Randall B. Boone

SERENGETI WILDEBEEST MIGRATORY PATTERNS MODELED FROM RAINFALL AND NEW VEGETATION GROWTH

We used evolutionary programming to model innate migratory pathways of wildebeest in the Serengeti Mara Ecosystem, Tanzania and Kenya. Wildebeest annually move from the southern short-grass plains of the Serengeti to the northern woodlands of the Mara. We used satellite images to create 12 average monthly and 180 10-day surfaces from 1998 to 2003 of percentage rainfall and new vegetation. The surfaces were combined in five additive and three multiplicative models, with the weightings on rainfall and new vegetation from 0% to 100%. Modeled wildebeest were first assigned random migration pathways. In simulated generations, animals best able to access rainfall and vegetation were retained, and they produced offspring with similar migratory pathways. Modeling proceeded until the best pathway was stable. In a learning phase, modeling continued with the ten-day images in the objective function. The additive model, influenced 25% by rainfall and 75% by vegetation growth, yielded the best agreement, with a multi-resolution comparison to observed densities yielding 76.8% of blocks in agreement (kappa = 0.32). Agreement was best for dry season and early wet season (kappa = 0.22-0.57), and poorest for the late wet season (0.04). The model suggests that new forage growth is a dominant correlate of wildebeest migration.

Spatial and temporal variability modify density dependence in populations of large herbivores

A central challenge in ecology is to understand the interplay of internal and external controls on the growth of populations. We examined the effects of temporal variation in weather and spatial variation in vegetation on the strength of density dependence in populations of large herbivores. We fit three subsets of the model ln(Nt) = a + (1 + b) x ln(N(t-1)) + c x ln(N(t-2)) to five time series of estimates (Nt) of abundance of ungulates in the Rocky Mountains, USA. The strength of density dependence was estimated by the magnitude of the coefficient b. We regressed the estimates of b on indices of temporal heterogeneity in weather and spatial heterogeneity in resources. The 95% posterior intervals of the slopes of these regressions showed that temporal heterogeneity strengthened density-dependent feedbacks to population growth, whereas spatial heterogeneity weakened them. This finding offers the first empirical evidence that density dependence responds in different ways to spatial heterogeneity and temporal heterogeneity.

Lines around fragments: effects of fencing on large herbivores

People construct fences to delineate land ownership and to control access to land. Fences accomplish several purposes, notable among these are containing livestock or wildlife raised for profit or subsistence, excluding use of vegetation within areas to be conserved and reducing conflicts between wildlife and humans. In addition, fences may offer unanticipated benefits such as vegetation within hedgerow fences providing cover to wildlife, or grazing by confined herbivores promoting native flora. However, because fences limit mobility of large herbivores, fenced areas become fragments within the landscape. Fences may entangle or electrocute herbivores, truncate migratory routes, excise important resources needed by large herbivores and allow resident herbivore populations to become too high and damage vegetation. More subtly, fencing parcels may reduce the carrying capacity of a landscape irrespective of habitat loss by eliminating access to heterogeneous forage patches. Normalised difference vegetation indices, derived from satellite images and reflecting green vegetation biomass, are used to suggest effects of fencing upon stocking rates. Ecosystem modeling quantified the decrease in herbivore stocking rate as a 300km 2 parcel was fragmented. When the parcel was fenced as 10km 2 sub-parcels, 19% fewer cattle could be supported, compared to the parcel being unfenced.

Evolution of models to support community and policy action with science: Balancing pastoral livelihoods and wildlife conservation in savannas of East Africa

We developed a “continual engagement” model to better integrate knowledge from policy makers, communities, and researchers with the goal of promoting more effective action to balance poverty alleviation and wildlife conservation in 4 pastoral ecosystems of East Africa. The model involved the creation of a core boundary-spanning team, including community facilitators, a policy facilitator, and transdisciplinary researchers, responsible for linking with a wide range of actors from local to global scales. Collaborative researcher−facilitator community teams integrated local and scientific knowledge to help communities and policy makers improve herd quality and health, expand biodiversity payment schemes, develop land-use plans, and fully engage together in pastoral and wildlife policy development. This model focused on the creation of hybrid scientific−local knowledge highly relevant to community and policy maker needs. The facilitation team learned to be more effective by focusing on noncontroversial livelihood issues before addressing more difficult wildlife issues, using strategic and periodic engagement with most partners instead of continual engagement, and reducing costs by providing new scientific information only when deemed essential. We conclude by examining the role of facilitation in redressing asymmetries in power in researcher−community−policy maker teams, the role of individual values and character in establishing trust, and how to sustain knowledge-action links when project funding ends.

