American Bison - Buffalo Field Campaign

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Appropriate facilities usually include custom sized and constructed chutes and alleyways, crash gates, and chute crowding tubes. It is expensive to construct facilities safe for bison (and the people working with them), and we strongly recommend visiting facilities that have proven to be safe and effective. Highly credible facilities include those at YNP (Gardiner, Montana), the Baca Ranch (Colorado), Badlands National Park (South Dakota), and EINP (Alberta). 9.7 Modelling to Assess Bison Populations and Habitat Computer models are routinely used to improve our understanding of bison population and disease dynamics, and to forecast probable genetic consequences resulting from particular management actions. In the future, we should expect even more widespread use of quantitative models, which can, and likely will, be used for a broad range of purposes. A detailed treatise on modelling is well beyond the scope of this plan. The main goals of this section are, therefore, to provide readers with the minimal background necessary to seriously consider the utility of using an existing model, or of constructing a new management-oriented model, and to provide sufficient insight to the modelling process, that they can reasonably evaluate the validity and usefulness of model results, or at least ask questions that will help resolve these issues. For conservation purposes, population viability analysis (PVA) and population habitat viability assessment (PHVA) have become common, and important, approaches for assessing existing populations and for evaluating potential restoration or reintroduction projects. We restrict PVA and PHVA to analyses that employ quantitative modelling to assess the risk of extinction, or which attain a quantitative population threshold greater than extinction (“quasi-extinction”, from Ginzburg et al. 1982; Burgman et al. 1992; Ralls et al. 2002). Other thresholds for evaluation could include attaining a specified level of inbreeding depression or allelic diversity, or estimating the likelihood that a proposed introduction plan will result in establishment. Conclusions drawn from expert panels, committees, and other source of opinions, in the absence of a quantitative model, do not constitute a PVA (Reed et al. 2002). PHVA is a much broader process than PVA, and includes evaluation of geographical, social, regulatory, and ecological considerations that may significantly affect a species. The PHVA process includes a broad range of stakeholders and leads to specific recommendations for conserving a species in the area considered (http://www.cbsg.org/cbsg/phva/index.asp). Viability analysis is important to bison conservation because so many bison populations are small and clearly at risk, and because we have a rich knowledge of factors necessary to conduct credible and insightful evaluations. 100 American Bison: Status Survey and Conservation Guidelines 2010 The small size of many bison herds has raised concerns about retention of genetic diversity, and these concerns motivated detailed simulations to evaluate effects of management actions on retention of genetic variation in bison herds (Gross et al. 2006; Halbert et al. 2005; Wilson and Zittlau 2004). Other modelling studies have focused on brucellosis dynamics and its control in bison (Dobson and Meagher 1996; Gross et al. 1998; 2002; Peterson et al. 1991; Treanor et al. 2007) and on illustrating population dynamics of bison (Brodie 2008). All wildlife models are ultimately limited by data availability, and model results can be misleading when forecasts are presented with an apparent precision that is not justified by the underlying model assumptions, structure, or the accuracy of model parameters (Ralls et al. 2002; Reed et al. 2002). In general, the most appropriate use of simulation model results is to evaluate the merits of alternative management actions, rather than to define an absolute threshold population size. In particular, minimum critical population sizes may be sensitive to small errors in parameter estimates, or to the functional structure of strong environmental perturbations. 9.7.1 Guidelines for using computer simulations The first critical step is to clearly define the objectives of the modelling exercise. If the intent is to evaluate management actions, the best objectives are quantitative, specific, time- bound, and consist of “treatment” variables (e.g., number of founders, number or proportion removed) that can reasonably be simulated by a computer model. A good objective must include the likelihood of achieving the desired results, the quantitative value of a threshold, and a time horizon. For example, a bison PVA used the genetic objective to achieve a 90% probability of retaining 90% of currently observed selectively neutral genetic heterozygosity for 200 years (Gross et al. 2006). Below, we list steps that will be required to construct a computer model to support bison conservation. A number of recent treatises provide more detailed information about this process (we especially recommend Burgman et al. 1993; Bessinger and Westphal 1998; Bessinger and McCullough 2002; Hilborn and Mangel 1997). Although we list steps sequentially, most modelling exercises are iterative and involve simultaneously working through a number of these tasks and revisiting them as more information or insight becomes available. 1. Clearly articulate the objectives of the modelling exercise. It is essential to clearly identify a small, discrete set of “treatments” and “responses”. What management must be evaluated? What is the relevant time frame? What model outputs are to be evaluated?
