Author : Courtney J. Duchardt
Publisher :
ISBN 13 : 9781658420501
Total Pages : 202 pages
Book Rating : 4.4/5 (25 download)
Book Synopsis Effects of Disturbance on Avian Diversity at a Grassland-sagebrush Ecotone by : Courtney J. Duchardt
Download or read book Effects of Disturbance on Avian Diversity at a Grassland-sagebrush Ecotone written by Courtney J. Duchardt and published by . This book was released on 2019 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combating biodiversity loss caused by human land use is one of the greatest challenges facing conservation biologists and ecologists worldwide. As postulated by the habitat-heterogeneity hypothesis, biodiversity is often greatest in areas with high habitat heterogeneity, such as areas along transitional zones (i.e., ecotones) between biomes. As such, these ecotones are a natural focus of biodiversity conservation efforts, but the complexity of these landscapes may be especially challenging for management. This issue is especially salient at the ecotone between the Great Plains and sagebrush (Artemisia spp.) steppe, where ecosystem services including livestock grazing and energy extraction are often at odds with the needs of extremely diverse wildlife, including imperiled guilds of grassland and sagebrush birds. These two guilds have very different habitat requirements and responses to disturbance, but both are major conservation targets both in Wyoming and across their ranges. The intent of my dissertation was to provide a better understanding of the habitat requirements and disturbance tolerances of both grassland and sagebrush birds within the ecotonal landscape of the U. S. Forest Service–Thunder Basin National Grassland of northeastern Wyoming. The proximate application of this research is to inform both managers and citizens in the region of habitat requirements and tolerances of avian species, with a goal of managing the landscape for long-term sustainability of all target populations. My dissertation is presented in four journal-formatted chapters. The main objective of Chapter Two was to evaluate the responses of a suite of grassland and sagebrush birds to different aspects of two forms of natural disturbance common within this landscape: fire and black-tailed prairie dog (Cynomys ludovicianus) burrowing and herbivory. We found that while sagebrush bird species were equally intolerant to both disturbance types due to loss of sagebrush, the mountain plover (Charadrius montanus) relied almost solely on prairie dog disturbance in this landscape. This chapter was published in Ecosphere in fall 2018 with coauthors L. Porensky, D. Augustine, and J. Beck (Duchardt, C. J., L. M. Porensky, D. J. Augustine, and J. L. Beck. 2018. Disturbance shapes avian communities on a grassland–sagebrush ecotone. Ecosphere 9(10):e02483). Chapter 3 examined landscape-scale responses of shortgrass, midgrass, and sagebrush birds to different aspects of black-tailed prairie dog disturbance. While sagebrush birds were most sensitive to the presence of long-term colony occupation, mid-grass species were more sensitive to distance to colony edge, reaching lowest abundances at colony cores. Most interesting, mountain plovers, which were found exclusively on prairie dog colonies, peaked in abundance within 500–800 m from a colony edge, declining nearer to colony cores. This is the first evidence that mountain plovers may not benefit from a “bigger is better” approach to prairie dog management. This chapter was published in Landscape Ecology in spring 2019 with coauthors D. Augustine and J. Beck (Duchardt, C. J., D. J. Augustine, and J. L. Beck. Threshold responses of grassland and sagebrush birds to patterns of disturbance created by an ecosystem engineer. Landscape Ecology 34:895–909). Chapter 4 provided a more in-depth analysis on the breeding ecology of one of the most imperiled species in the system, the mountain plover. We combined point count data with nest site-selection and survival data to better understand plover responses to different aspects of prairie dog disturbance and other features of this system. Supporting the findings of Chapter 3, plover abundance peaked in mid-sized (100–600 ha) prairie dog colonies, with lower abundances in small (100) and very large (600–4000 ha) colonies, although abundance was also highest in areas occupied by prairie dogs 6 years with ample bare ground. Both adult density and nest-site selection were influenced somewhat more by maximum vegetation height than visual obstruction. As with other precocial species, nest survival probability increased with nest age, but was also influenced by weather. This chapter was accepted by The Condor: Ornithological Applications in fall 2019 with coauthors J. Beck and D. Augustine, with revisions submitted September 2019. Chapter 5 provides an in-depth analysis on the effects of both natural and anthropogenic disturbance on sagebrush birds. We examined the effects of vegetation, prairie dog disturbance and anthropogenic disturbance (road density, oil wells, and mining) on two sagebrush passerines (Brewer’s sparrow [Spizella breweri] and sage thrasher [Oreoscoptes montanus]) as well as greater sage-grouse (Centrocercus urophasianus) lek attendance. Although aspects of prairie dog disturbance did have negative impacts on sagebrush birds, these models were much less competitive than aspects of anthropogenic disturbance or sagebrush cover alone. Within this system, concerns about burgeoning energy development are likely more pressing than potential conflicts between sagebrush avifauna and black-tailed prairie dogs. This chapter has been formatted for submission in The Journal of Wildlife Management with coauthors J. Beck and D. Augustine.
