Grasslands are inherently dynamic in space and time, evolving with frequent disturbance from fire and herbivores. As a consequence of human actions, many remaining grasslands have become homogenous, which has led to reduced ecosystem function, biodiversity loss, and decreased ecological services. Previous research has shown that restoring inherent heterogeneity to grasslands can increase avian diversity, but the amount of heterogeneity (i.e., number of patches or fire return interval) and the impact on avian community stability have yet to be investigated. We used a unique landscape-level design to examine avian response to interacting fire and grazing across multiple experimental landscapes that represented a gradient of fire- and grazing-dependent heterogeneity. We used seven landscapes (430-980 ha; x = 627 ha) with varying levels of patchiness ranging from annually burned (one single patch) with spring-only fires to a four-year fire return interval with spring and summer fires (eight patches). This design created a range of heterogeneity as a result of pyric herbivory, an ecological process in which fire and grazing are allowed to interact in space and time. We found that greater heterogeneity across experimental landscapes resulted in increased avian diversity and stability over time. An index of bird community change, quantified as the sum of the range of detrended correspondence analysis axis site scores, was nearly four times greater in the most homogenous experimental landscape when compared to the most heterogeneous experimental landscape. Species responses were consistently positively associated with increased heterogeneity at the landscape scale, and within-experimental-landscape responses were most often related to litter cover, litter accumulation, and vegetation height. We conclude that increased fire- and grazig-dependent heterogeneity can result in high variability in the bird community at finer, transect scales, but increased diversity and stability at broad landscape scales. We recommend that future management efforts in rangelands focus on restored disturbance processes to increase heterogeneity and improve grassland bird conservation.

Abstract. The impacts of climate driven change on ecosystem processes and biodiversity are pervasive and still not fully understood. Biodiversity loss, range shifts, and phenological mismatches are all issues associated with a changing climate that are having significant impacts on individuals and ecosystems alike. Investigating and identifying effective management strategies that can conserve vulnerable species should be the focus of current and future climate change research. We investigated thermal properties of habitat for an imperiled grouse (Greater Prairie-chicken; Tympanuchus cupido) in tallgrass prairie characterized by heterogeneous fire and grazing (the fire-grazing interaction). We examined operative temperature at varying scales relevant to grouse and used historic and forecasted climate data to estimate thermal stress during nesting activities. We found that heterogeneous grasslands have high thermal variability with operative temperature ranging as much as 238C across the landscape. Grouse exhibited strong selection for cooler thermal environments as nest sites were as much as 88C cooler than the surrounding landscape, and fine-scale differences in thermal environments were nearly 48C cooler than sites within 2 m of nests. Additionally, forecasted climate scenarios indicate grouse will experience 2-4 times the number of hours above thermal stress thresholds, emphasizing the need for informed conservation management. Overall, these data provide evidence that variation in grassland structure resulting from the fire-grazing interaction may be important in moderating thermal environments and highlights the complex and interactive effects of restored ecological processes on ecosystems.

