatial expansion of caribou introduced to Adak Island. I utilized a time series of spatially explicit counts conducted intermittently over a 54-year period, whereby population size increased from 23 animals at the time of introduction to approximately 2900 animals by the year 2012. However, the pattern of numerical growth did not tightly fit the model predicted shape, and the population had not undergone all 4 stages. Population dynamics were characterized by two distinct periods of irruptive growth separated by a long stable period related to pulses in hunter-harvest rates. An unexpected pattern resembling logistic population growth occurred at the end of the time series that was most likely due to an additive combination of high levels of unreported hunter-harvest and intensifying density-dependent feedbacks on caribou fecundity and survival. Spatial use patterns during the post-calving season strongly supported model predictions, whereby high-density core areas expanded outwardly as population size increased. During the calving season, however, animals displayed marked site fidelity across the full range of population densities despite the availability of other suitable habitats for calving. Lastly, a small number of caribou emigrated to the adjacent island of Kagalaska at the end of the time series, which represents a new dispersal front in accordance with model predictions. I then asked if temporal and spatial variation in Rangifer herbivory accelerated ecosystem processes in maritime tundra to drive a feedback between increased graminoid production and rapid nitrogen cycling, or decelerated processes by stimulating shrub domination and slower N cycling. I measured plant and soil properties across three islands in the archipelago representing a chronosequence of elapsed time post-Rangifer introduction with distinct population dynamics within the Riney-Caughley framework nested within each island. The island chronosequence comprised: 1) Atka Island with ~100 years elapsed post-introduction, where Rangifer have experienced minimal harvest pressure that has likely contributed to the completion of all 4-irruptive stages, 2) Adak Island with ~ 50 years elapsed and kept at low density for ~ 35 years by harvest before undergoing rapid exponential growth characteristic of model stage-2, and 3) Kagalaska Island, which was set as a pseudo-control given the recent detection of very small numbers of caribou that emigrated from Adak. I also measured Rangifer spatial use within islands (indexed by pellet group counts) to determine how ecosystem processes responded to spatial variation in herbivory. Graminoids increased while dwarf-shrubs, lichens, and mosses decreased with herbivory history along the island chronosequence. Slow-growing Cladonia lichens that are highly preferred winter forage were decimated on both Rangifer-occupied islands. In contrast, increasing Rangifer spatial use within islands was correlated linearly with reductions in graminoid and forb biomass and non-linearly with reductions in dwarf-shrub biomass. However vegetation shifts associated with Rangifer along temporal and spatial gradients did not cascade strongly to affect belowground ecosystem function, whereby rates of net N-mineralization, NH4+ pools, and soil [delta]15N declined markedly along the chronosequence. Collectively, a multivariate ordination revealed strongly divergent ecosystem processes between Atka (characterized by lower fertility, fewer forbs and lichens) and Kagalaska (higher fertility, more abundant forbs, dwarf-shrubs, and lichens) that likely reflect a decrease in carrying capacity on Atka as predicted by the Riney-Caughley model. In contrast, ecosystem processes on Adak were intermediate between those on Atka and Kagalaska, which may indicate more transient alterations to plants and soil related to the relatively recent stage-2 irruption in Rangifer population size. These results support the hypothesis that Rangifer population persistence on islands is facilitated by successful exploitation of graminoid biomass as winter forage after palatable lichens are decimated, yet long-term grazing appears to reduce overall soil fertility. Finally, I asked how Rangifer modified or created heterogeneity in plant and soil processes at small-spatial scales on Adak via two discrete mechanisms. First, topographic variation stemming from small hilltop `knobs' that drain into semi-closed `swales' creates heterogeneity in forage resources that attract caribou. Use by caribou should then enhance or retard topographic-related heterogeneity in plant and soil processes depending on whether herbivory drives an acceleration or deceleration of ecosystem processes. Second, I asked if hunter-killed caribou-carcasses contributed to highly localized hotspots of soil and foliar nitrogen cycling, which was germane given the dramatic increase in recent harvest rates. Using a design of paired knob-swale plots in unreplicated drainages with high, low, or nominal caribou use, I found that high caribou use reduced heterogeneity in plant community structure but had little influence on variation in belowground processes associated with topography. Specifically, high use knobs had fewer and more compacted dwarf-shrub mats, reduced Cladonia lichen cover, and increased cover of deciduous shrubs and unpalatable lichens compared to all other plot types. However, these changes were not accompanied by higher biomass of graminoids and forbs that would be predicted if intense herbivory had an accelerating effect on ecosystem processes. High caribou use did not influence existing topography-related differences in inorganic soil-N pools or soil [delta]15N. Furthermore, caribou carcasses contributed to markedly elevated inorganic-N pools and higher foliar-N content despite driving greater net N-immobilization in comparison to control plots. Hence, large numbers of caribou carcasses scattered across the island landscape should add highly localized heterogeneity to N-cycling.
Author: Morten Meldgaard
Publisher: Museum Tusculanum Press
ISBN: 9788763511803
Category : Animals
Languages : en
Pages : 92
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Author: Morten Tryland
Publisher: CRC Press
ISBN: 0429952430
Category : Medical
Languages : en
Pages : 534
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Book Description
This book is a comprehensive presentation of health and diseases in reindeer and caribou, or just Rangifer, a key Circumarctic species with broad social and ecological value. It is an essential reference for anyone interested in the biology and health of wild or semi-domesticated reindeer and caribou, and is more broadly relevant for those with interests in other species of free-ranging and captive cervids. Beginning with a general introduction to Rangifer as a species, it then focuses on Rangifer "health" as a concept and describes the determinants of health at an individual and population level. Chapters cover a range of topics from nutrition and feeding to stress, non-infectious and infectious diseases, meat hygiene, capture and restraint, diagnosis and treatment of health issues, and finally, potential impacts of climate change on health of Rangifer. Reindeer and Caribou: Health and Disease compiles extensive research and experience-based information on issues ranging from drug doses for chemical immobilization, blood chemistry values, and raising an orphaned calf. In addition, it contains hundreds of high quality colour illustrations that contribute to its value as a diagnostic resource for recognizing various parasites, pathogens and signs of disease, both in live and dead animals. Each chapter is followed by a comprehensive list of references and a list of contact information for all the contributors, identifying world experts in the different areas of health for this circumpolar and fascinating species. This book is compulsory reading and an indispensable resource for anyone dealing with health in reindeer and caribou, including veterinarians, wildlife biologists and managers, reindeer herders/game ranchers, zoological husbandry personnel, and students with wildlife health.
