John Derek Scasta

Pyric-Herbivory to Manage Horn Flies (Diptera: Muscidae) on Cattle

Abstract. Pyric-herbivory, defined as fire-driven grazing, was applied as patch-burn grazing management and compared to traditional management (grazing without fire) for the potential to mitigate horn flies, Haematobia irritans (L.), on cattle in Iowa and Oklahoma. Stocking rate was conservative at both locations, and all cattle were black angus, Bos taurus (L.). Study design was two treatments replicated three times for a total of six pastures at each location. Average pasture sizes were 27 ha in Iowa and 55 ha in Oklahoma. The primary objective was to assess response of the Eurasian origin horn fly to fire and grazing disturbances. Numbers of horn flies were assessed at both locations and analyzed for location, treatment, and interaction (location × treatment). Numbers of horn flies differed only between treatments. Patch-burn grazing management resulted in 41% reduction of horn flies, less than in the traditional management system regardless of location (P < 0.0001). Cattle in pastures managed with patch-burn grazing were near the universally accepted economic threshold for treatment (200 flies per cow) compared to double the economic threshold on cattle under traditional management. Cattle in pastures managed with patch-burn grazing were below the behavioral threshold of 300 flies per cow and were expected to have increased grazing time associated with a reduction in stress annoyance behaviors. These results demonstrated that grazing management that includes fire can reduce horn flies on cattle in rangeland systems.

Fire and Parasites: An Under-Recognized Form of Anthropogenic Land Use Change and Mechanism of Disease Exposure

Anthropogenic land use changes have altered ecosystems and exacerbated the spread of infectious diseases. Recent reviews, however, have revealed that fire suppression in fire-prone natural areas has not been recognized as a form of anthropogenic land use change. Furthermore, fire suppression has been an under-recognized mechanism altering the risk and transmission of infectious disease pathogens and host–parasite dynamics. However, as settlement patterns changed, especially due to colonial expansion in North America, Africa, and Australia, fire suppression became a major form of land use change which has led to broad-scale ecosystem changes. Because parasites of humans and animals can vector viral, bacterial, prion, fungal, or protozoan pathogens, concomitant changes associated with anthropogenic-induced changes to fire frequencies and intensities are of concern. I provide reference to 24 studies that indicate that restoring fire in natural areas has the potential to reduce ectoparasites without wings such as ticks, chiggers, fleas, and lice; ectoparasites with wings such as mosquitos, horn flies, face flies, and stable flies; and endoparasites affecting livestock and wildlife. This suggests that fire ecology and parasitology be considered as a priority area for future research that has implications for both humans and animals.

Patch-burn grazing (PBG) as a livestock management alternative for fire-prone ecosystems of North America

Many rangelands of the world are fire dependent and display a strong interaction between fire and grazing on animal behavior, productivity and ecosystem processes. The application of this fire–grazing interaction as patch-burn grazing (PBG) has recently been promoted in North America to conserve biodiversity and as an alternative for livestock management in fire-prone ecosystems to enhance forage quality and other production benefits. PBG is functionally applied by burning spatially and temporally discrete patches to allow livestock to choose where and when to graze. However, considering that the primary intent of PBG in fire-dependent ecosystems has been for the conservation of biodiversity, we synthesized the peer-reviewed literature to assess PBG as an alternative strategy for livestock management in fire-prone ecosystems. We reviewed the literature to assess PBG as an alternative livestock management approach to optimize animal production and conserve biodiversity in fire-prone ecosystems. We reviewed the results of 83 studies that focused on two main areas: (1) livestock production and inputs and (2) maintaining or improving ecosystem functioning and biodiversity to support sustainable livestock production. PBG can optimize cattle production by offsetting input costs such as supplemental feed, insecticides, herbicides, mechanical brush control, veterinary costs and cross-fencing. PBG can also maintain native herbaceous plant communities that are the resource base for cattle grazing enterprises by reducing woody plant encroachment, stimulating above- and below-ground biomass of native perennial grasses, enhancing nutrient cycling and optimizing plant diversity. PBG creates a habitat mosaic critical for many trophic levels of wildlife, particularly grassland birds, which are currently in decline. Further research is needed to clarify the potential environmental gradients defining applicability of PBG, economic outcomes of PBG, potential gastro-intestinal parasite control with PBG and other metrics of animal production. Overall, PBG is a viable management approach to improve productivity and biodiversity in fire-regulated grassland ecosystems in a manner supported by both fire and grazing disturbances. This is especially true when these communities have other organisms that depend on periodic disturbance and interaction with large animal grazing and is supported by ample empirical research.