Climate variability and impacts on east African livestock herders: the Maasai of Ngorongoro Conservation Area, Tanzania

East African pastoral adaptation and vulnerability to climate variability and climate change is assessed, using data from decisionmaking processes and ecological data of the Maasai of Ngorongoro Conservation Area as an example. The paper uses integrated modeling, linking PHEWS, a household model, to SAVANNA, an ecosystem model to look at the effects of drought and a series of wet years on the well-being of Maasai pastoralists. Model results suggest that the ecosystem is quite resilient and suggests that the Maasai of the NCA are not very vulnerable to climate variability. However the economic situation in the NCA is precarious and food insecurity is prevalent without drought. The result is that drought has a very negative effect on people.

Using diffusion models to simulate the effects of land use on grizzly bear dispersal in the Rocky Mountains

Timber harvests proposed for Trail Creek Watershed, in southwestern Montana, U.S.A., have been opposed because grizzly bear (Ursus arctos horribilis) dispersal from northern Montana wildernesses into the Greater Yellowstone Ecosystem may be less likely. We used an individual-based model to simulate grizzly bear responses to: 1) region-level management practices represented by ownership patterns, and 2) watershed-level changes in habitat availability due to proposed harvests and road building. We assigned permeabilities (i.e., values that represent how easily a bear can move through a patch) to ownership blocks (region-level) and habitat patches (watershed-level) based upon a literature review, and used a correlated random-walk diffusion model to simulate movements. Simulated bears were placed into rasterized landscapes in a stratified random manner. At the regional level, bears moved ≤1500 times (i.e., ≈ 1530 km), and their destinations were tallied. At the watershed level, the number of moves required for bears to leave the watershed were tallied. Sensitivity analyses were used to determine the variability of the results with respect to changes in some parameters of interest (i.e., permeabilities of private lands, harvest permeabilities, and disturbance indices).With the permeability of private land set at 50 (range: 0 to 99), simulated grizzlies did not disperse from the Scapegoat and Bob Marshall Wildernesses into Yellowstone National Park (0 of 10000 simulated individuals). Under the assumptions of this model, a linkage between the wildernesses in northern Montana and Yellowstone does not appear to exist. However, a significant number of simulated grizzlies (41%) dispersed from Anaconda Pintler Wilderness, which is near Trail Creek Watershed, into the wilderness ES in eastern Idaho. A linkage may exist between these sites.At the watershed-level, removal of forest habitat under proposed Harvest I (1.77% of the watershed cut) led to simulated grizzlies using slightly more moves (i.e., ≤ 5.6%, P=0.042) to exit the watershed than under existing conditions. Harvests of 3.5% of the watershed (planned Harvest II) did not alter the number of moves required to exit the watershed (P=0.068). When disturbances associated with roads and harvests were also examined, large increases in number of movements required to exit the watershed occurred (≤ 151%, P=0.002). These analyses suggest that grizzly bears would be disturbed while timber harvests were ongoing, but that long-term changes in movement would not occur if roads were closed following harvests. The analyses demonstrate the utility of applying individual-based diffusion models to landscape-level movements of animals, and identifies the need for telemetry studies to determine movement rates through specific habitats.

MODELING THE OCCURRENCE OF BIRD SPECIES: ARE THE ERRORS PREDICTABLE?

