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Our understanding of fire and grazing is largely based on small-scale experimental studies in which treatments are uniformly applied to experimental units that are considered homogenous. Any discussion of an interaction between fire and grazing is usually based on a statistical approach that ignores the spatial and temporal interactions on complex landscapes. We propose a new focus on the ecological interaction of fire and grazing in which each disturbance is spatially and temporally dependent on the other and results in a landscape where disturbance is best described as a shifting mosaic (a landscape with patches that vary with time since disturbance) that is critical to ecological structure and function of many ecosystems. We call this spatiotemporal interaction pyric herbivory (literal interpretation means grazing driven by fire). Pyric herbivory is the spatial and temporal interaction of fire and grazing, where positive and negative feedbacks promote a shifting pattern of disturbance across the landscape. We present data we collected from the Tallgrass Prairie Preserve in the southern Great Plains of North America that demonstrates that the interaction between free-roaming bison (Bison bison) and random fires promotes heterogeneity and provides the foundation for biological diversity and ecosystem function of North American and African grasslands. This study is different from other studies of fire and grazing because the fires we examined were random and grazing animals were free to roam and select from burned and unburned patches. For ecosystems across the globe with a long history of fire and grazing, pyric herbivory with any grazing herbivore is likely more effective at restoring evolutionary disturbance patterns than a focus on restoring any large vertebrate while ignoring the interaction with fire and other disturbances.

Prior to European colonization and the introduction of cattle, bison were the prominent grazing ungulates throughout North American grasslands. Yet, relative zoogeomorphic impacts between bison and cattle on grassland streams remain largely unknown. Utilizing a paired watershed study design, we compared baseflow suspended sediment concentrations across ten watersheds and four grazing treatments (ungrazed, bison-grazed, moderately stocked cattle-grazed, and intensively stocked cattle-grazed) in the Flint Hills subregion of the Great Plains. Additionally, we determined whether periods of increased thermal stress led to higher sediment concentrations within each treatment. Water samples were analyzed for total suspended solids (TSS, mg/L), nonvolatile suspended solids (NVSS, mg/L), and percentage organic matter (POM, percent). Intensively stocked cattle-grazed treatments produced significantly higher TSS and NVSS concentrations relative to ungrazed (TSS p = 0.012, NVSS p < 0.01) and bison-grazed treatments (TSS p = 0.082, NVSS p < 0.01). Moderately stocked cattle-grazed treatments contained significantly higher NVSS concentrations relative to bison-grazed treatments (p = 0.057). Bison-grazed and ungrazed treatments contained similar sediment concentrations (TSS and NVSS p > 0.10). Additionally, intensively and moderately stocked cattle-grazed treatments showed a significant increase in sediment concentrations with increasing temperature (p = 0.024 and p = 0.08, respectively), whereas bison-grazed and ungrazed treatments did not (p > 0.10). At the subdaily timescale, the highest sediment concentrations within cattle-grazed treatments and the greatest difference in sediment concentrations between cattle-grazed and ungrazed treatments coincided with the hottest daily temperatures, further highlighting that cattle-grazing impacts are influenced by thermal conditions.

Species diversity has declined in ecosystems worldwide as a result of habitat fragmentation, eutrophication, and land-use change. If such decline is to be halted ecological mechanisms that restore or maintain biodiversity are needed. Two long-term field experiments were performed in native grassland to assess the effects of fire, nitrogen addition, and grazing or mowing on plant species diversity. In one experiment, richness declined on burned and fertilized treatments, whereas mowing maintained diversity under these conditions. In the second experiment, loss of species diversity due to frequent burning was reversed by bison, a keystone herbivore in North American grasslands. Thus, mowing or the reestablishment of grazing in anthropogenically stressed grasslands enhanced biodiversity