Summary1. Anthropogenic structures such as those associated with energy development are a major threat to wildlife as a result of direct and indirect effects on populations. Species already imperilled as a result of habitat loss and alteration also may be the most threatened by rapidly increasing energy development, and these added pressures could lead to species extinctions and further declines in biodiversity. 2. Of particular concern are tetraonids (grouse spp.) which have life cycles that require large, intact habitats to persist. We searched the peer-reviewed literature to assess impacts of six anthropogenic structures (i.e. oil and gas, fences, wind turbines, buildings, roads and power lines) on grouse survival and displacement behaviour across four different time periods in a grouse life cycle (i.e. year around, lekking, nesting and brooding). 3. We used 5 studies that examined a total of 23 study-structure combinations to assess displacement behaviour in grouse and found an average effect of À1Á40 (95% CI: À1Á50, À1Á31), indicating that anthropogenic structures displace grouse. Similarly, we used 9 studies examining a total of 17 study-structure combinations to assess survival and found an average effect of À1Á11 (95% CI: À1Á33, À0Á88), indicating a negative effect of structures on grouse survival. 4. Oil and gas structures had the greatest negative effect on displacement behaviour (E = À2Á41, 95% CI: À3Á28, À1Á54), and of the periods of the life cycle examined, lek attendance was most affected (E = À4Á85, 95% CI: À6Á39, À3Á31). 5. Synthesis and applications. This data-driven synthesis reveals an overall negative effect of anthropogenic structures on grouse displacement behaviour and survival. Specifically, grouse were displaced and had lower survival in the presence of oil and gas structures and the presence of roads resulted in displacement behaviour. Too few studies existed to examine the specific effects of wind turbines and fences on displacement behaviour and the impact of wind turbines, fences, buildings and power lines on survival, which emphasizes the need for research assessing the influence of these structures on wildlife. Future management should focus on limiting the amount of oil and gas and road development in areas occupied by extant grouse populations, and if unavoidable, new infrastructure should be placed at low densities away from known lekking locations as leks appear sensitive to disturbance from anthropogenic structures.

Abstract. Grassland birds have experienced greater population declines than any other guild of birds inNorth America, and yet we know little about habitat use and the affects of management during their nonbreeding period on wintering grounds. The paucity of information on wintering grassland birds limits our ability to develop effective conservation strategies. We investigated habitat use by the winter bird community in grasslands with restored heterogeneity resulting from the interactive effects of fire and grazing. We used 500 m line transects distributed across patches (i.e., ,13, 13-24, and .24 months post disturbance) resulting from spring burning with growing season grazing (April-Sept) and quantified avian relative abundance, community structure, and probability of patch occupancy while accounting for imperfect detection. Grassland structure that resulted from the fire-grazing interaction created heterogeneity among patches that influenced avian habitat use during winter. Generalist birds such as the Savannah Sparrow (Passerculus sandwichensis) and meadowlarks (Sturnella spp.) were relatively common in all patch types while more specialized species such as the Smith's Longspur (Calcarius pictus) and Le Conte's Sparrow (Ammodramus leconteii ) reached greatest abundance and probability of occupancy in the patches with the least and greatest time post disturbance, respectively. This research provides novel information on the response of wintering birds to restored ecological processes in grasslands and can improve efforts to create effective conservation strategies. Our findings add to a growing body of literature supporting the use of fire and grazing to create a shifting grassland mosaic that increases vegetation structural and compositional heterogeneity and maximizes native biodiversity within rangeland ecosystems through the conservation of natural patterns and processes.

In many grasslands, grazing by large native or introduced ungulates drives ecosystem structure and function. The behavior of these animals is important as it directs the spatial effects of grazing. To the degree that temperature drives spatial components of foraging, understanding how changes in climate alter grazing behavior will provide guidance for the conservation of ecosystem goods and services. We determined the behavioral response of native bison (Bison bison) and introduced cattle (Bos taurus) to temperature in tallgrass prairie within the Great Plains, USA. We described the thermal environment by measuring operative temperature (the temperature perceived by animals) through space and time. Site selection preferences of ungulates were quantified using resource selection functions. Woody vegetation in tallgrass prairie provided a cooler thermal environment for large ungulates, decreasing operative temperature up to 16 °C in the heat of the summer. Cattle began to seek thermal refugia at lower air temperatures (24 °C) by selecting areas closer to woody vegetation and water sources. Bison, however, sought refugia within wooded areas at higher air temperatures (36 °C), which occurred much less frequently. Both species became more attracted to riparian areas as air temperature increased, with preferences increasing tenfold during the hottest periods. As predicted warming occurs across the Great Plains and other grasslands, grazing behavior and subsequent grazing effects will be altered. Riparian areas, particularly those with both water and woody vegetation, will receive greater utilization and selection by large ungulates. The use of native grazers for conservation or livestock production may mitigate negative effects caused by increased temperatures.