Typical assessments of models where many species occurrences are predicted (e.g., from species–habitat matrices or Gap Analyses) report overall omission and commission errors. Yet species’ attributes suggest that we may predict a priori that some species are more likely to be modeled correctly than others. Because the likelihood of modeling species correctly is related to species incidences in surveys, a method was created that ranked the 183 avian species known to be breeding in Maine as to how likely they would be to occur in surveys. Attributes (e.g., population level, niche width, aggregation) were used to model 79% of the variation in incidence within the Maine Breeding Bird Atlas. Likelihood of Occurrence Ranks (LOORs) were assigned to each species based upon the modeled incidences to reflect how likely the species are to be observed in future surveys. The occurrence of birds on areas with species checklists were then modeled and compared to the LOORs. For five of six areas, the number of species correctly modeled using species–habitat associations was highly correlated with LOORs: species judged a priori to be likely to be modeled correctly actually were. For one large area (9172 ha) with a checklist covering 52 years, the number of species correctly modeled was not correlated with LOORs, evidence that the checklist is essentially complete. In general, sites with checklists from many years (e.g., >10 yr) and from large areas (e.g., >1000 ha) yielded the lowest commission error. These results demonstrate that the confidence assigned to results where the occurrences of species are modeled (e.g., Gap Analysis) is highly dependent on the test sets and the species modeled.

An agro-pastoral household model for the rangelands of East Africa

Abstract East Africa contains areas with some of the greatest large mammal biodiversity on the planet. These areas are key natural resources for the economic development of the region. They are also key areas for pastoralists who have co-existed with wildlife for millennia. Increasing populations, conflicts between wildlife and cattle, and the growth of agriculture, are all placing great pressure on these lands This paper describes the development of a pastoralist socio-economic model that is linked to the Savanna ecosystem model. In this way, options and scenarios could be investigated for their impacts not only on the ecosystem but also on pastoralist households and their welfare. The model, named PHEWS (Pastoral Household and Economic Welfare Simulator), tracks the flow of cash and dietary energy in pastoralist households using a simple set of rules. The model was calibrated for the Ngorongoro Conservation Area (NCA), northern Tanzania. The results of two population increase scenarios are presented. Model results indicate that all households in NCA depend to some degree on outside sources of calories, and that pastoralist welfare in NCA, even with small amounts of agriculture allowed, is under severe pressure at current human population levels. Strengths and weakness of the model are discussed, and next steps in its application identified.

Density dependence in northern ungulates: interactions with predation and resources

Variation in the abundance of animals has traditionally been explained as the outcome of endogenous forcing from density dependence and exogenous forcing arising from variation in weather and predation. Emerging evidence suggests that the effects of density dependence interact with external influences on population dynamics. In particular, spatial heterogeneity in resources and the presence of capable predators may weaken feedbacks from density dependence to growth of populations. We used the Kalman filter to analyze 23 time series of estimates of abundance of northern ungulate populations arrayed along a latitudinal gradient (latitude range of 40°–70°N) to evaluate the influence of spatial heterogeneity in resources and predation on density dependence. We also used contingency tables to test whether density dependence was independent of the presence of carnivores (our estimate of predation) and multiple regressions to determine the effects of spatial heterogeneity in resources, predation, and latitude on the strength of density dependence. Our results showed that the strength of density dependence of ungulate populations was low in the presence of large carnivores, particularly at northern latitudes with low primary productivity. We found that heterogeneity in elevation, which we assume acted as a surrogate for spatial heterogeneity in plant phenology, also reduced effects of density dependence. Thus, we show that external forces created by heterogeneity in resources and predation interact with internal feedbacks from population density to shape dynamics of populations of northern ungulates.

Distance Education: An Exploration of Alternative Methods and Types of Instructional Media in Teacher Education

Universities currently are exploring an array of instructional media to facilitate the delivery of instruction. Consensus from the studies indicates that there is no significant difference in the achievement of students who participate in traditional or online coursework. However, little research has compared traditional learning with the new multimedia online technologies that are becoming more prevalent in distance education. This study investigated the achievement, student satisfaction, and instructor course evaluations of pre-service general education students who participated in three special education courses in which a variety of instructional media and methods were used. The media used were: (a) a traditional classroom, (b) an online classroom (WebCT), and a (c) class-in-a-box via multimedia CD-ROMs. The various methods used to deliver the instructional content included PowerPoint notes, lecture notes, digital videos, and the textbook. Results of the study revealed that there were no significant differences found between the achievement of the students and the three conditions (e.g., traditional classroom, the online classroom, or the class-in-a-box via multimedia CD-ROMs). Also, no significant differences were found in the student satisfaction of the three groups. All were satisfied with the type of media of instruction in which they participated. Finally, the instructor course evaluation results completed by the three groups were not significantly different, indicating that the three groups evaluated the instructor and the instructional media similarly. The implications of these results for delivering courses via distance education are discussed.