The continuing global decline of large carnivores has catalyzed great interest in reintroduction to restore populations and to reestablish ecologically functional relationships. I used variation in the distribution of four Holarctic prey species and their behavior as proxies to investigate the pace and intensity by which responses are lost or reinvigorated by carnivore repatriation. By simulating the presence of wolves (Canis lupus), tigers (Panthera tigris), and brown bears (Ursus arctos) at 19 transcontinental sites, I assayed three metrics of prey performance in areas with no large terrestrial carnivores (the polar islands of Greenland and Svalbard), extant native carnivores (Eastern Siberian Shield, boreal Canada, and Alaska); and repatriated carnivores (the Yellowstone region and Rocky Mountains). The loss and reestablishment of large carnivores changed the ecological effectiveness of systems by (1) dampening immediate group benefits, diminishing awareness, and diminishing flight reaction in caribou (Rangifer tarandus) where predation was eliminated and (2) reinstituting sensitivity to carnivores by elk (Cervus elaphus) and moose (Alces alces) in the Yellowstone region to levels observed in Asian elk when sympatric with Siberian tigers and wolves or in Alaskan moose sympatric with wolves. Behavioral compensation to reintroduced carnivores occurred within a single generation, but only the vigilance reaction of bison (Bison bison) in Yellowstone exceeded that of their wolf-exposed conspecifics from boreal Canada. Beyond these overt responses by prey, snow depth and distance to suitably vegetated habitat was related to heightened vigilance in moose and elk, respectively, but only at sites with carnivores. These findings are insufficient to determine whether similar patterns might apply to other species or in areas with alien predators, and they suggest that the presumed excessive vulnerability of naïve prey to repatriated carnivores may be ill-founded. Although behavior offers a proxy to evaluate ecological effectiveness, a continuing challenge will be to understand how naïve prey respond to novel or introduced predators.

The nature of domestic cattle origins in Africa are unclear as archaeological data are relatively sparse. The earliest domesticates were humpless, or Bos taurus, in morphology and may have shared a common origin with the ancestors of European cattle in the Near East. Alternatively, local strains of the wild ox, the aurochs, may have been adopted by peoples in either continent either before or after cultural influence from the Levant. This study examines mitochondrial DNA displacement loop sequence variation in 90 extant bovines drawn from Africa, Europe, and India. Phylogeny estimation and analysis of molecular variance verify that sequences cluster significantly into continental groups. The Indian Bos indicus samples are most markedly distinct from the others, which is indicative of a B. taurus nature for both European and African ancestors. When a calibration of sequence divergence is performed using comparisons with bison sequences and an estimate of 1 Myr since the Bison/Bos Leptobos common ancestor, estimates of 117-275,000 B.P. and 22-26,000 B.P. are obtained for the separation between Indians and others and between African and European ancestors, respectively. As cattle domestication is thought to have occurred approximately 10,000 B.P., these estimates suggest the domestication of genetically discrete aurochsen strains as the origins of each continental population. Additionally, patterns of variation that are indicative of population expansions (probably associated with the domestication process) are discernible in Africa and Europe. Notably, the genetic signatures of these expansions are clearly younger than the corresponding signature of African/European divergence.

The role that pathogens play in structuring ecological communities needs to be examined from both a theoretical and empirical perspective. This paper provides a brief introduction to the ecology and epidemiology of brucellosis in Yellowstone National Park. Observed patterns of infection for brucellosis in bison in national parks in the United States suggest that Brucella has a relatively sharply defined threshold for establishment and that the proportion of the host population infected increases as a relatively simple function of population density. Unfortunately, the threshold population for Brucella establishment in bison is low, a herd of at least 200 individuals; this makes it very hard to eradicate Brucella from wild populations. Simple calculations based on observed prevalence and recruitment data for the Yellowstone bison herd suggest that unacceptably high levels of culling would be required to eradicate brucellosis in the park. A simple mathematical model is used to describe aspects of the population dynamics of Brucella. The analyses suggest that an understanding of infectious disease dynamics is crucial to the management and conservation of wild and domestic ungulate species in and around national parks and other nature reserves. The consequences of disease control for the maintenance of biodiversity in other natural and captive communities need to be better understood.