2. Determine the required scope of model. Single or multiple species? Age or stage structured? One or more population units? Spatially homogeneous or with spatial structure? What is the geographical extent? Are animal-habitat feedbacks necessary? 3. Evaluate existing software and decide whether to use an existing programme or to construct a new model. Considerable time and money can be saved by using “off the shelf” software, such as RAMAS (http://www.ramas.com/software.htm), Vortex (Lacy 1993), ALEX (Possingham et al. 1992), or another modelling environment. 4. Collect necessary data and estimate model parameters. This can be a huge step. Data will be needed to estimate mean vital rates and realistic estimates of variance. Ecosystem or habitat models will require much additional information to determine carrying capacity and animal-ecosystem feedbacks. Most population-habitat models used for PVA will include catastrophes, estimates of variance in habitat carrying capacity, and specific assumptions on the form and process of density dependence. 5. Construct, calibrate, and run the model. Evaluate model results. Considerable effort may be required to understand and comprehensively evaluate model inputs, and to understand model results. Output from a simulation exercise usually includes huge quantities of data that will need to be reduced, summarised, and presented in an understandable form. 6. Package results in a digestible and understandable format. This is a vastly underappreciated problem, and it will be much easier if the model objectives were clear and concisely stated at the outset. 7. Ralls et al. (Table 25.4 in Ralls et al. 2002) provide a specific checklist for evaluating the quality of a PVA, and this checklist applies equally well to many additional conservation modelling exercises. They provide “yes-no” questions that focus on model objectives, model structure, data and parameter estimation, analysis of model outcomes, handling of model uncertainty, interpretation, and peer review. These criteria provide a sound framework for helping to ensure models are constructed and used in an appropriate fashion. 9.8 Conclusions While many topics are addressed in this chapter, effective management of bison ultimately relies on the judicious application of common sense and good judgement. When bison have access to sufficient space and forage, and are left relatively undisturbed, they are more than fully capable of taking care of themselves. Nonetheless, most bison will not experience natural conditions that include wide-open spaces and intact predator communities, so we hope the guidelines provided will support science-based management programmes that lead to more effective conservation and restoration of bison. These guidelines focus on widespread common management issues— population management, disease, and genetic management. These guidelines and principles will ensure that key issues are addressed, and citations will help managers find more detailed information that may be necessary to accommodate specific situations. American Bison: Status Survey and Conservation Guidelines 2010 101
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American Bison Status Survey and Co
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American Bison Status Survey and Co
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Table of Contents Acknowledgements
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6.3 Demographics ..................
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9.6 Active Management: Handling, He
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This manuscript is the product of m
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ABS American Bison Society ABSG Ame
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The publication of this IUCN Americ
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and foothills. Bison have a profoun
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Chapter 1 Introduction: The Context
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composition and function, as well a
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Chapter 2 History of Bison in North
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Figure 2.1 Original ranges of plain
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Charles Alloway (Manitoba), Charles
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nomadic “Plains Indian Culture”
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Chapter 3 Taxonomy and Nomenclature
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demonstrate that Bison and Bos were
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from their original habitat near th
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Chapter 4 Genetics As a science, po
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Selection for diversity in one syst
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cross, however, the latter is more
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the conservation of the wild specie
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Chapter 5 Reportable or Notifiable
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one) followed by its widespread dis
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cattle at similar levels to S19 (Ch
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long as 156 days post-infection. So
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and elk herds migrate across severa
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These concepts are being developed
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Chapter 6 General Biology, Ecology
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leave the herd prior to calving or
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historically dependent on a combina
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6.2.1.2.1 Northern mixed grasslands
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woodland caribou (Rangifer tarandus
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Page 69 and 70: Table 6.4 Age-specific reproductive
Page 71 and 72: 6.3.4 Population growth rates The r
Page 73 and 74: Chapter 7 Numerical and Geographic
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Page 77 and 78: Figure 7.4 Representation of plains
Page 79 and 80: Plate 7.3 Male plains bison sparrin
Page 81 and 82: Chapter 8 Legal Status, Policy Issu
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Page 85 and 86: Table 8.1 Current legal status of p
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Page 103 and 104: Chapter 9 Conservation Guidelines f
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Page 111 and 112: Table 9.4 Important considerations
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Page 123 and 124: • Creating education, awareness a
Page 125 and 126: 10.3 The “Ecosystem Approach” f
Page 127 and 128: anywhere without engaging stakehold
Page 129 and 130: Interventions (e.g., supplemental f
Page 131 and 132: Agabriel, J. and Petit, M. 1996. Qu
Page 133 and 134: Byerly, R.M., Cooper, J.R., Meltzer
Page 135 and 136: Dragon D.C. and Rennie, R.P. 1995.
Page 137 and 138: Gilpin, M.E. and Soulé, M.E. 1986.
Page 139 and 140: Joern, A. 2005. Disturbance by fire
Page 141 and 142: Matthews, S.B. 1991. An assessment
Page 143 and 144: Possingham, H.P., Davies, I., Noble
Page 145 and 146: Shaw, J.H. 1995. How many bison ori
Page 147 and 148: van Zyll de Jong, C.G. 1986. A Syst
Page 149 and 150: Appendix A North American conservat
Page 151 and 152: Plains bison (continued) State/Prov
Page 154: INTERNATIONAL UNION FOR CONSERVATIO
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