Meta-Analysis of Exotic Forages as Invasive Plants in Complex Multi-Functioning Landscapes

Introducing exotic forages in the attempt to enhance livestock and wildlife forage has been practiced widely for over a century. These forage species are selected for traits conferring persistence under stress, potentially yielding invaders that transform native plant communities. Using standardized systematic review guidelines and meta-analytical techniques we quantified effects of exotic forage invasion on change of native plant community structure, and compared the magnitude and direction of change across exotic forage species, plant functional groups, and structure of plant communities. Our study of 13 exotic forage species in North America (six C4 grasses, three C3 grasses, and four legumes) yielded 35 papers with quantitative data from 64 case studies. Nine of the 13 species met our inclusion criteria for meta-analysis. The overall effect of exotic forage invasion on native plant communities was negative ( =  −0.74; 95% confidence interval [CI]: −0.29 to −0.25). The effect size was most negative for two C4 grasses, Lehmann lovegrass and Old World bluestems. A negative effect was also expressed by C3 and C4 grass functional groups, and these effects were stronger than for legumes. Effect size differed among measures of plant community structure, with the greatest negative effect on native plant biomass and the least negative effect on species evenness. Weighted fail-safe numbers indicated publication bias was not an issue. Exotic forage species are important for agricultural production but may threaten complex multi-functioning landscapes and should be considered as a subset of potentially invasive exotic species. Characteristics making exotic forages different from other exotic plants hinge on pathways of selection and dispersion: selection is based on persistence mechanisms similar to characteristics of invasive plants; dispersion by humans is intentional across expansive geographic regions. Exotic forages present a complex socio-ecological problem exacerbated by disconnected scientific disciplines, competing interests between policy and science, and organized efforts to increase food production. Nomenclature: Lehmann lovegrass, Eragrostis lehmanniana (Nees); Old World bluestems, (plains) Bothriochloa ischaemum var. ischaemum (L.) Keng. and (yellow) Bothriochloa ischaemum var. songarica (Rupr. ex Fisch. & C.A. Mey.) Celarier & Harlan. Management Implications: The breeding, selection, and introduction of exotic forages have led to changes in native terrestrial plant communities in North America. Although not all exotic forages have become invasive, many have become problematic and shown aggressive expansion into areas beyond the initial plantings. Potential changes to the native plant community include reduced species richness, evenness, and diversity, and lower total cover and biomass. These exotic forage species are successful invaders because they are selected for traits conferring persistence under stress such as grazing, repeated haying, and environmental stress. Many of the desirable traits selected for in forage species are similar to traits common in invasive plants such as ease of establishment, high seed production with extensive longevity, vigorous vegetative reproduction, rapid growth rate, competitive resource use, and resistance to removal and predators (insects and disease). Managers should carefully consider invasion potential to guide species selection when exotic forage is proposed in a hay or permanent pasture scenario. Managers may also consider using native seed mixes, especially for restoration of natural areas, but native seed costs are currently prohibitive and exotic seed is typically cheaper. This cost discrepancy continues to constrain reseeding natural areas or planting of Conservation Reserve Program fields with seed mixes to optimize wildlife use. We also suggest that managers monitor areas of exotic forage presence and begin measuring expansion over time into other areas. Our results also suggest that managers consider limiting the establishment of wildlife food plots with exotic forage species that may invade beyond the planted areas. Finally, dialogue between managers and other stakeholders is needed to discuss innovative solutions for exotic forage invasion situations or potential situations.