The objectives of this study were to assess the adaptive significance of various reproductive strategies in American bison bulls and cows. The study was conducted with a herd of 260 to 360 animals at the Fort Niobrara National Wildlife Refuge near Valentine, Nebraska, USA. Dominance (or fighting ability) was not correlated with age for 7- to 13-yr-old bulls or with body mass for animals > 750 kg. Reproductive success among 6 + yr-old bulls ranged from 0 to 16 young sired per bull in 3 yr and was positively correlated with dominance rank. Dominant bulls bred during the first 2-3 weeks of rut and lower ranking bulls conserved energy and achieved a significant number of matings during the late rut. Challenging bulls engaged tending bulls in bellowing contests, probably to assess their stamina and elicit the attention of cows. Tending bulls bellowed defensively and bellowed at the same time and attempted to \"outbellow\" challengers. Cows apparently assessed variance in male \"quality\" and approached high-ranking bulls and ran away from low-ranking bulls. Bulls did not discriminate between cows based on their age or prior breeding performance, but tended and mated with any cows that were in estrus. Cows exhibited flehmen behavior toward each other, probably to stimulate the onset of estrus and synchronize time of copulation. All cows were equally likely to have a son or a daughter and did not exhibit a facultative adjustment in sex ratio based on prior breeding performance. The results are discussed relative to other studies on bison and other ungulates.

Brucellosis, a bacterial disease, was first noted in the Greater Yellowstone Area in 1917 and has been a chronic presence there since then. This book reviews existing scientific knowledge regarding brucellosis transmission among wildlife, particularly bison, elk, and cattle, in the Greater Yellowstone Area. It examines the mechanisms of transmission, risk of infection, and vaccination strategies. The book also assesses the actual infection rate among bison and elk and describes what is known about the prevalence of Brucella abortus among other wildlife.

The purpose of this study was to examine the effect of abundant native large herbivores on ecosystem function of a spatially and temporally heterogeneous temperate grassland. Net aboveground primary production (ANPP), large herbivore consumption (C), and dung deposit (D), an index of nutrient flow from herbivores to the soil, were measured in grassland ad shrub-grassland habitat on winter, transitional, and summer range used by herbs of elk (Cervus elaphus) and bison (Bison bison) in northern Yellowstone National Park. Temporary exclosures (5-7 per site) were moved ever 4 wk during the snow-free season to determine ANPP and C. Data were collected during 1988, a year of drought and unusually high elk and bison population levels, and 1989, a climatically near-average year, with dramatically fewer elk and bison. All three processes, ANPP, C, and D, varied widely among sites: ANPP range: 16-589 g/m^2, C range: 0-306 g/m^2, and D ranged: 0-68 g.m^2. An average of 45% of ANPP was consumed by herbivores. Production and consumption, and consumption and dung deposition were positively correlated across all sites. In addition, sites were grazed when plants were growing. There was a 19% reduction in ANPP from 1988 to 1989, likely caused by death or injury to plants during the 1988 drought. Drought also appeared to be partially responsible for reductions in elk and bison from 1988 to 1989, which were coincident with declines in C and D. Results indicate direct effects and suggest indirect effects of a single-season drought on grassland function that will persist for several years after the event.

The objective of this study was to analyze the incidence of bovine tuberculosis in animal species other than cattle in Central Europe from 1990 to 1999 and to assess the hazard of transmission of Mycobacterium bovis within and between the populations of domestic and wild animal species. The study was undertaken in Croatia, Czech Republic, Hungary, Poland, Slovakia and Slovenia. Mycobacterium bovis infection was diagnosed in 70 animals belonging to 17 species other than cattle. The set of wild animals comprised 12 European bison (Bison bonasus), 1 red deer (Cervus elaphus), 5 wild boars (Sus scrofa), and 1 European wild goat (Capra aegagrus) bred in a game park; 2 red deer and 1 bactrian camel (Camelus ferus) owned by a circus; 3 bisons (Bison bison), 4 tapirs (Tapirus terrestris), 1 cassowary (Casuarius casuarius), 8 sitatungas (Tragelaphus spekei), 3 elands (Taurotragus oryx), 1 gnu (Connochaetes taurinus), 8 reticulated giraffes (Giraffa cameloparadlis reticulata), 1 puma (Puma concolor), and 1 Vietnamese pot-bellied pig (Sus bucculentus) kept in zoological gardens. The infection was also demonstrated in 12 domestic pigs, 2 domestic sheep, and 4 dogs living on farms where bovine tuberculosis was diagnosed in cattle. Absolute numbers of the infected individuals are rather low, wild animals should be regarded as possible reservoirs of the causative agent of bovine tuberculosis.