Drought Mitigation for Grazing Operations: Matching the Animal to the Environment

On the Ground With expected increases in drought frequency and severity, long-term drought management strategies that focus on cattle selection and natural resource management are essential. The livestock industry in general unintentionally tends to select for cattle that do not perform to their maximum potential in limited-resource environments. We discuss the implications of cattle selection based on characteristics such as genetic potential, cow size, and hide color. In a hypotheticalmodel, we found that because forage requirements for smaller cows are lower than forage requirements for larger cows, using a herd of smaller cows produces a larger total calf crop if cow size and milk do not lead to greater calf production. Because grazed forage remains the least expensive source of nutrients tomaintain the cow herd,matching cow size and milk production potential to forage resources to optimize forage utilization and reproductive efficiency should be considered a rangeland drought mitigation strategy. Contemporary strategies such as using EPDs and selection indexes to manage maternal traits such as mature weight and maintenance energy requirements can be integratedwith conventional drought mitigation strategies that focus on resource qualitymanagement.

Droughts and Wildfires in Western U.S. Rangelands

On the Ground Because fire activity fluctuates with short- and long-term term weather and climate trends, understanding trends relative to climate forecasts is critical to mitigating the loss of life and property and rapid vegetation state changes. Through the analysis of charcoal and trees scars, historical droughts and fire patterns can be quantified retrospectively for hundreds of years. This evidence suggests that generally fire was most frequent during warm-dry periods as opposed to cool-moist periods. However, arid regions may see an increase of fire activity with an increase of moisture due to inherent fuel load limitations. Using federal wildfire and weather data from 2002 to 2015 for New Mexico, Nevada, Oklahoma, and Wyoming, we demonstrate that the worst wildfire activity occurred after average or above average precipitation years followed by drought in Oklahoma and Wyoming. Nevada wildfire activity was correlated with precipitation the preceding year, and NewMexico wildfire activity was not correlated with annual precipitation or preceding year precipitation. The effects of future drought on fire intensity and severity are projected to be highly variable because they are both a function of fuel load. However, the potential for very large wildfires is predicted to increase; fire weather is expected to create hotter and drier conditions that start earlier and last longer; and the relative changes may be most noticeable in cooler regions that are of higher latitude and elevation.

Drought Consequences for Cow-Calf Production in Wyoming: 2011—2014

On the Ground Drought reduces forage quantity and carrying capacity, but reductions in cow-calf performance measured by calf average daily gain (ADG) and weaning weight (WW) are less understood. From 2011 to 2014, a period with very dry and very wet years, we assessed an adjusted 210 day WW and ADG for a total of 869 calves on two University of Wyoming ranches. We found WW was up to 99 pounds (lb) lower, and ADG was up to 0.47 lb lower between the driest and wettest years. For each one inch reduction in precipitation, WW are predicted to be 7 lb to 14 lb lower, ADG is expected to be 0.03 lb to 0.07 lb lower, and dollar per head values

Rancher-reported efficacy of lethal and non-lethal livestock predation mitigation strategies for a suite of carnivores

12 to

Climate Extremes, Vegetation Change, and Decoupling of Interactive Fire-Grazing Processes Exacerbate Fly Parasitism of Cattle

27 lower, depending on calf sex and ranch location. If drought occurs, or continues to escalate in frequency and severity, WW reductions, ADG reductions, and value per head reductions should be expected and documented for strategic planning and/or compensation programs.

Author Correction: Rancher-reported efficacy of lethal and non-lethal livestock predation mitigation strategies for a suite of carnivores

Pastoralists have dealt with livestock losses from predators for millennia, yet effective mitigation strategies that balance wildlife conservation and sustainable agriculture are still needed today. In Wyoming, USA, 274 ranchers responded to a retrospective survey, and rated the efficacy of predation mitigation strategies for foxes, dogs, coyotes, wolves, bobcats, mountain lions, bears, and birds (buzzards, eagles, hawks, ravens). Rancher reported efficacy of mitigation varied by predator species, mitigation strategy, and lethality of strategies, but not livestock type. Ranchers perceive they were most effective at mitigating predation by foxes and coyotes, moderately effective at mitigating large carnivores, and the least effective at mitigating birds. Ranchers also reported that avian predators seem to be the most challenging predator type. The general perception was lethal mitigation strategies were more effective than non-lethal strategies, with guard animals showing the most potential among the non-lethal options. In general, ranchers did not perceive non-lethal strategies as a proxy for lethal strategies. However, a few ranchers reported being successful with non-lethal options such as herding, fencing, and stalling at night but more details about such successful applications are needed. Innovation in current or novel non-lethal mitigation strategies, and examples of efficacy, are needed to justify producer adoption.